Magnetic resonance imaging of the prostate: interpretation using the PI-RADS V2. / Resonancia magnética de próstata: lectura con el sistema PI-RADS V2.

OBJECTIVE: Version 2 of the Prostate Imaging and Reporting and Data System (PI-RADS) was developed to help in the detection, location, and characterization of prostate cancer with magnetic resonance imaging (MRI). Its recommendations for standardizing image acquisition parameters aims to reduce variability in the interpretation of MRI studies of the prostate; this approach, together with structured reporting, has the added value of improving communication among radiologists and between radiologists and urologists. This article aims to explain the PI-RADS v2 classification in a simple way, using illustrative images for each of the categories, as well as to recommend the use of a standard technique that helps ensure the reproducibility of multiparametric MRI. CONCLUSION: The PI-RADS v2 is simple to appy when reading multiparametric MRI studies of the prostate. It is important for radiologists doing prostate imaging to use the PI-RADS v2 in daily practice to write clear and concise reports that improve communication between radiologists and urologists.

Effect of diabetes on nitric oxide metabolism during cardiac surgery.

The metabolism of nitric oxide (NO) during cardiac surgery is unclear. We studied the effect of diabetes on NO metabolism during cardiac surgery in 40 subjects (20 with diabetes and 20 without diabetes). The patients were randomized to receive an infusion of physiological saline or nitroglycerin (GTN) at 1 microg. kg(-1). min(-1) starting 10 min before the initiation of cardiopulmonary bypass and then continuing for a period of 4 h. Blood and urine samples were collected at several time points for up to 8 h. NO metabolites were determined by the measurement of nitrate/nitrite (NOx, micromol/mmol creatinine) and cyclic guanosine monophosphate (cGMP, nmol/mmol creatinine) in plasma and urine. Plasma insulin levels were also determined at selected time points. Plasma NOx levels before surgery were significantly elevated in the group with diabetes compared with the group without diabetes (P < 0.001), and values were further increased during surgery in the former (P = 0.005) but not in the latter (P = 0.8). The greater plasma NOx values in patients with diabetes were matched by commensurate elevations in plasma cGMP levels (P = 0.01). Interestingly, infusion of GTN, an NO donor, significantly reduced plasma NOx (P < 0.001) and its urine elimination (P < 0.001) in patients with diabetes without reducing plasma cGMP levels (P = 0.89). Cardiac surgery increased plasma insulin in patients with and without diabetes; this increase was delayed by the infusion of GTN, but it was not related to the changes in NO production. In conclusion, NO production during cardiac surgery is increased in patients with diabetes, and this elevation can be blunted by the infusion of GTN in a rapid and reversible manner.

Diltiazem and progression of myocardial ischemic damage during coronary artery occlusion and reperfusion in porcine hearts.

This study was designed to investigate whether a cardioprotective intervention could delay the completion of necrosis so that subsequent reperfusion would be more useful. Thirty-six pigs were randomly allocated to treatment with diltiazem (15 micrograms/kg per min) or saline solution and to a 60 or 120 minute coronary occlusion period followed by reperfusion. The treatment was begun 15 minutes before coronary occlusion and terminated 75 minutes after reperfusion. Twenty-four hours after the procedure, the heart was sliced and incubated in triphenyltetrazolium chloride. The infarct area and the maximal transmural area of extension of the infarct were calculated by planimetry. The total number of red blood cells in a transmural section was also counted. In the pigs with a 60 minute coronary occlusion, diltiazem (compared with saline solution) significantly reduced infarct size from 9.7 +/- 1.5% of left ventricular mass to 5.9 +/- 0.6% (p less than 0.05) and the percent transmural extension from 0.72 +/- 0.05 to 0.61 +/- 0.05% (p less than 0.05). Red blood cell extravasation in the infarcted area was reduced from 161,934 +/- 59,905 to 78,525 +/- 46,484 cells/mm3 (p less than 0.05) with diltiazem and the percent transmural extension of the hemorrhagic necrosis from 70 +/- 10 to 36 +/- 15% (p less than 0.05). No such differences were observed in the 120 minute coronary occlusion groups. Mean red blood cell counts and the extent of hemorrhagic necrosis did not correlate with either infarct size or transmural extension.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of potassium channel modulation during global ischaemia in isolated rat heart with and without cardioplegia.

OBJECTIVE: The opening of potassium (K+) channels during regional ischaemia may, by inducing rapid contractile arrest, be an intrinsic energy sparing mechanism. Thus K+ channel openers (for example, lemakalim) exert significant anti-ischaemic effects, whereas glibenclamide exacerbates ischaemic contracture and limits postischaemic functional recovery. The aim of the study was to investigate the ability of these compounds to influence ischaemic injury when used either alone or in combination with rapid arrest induced by a high K+ cardioplegic solution. METHODS: Contractile function of isolated Langendorff perfused rat hearts was assessed using an intraventricular balloon. Hearts were subjected to normothermic global ischaemia (20 min) or cardioplegic arrest (35 min) with and without glibenclamide or lemakalim. Lemakalim (10 mumol.litre-1) or glibenclamide (10 mumol.litre-1) was given, in the presence or absence of cardioplegia, for 2 min immediately prior to the onset of ischaemia. The rate of ischaemia induced contractile failure, the severity of ischaemic contracture, and the degree of postischaemic functional recovery were all measured. RESULTS: In the absence of cardioplegia, the time to contractile arrest in control hearts was 133 (SEM 4) s. This was increased by glibenclamide, to 145(6) s, and decreased by lemakalim, to 112(6) s. The time to onset of ischaemic contracture [8(1) min] was accelerated by glibenclamide [4(1) min] and delayed by lemakalim [14(1) min]. Lemakalim significantly improved the recovery of left ventricular developed pressure from 49(7)% in control hearts to 65(3)%, and left ventricular end diastolic pressure from 41(3) to 21(4) mm Hg. Hearts pretreated with glibenclamide showed similar recoveries to control hearts. During reperfusion, lemakalim exerted a transient vasodilator effect whereas glibenclamide caused a transient vasoconstriction. When either glibenclamide or lemakalim was added to a high K+ cardioplegic solution and hearts rendered ischaemic for 35 min, the ability of both compounds to influence ischaemic contracture and postischaemic functional recovery was lost. In additional studies the effect of lemakalim on the relative times to ischaemia induced mechanical failure and electrical arrest was assessed. In control hearts the time to contractile failure was 128(5) s and the time to electrical arrest was 241(30) s, while in the lemakalim treated hearts the values were 103(2) s and 509(161) s, respectively. In the lemakalim group all the hearts showed sustained ventricular arrhythmias; in the control group there were no arrhythmias. CONCLUSIONS: Lemakalim can exert a significant anti-ischaemic effect when given alone. This effect is lost when it is used in combination with high K+ cardioplegia. The anti-ischaemic properties of lemakalim may thus be limited to its ability to accelerate contractile arrest.

Preconditioning the human myocardium by simulated ischemia: studies on the early and delayed protection.

BACKGROUND: There are data supporting the existence of ischemic preconditioning in man. This study investigated the most effective preconditioning protocol for the human myocardium and whether the second window of ischemic preconditioning (24 h) is as protective as the first window (< or = 2 h). METHODS AND RESULTS: Right atrial appendages (n = 6/group) obtained during coronary bypass surgery were prepared and superfused with normoxic and normothermic Krebs-Henseleit solution. After 30 min stabilisation, muscles were subjected to various preconditioning protocols followed by 90 min ischemia and 120 min reperfusion. At the end of each protocol, the leakage of creatinine kinase (CK, U/g wet wt) and the reduction of MTT to insoluble formazan dye (OD/mg wet wt), an index of cell viability, were measured. In study 1, preconditioning was induced by 2, 3, 5 and 10 min of ischemia followed by 5 min reperfusion. In study 2, 1-4 cycles of 2 or 5 min ischemia-5 min reperfusion were applied. In study 3, preconditioning was induced by 5 min ischemia-5 min reperfusion followed by 1, 2, 3 or 4 h reperfusion before the subsequent 90 min ischemia. In study 4, preconditioning with 5 min ischemia followed by 5 min reperfusion either immediately preceded 30 or 90 min ischemia/120 min reperfusion or was applied 24 h before. In study 1 and 2, optimal protection was achieved with 5 min or two cycles of 2 min preconditioning ischemia (CK = 3.06 +/- 0.31 and 2.89 +/- 0.02; MTT = 0.56 +/- 0.05 and 0.47 +/- 0.09, respectively vs. CK = 5.56 +/- 0.52 and MTT = 0.18 +/- 0.04 in ischemia alone group; P < 0.05). In study 3, protection was observed 2 h after preconditioning (CK = 3.43 +/- 0.22 and MTT = 0.46 +/- 0.09; P < 0.01 vs. ischemia alone group) but it was lost beyond 2 h (CK = 6.30 +/- 0.56 and MTT = 0.16 +/- 0.02 after 3 h; P = NS vs. ischemia alone group). In study 4, protection was observed 24 h following preconditioning when the atrial specimens were exposed to 30 min ischemia (CK = 2.96 +/- 0.38 and MTT = 0.61 +/- 0.01 vs. CK = 4.56 +/- 0.26 and MTT = 0.43 +/- 0.02 in ischemia alone group, P < 0.05); however, when the period of ischemia was extended to 90 min the beneficial effect of preconditioning was lost (CK = 10.28 +/- 0.05 and MTT = 0.11 +/- 0.05 vs. CK = 9.56 +/- 0.62 and MTT = 0.104 +/- 0.05 in ischemia alone group, P = NS). CONCLUSIONS: In the isolated human myocardium maximal protection induced by preconditioning is achieved by a total 4-5 min ischemic stimulus, an effect that is lost beyond 2 h of its application. Two windows of protection were identified, the first (< or = 2 h) being more potent than the second (24 h).

Evidence for mitochondrial K ATP channels as effectors of human myocardial preconditioning.

BACKGROUND: Sublethal periods of ischemia preceding a prolonged interval of ischaemia protect the myocardium. This myocardial preconditioning (PC) appears to be effected by KATP channels. These channels occur both in the sarcolemma and the mitochondrial membrane. We investigated whether mitochondrial KATP channels are the end-effector of PC in the human myocardium. METHODS: Right atrium specimens obtained from patients undergoing cardiac surgery were prepared and incubated in buffer solution at 37 degrees C. After 30-min stabilisation, the muscles were made ischemic for 90 min and then reperfused for 120 min. The preparations were randomised into eight experimental groups (n = 6/group): (1) Aerobic control--incubated in oxygenated buffer for 210 min, (2) ischemia alone--90 min ischemia followed by 120 min reperfusion, (3) PC--preconditioned with 5 min ischemia/5 min reperfusion, (4) Glibenclamide (10 microM) in the incubation media for 10 min before PC, (5) 5-hydroxydecanoate (5-HD, MitoKATP blocker, 1 mM) in the incubation media for 10 min before PC, (6) HMR 1883 (SarcKATP blocker, 10 microM) in the incubation media for 10 min before PC, (7) Pinacidil (0.5 mM) in the incubation media for 10 min before ischemia, and (8) Diazoxide (MitoKATP opener, 0.1 mM) in the incubation media for 10 min before ischemia. Creatinine kinase leakage into the medium (CK, IU/g wet wt) and MTT reduction (OD/mg wet wt.), an index of cell viability, were assessed at the end of the experiment. RESULTS: Ischemia alone resulted in a significant increase in CK leakage (8.01 +/- 0.35) and decrease in MTT (0.15 +/- 0.01) from the values seen in the aerobic control (2.24 +/- 0.52 and 0.78 +/- 0.10 respectively, P < 0.05 in both instances). PC fully reversed the effect of ischemia (CK = 2.97 +/- 0.31 and MTT = 0.61 +/- 0.05; P < 0.05 vs. ischemia alone group but P = NS vs. aerobic control group). Both Glibenclamide and 5-HD abolished the protection induced by PC (CK = 6.23 +/- 0.5 and 7.84 +/- 0.64; MTT = 0.18 +/- 0.03 and 0.13 +/- 0.02, respectively, P < 0.05 vs. PC), but interestingly, the protective effect of PC was not abolished by HMR 1883 (CK = 2.85 +/- 0.24 and MTT = 0.58 +/- 0.05, P = NS vs. PC). Diazoxide mimicked the protective effect of PC (CK = 3.56 +/- 0.32 and MTT = 0.58 +/- 0.02, P = NS vs. PC), however pinacidil exhibited less protection than PC (CK = 4.02 +/- 0.16 and MTT = 0.30 +/- 0.02, P < 0.05 vs. PC). CONCLUSIONS: These studies demonstrate that KATP channels are the end-effectors of ischemic preconditioning and that protection is mediated by mitochondrial KATP channels in human right atrial myocardium.

Metabolic and functional effects of the nucleoside transport inhibitor R75231 in the ischaemic and blood reperfused rabbit heart.

OBJECTIVE: The ability of R75231, a nucleoside transport inhibitor, to influence adenine nucleotide metabolism and enhance postischaemic functional recovery was assessed in the blood perfused rabbit heart. METHODS: Hearts (n = 8 per group) from donor animals were excised and perfused with blood at 37 degrees C from a support rabbit. After 20 min of aerobic perfusion hearts were arrested with St Thomas' Hospital cardioplegic solution (2 min at 37 degrees C) and rendered globally ischaemic for 60 min. This was followed by 60 min of reperfusion. R75231 (0.1 mg.kg-1, intravenously) was given to donor and support rabbits 1 h before the experiment, control rabbits receiving the same volume of vehicle. RESULTS: Treatment with R75231 resulted in a 45% reduction in coronary vascular resistance in aerobically perfused control hearts, an effect that was absent during postischaemic reperfusion. Thus, before ischaemia, coronary flow was greater in R75231 treated hearts [6.6(SEM 0.8) ml.min-1] than in controls [4.3(0.6) ml.min-1; p < 0.05] but during reperfusion no significant difference was observed [4.0(0.6) v 3.6(0.3) ml.min-1]. The mean time to onset and extent of contracture during ischaemia was similar in R75231 treated and control groups, at 42(4) v 41(4) min and 27(3) v 26(6) mm Hg, respectively. Left ventricular developed pressure recovered to approximately 50% of its preischaemic value during the first 40 min of reperfusion in both groups; however, after longer durations of reperfusion, it tended to deteriorate in the R75231 treated group whereas it was maintained at a constant level in the controls [37(10) v 53(6) mm Hg, respectively; NS]. At the end of reperfusion, tissue adenosine content was 13-fold greater in the R75231 treated group, at 0.40(0.09) v 0.03(0.01) mumol.g-1 dry wt in controls; p < 0.05; the nucleotide pool, nicotinamide adenine dinucleotide phosphate content, and the energy charge potential were similar in groups. CONCLUSIONS: R75231 decreased coronary vascular resistance and increased coronary flow during aerobic perfusion in control hearts, an effect that was lost after ischaemia and reperfusion. R75231 also increased greatly the tissue content of adenosine but, despite this, failed to improve either the recovery of cardiac contractile function or the replenishment of the adenine nucleotide pool.

Cardiotrophin-1 protects the human myocardium from ischemic injury. Comparison with the first and second window of protection by ischemic preconditioning.

BACKGROUND: There are reports suggesting that cardiotrophin 1 (CT-1) is cytoprotective. We investigated the cardioprotective effects of CT-1 on the human myocardium and compared this benefit with the early and delayed protection afforded by ischemic preconditioning (PC). METHODS: Right atrium specimens were prepared and incubated in buffer solution at 37 degrees C for 30 min stabilisation, before entering one of the three following studies. In study 1, muscles (n=6/group) were allocated to one of four groups: (i) aerobic control - incubated in oxygenated media for 210 min, (ii) ischemia alone - 90 min ischemia followed by 120 min reoxygenation, (iii) PC by 5 min ischemia-5 min reoxygenation before 90 min ischemia-120 min reoxygenation and (iv) CT-1 (1 nM) - 90 min ischemia-120 min reoxygenation with exposure to CT-1 throughout the protocol. In study 2, muscles (n=6/group) were allocated to one of four protocols as in study 1with the exception that were incubated for 24 h followed by 30 or 90 min ischemia-120 min reoxygenation on day 2. In study 3, the same groups were employed as in study 2 with the exception that only a 30-min period of ischemia was used and that CT-1 antibody (5 microg/ml) was added to all groups throughout the experimental protocol. Creatine kinase (CK, U/g wet wt.) leakage into the medium and MTT reduction (OD/mg wet wt.), an index of cell viability, were assessed at the end of the experiment. RESULTS: In study 1, a first window of cardioprotection was observed with PC (CK=4.39+/-0.34; MTT=0.58+/-0.03 vs. CK=7.11+/-0.4;MTT=0.32+/-0.02 in the ischemic alone group; P<0.001) but not with CT-1(CK=6.65+/-0. 67; MTT=0.31+/-0.03, P=NS vs. ischemia alone). In study 2, PC applied on day 1 was protective against 30-min ischemia (CK=3.28+/-0. 43; MTT=0.68+/-0.046, P<0.001 vs. ischemia alone) but not against 90-min ischemia (CK=7.13+/-0.66; MTT=0.24+/-0.03, P=NS vs. ischemia alone) induced on day 2 (second window). However, when the tissue was exposed to CT-1 for 24 h, protection was similar to that of PC when subjected to 30 min of ischemia (CK=2.95+/-0.71; MTT=0.77+/-0. 05, P=NS vs. PC) and greater than PC when subjected to 90 min of ischemia (CK=4.56+/-0.51; MTT=0.39+/-0.03, P=0.002 vs. PC). In study 3, the CT-1 antibody did not affect the protection induced by PC (CK=3.36+/-0.6; MTT=0.69+/-0.06) but it abolished the protection obtained with CT-1(CK=5.15+/-0.81; MTT=0.42+/-0.06, P=NS vs. ischemia alone group). CONCLUSIONS: CT-1 exhibits a significant protection of the human myocardium against ischemic injury when tissue is exposed to this factor for a long period (e.g. 24 h) but not when exposed for a short period (e.g. 2 h). In addition, the protection afforded by long exposure to CT-1 is as potent or even greater than the one obtained by the second window of PC. The protection induced by CT-1 but not that induced by PC can be abolished by CT-1 antibody suggesting that their beneficial action is attained by different mechanisms.

Myocardial reperfusion in the pig heart model: infarct size and duration of coronary occlusion.

The effect of coronary artery reperfusion on infarct size was studied in a pig heart model. Forty four open chest pigs underwent occlusion of the mid-left anterior descending artery. Fifteen minutes after occlusion the animals were randomised to one of five groups: reperfusion at 30, 45, 60, or 90 min after occlusion (groups 1-4) or permanent occlusion (group 5). Twenty four hours after coronary occlusion the pigs were killed. The heart was sectioned in slices, which were incubated in triphenyl-tetrazolium. Mean(SEM) infarct sizes calculated by planimetry were 0.46(0.42), 2.85(1.14), 9.74(1.65), 8.93(1.37), and 13.17(1.17)% of left ventricular mass in the five groups. The transmural extension of the infarct was 14.6(11.4), 42.1(12.9), 87.4(6.6), 96.2(3.2), and 100(0)% and a transmurality index used as an estimate of the mean extension of the infarct relative to wall thickness was calculated to be 0.08(0.06), 0.32(0.10), 0.72(0.06), 0.79(0.04), and 0.92(0.02) respectively. Infarct size was similar in groups 3-5, but significantly smaller in groups 1 and 2 (p less than 0.05). Infarct size and the transmurality index correlated exponentially with the duration of the occlusion (r = 0.80, p less than 0.01; and r = 0.95, p less than 0.001 respectively). These results indicate that in the pig heart model submitted to an acute coronary occlusion cell viability may be less than that suggested by previous canine studies. This observation is probably related to a less well developed collateral blood flow in the pig heart and may provide an experimental model that better resembles certain clinical conditions.

alpha1-Adrenoceptors during simulated ischemia and reoxygenation of the human myocardium: effect of the dose and time of administration.

OBJECTIVE: We sought to investigate the effect of alpha1-adrenoceptor activity on the ischemic and reoxygenated human myocardium. METHODS: Right atrial appendages (n = 6 per group) obtained during elective cardiac operations were sliced and stabilized in normoxic normothermic buffer solution for 30 minutes and then subjected to 90 minutes of simulated ischemia, followed by 120 minutes of reoxygenation. In study 1 the dose responses to the alpha1-adrenoceptor agonist phenylephrine (0.01, 0.1, 1, 10, and 100 micromol/L) and to the alpha1-adrenoceptor antagonist prazosin (0.1, 1, 10, and 100 micromol/L) when administered for 10 minutes before ischemia, during ischemia, and during reoxygenation were examined. The influence of the time of administration (ie, before ischemia, during ischemia, or during reoxygenation) of phenylephrine (0.1 micromol/L) and prazosin (10 micromol/L) was then investigated in study 2. In study 3 the effect of the combined administration of phenylephrine given before ischemia and prazosin given during ischemia was investigated. In study 4 the protective effect of phenylephrine given before ischemia (for 10 minutes or for 5 minutes with a 5-minute washout period) was compared with that of ischemic preconditioning (5 minutes of ischemia and 5 minutes of reoxygenation). At the end of each protocol, the leakage of creatine kinase (in units per gram of wet weight) and the reduction of 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide to insoluble formazan dye (in millimoles per gram of wet weight) were measured. RESULTS: Phenylephrine is maximally beneficial at 0.1 and 1 micromol/L (creatinine kinase, 0.97 +/- 0.06 and 0.95 +/- 0.03 U/g, respectively; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 153.0 +/- 7.8 and 156.2 +/- 6.7 mmol/g, respectively) compared with ischemic control (creatine kinase, 1.87 +/- 0.03 U/g; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 108.5 +/- 6.8 mmol/g; P <.05) but prazosin is detrimental at concentrations above 10 micromol/L (creatine kinase, 5.22 +/- 0.29 U/g; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 69.8 +/- 2.9 mmol/g; P <.05 vs ischemic control). In addition, phenylephrine (0.1 micromol/L) is protective when given before ischemia (creatine kinase, 2.06 +/- 0.21 U/g; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 148.5 +/- 4.5 mmol/g; P <.05 vs ischemic control) but is detrimental when given during ischemia alone (creatine kinase, 4.49 +/- 0.98 U/g; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 70.5 +/- 6.1 mmol/g; P <.05 vs ischemic control) and has no significant effect during reoxygenation. In contrast, prazosin (10 micromol/L) is beneficial when given during ischemia alone (creatine kinase, 1.34 +/- 0.10 U/g; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 148.5 +/- 4.5 mmol/g; P <.05 vs ischemic control), is detrimental when given during reoxygenation alone (creatine kinase, 1.5 +/- 0.16 U/g; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 85.0 +/- 4.7 mmol/g; P <.05 vs ischemic control), and has no effect when given before ischemia. The use of phenylephrine before ischemia alone is as protective as prazosin given during ischemia alone, but the combination of the two drugs does not cause additional benefit. Interestingly, the protection afforded by phenylephrine when given before ischemia is similar to that obtained with ischemic preconditioning. CONCLUSIONS: In the human myocardium activation of alpha1-adrenoceptors before ischemia is protective but is detrimental during ischemia, whereas blockade of alpha1-adrenoceptors is beneficial during ischemia but detrimental during reoxygenation. The degree of protection achieved by activation of the alpha1-adrenoceptors before ischemia is similar to that obtained with blockade of alpha1-adrenoceptors during ischemia and that of ischemic preconditioning.

Cardiopulmonary bypass exacerbates oxidative stress but does not increase proinflammatory cytokine release in patients with diabetes compared with patients without diabetes: regulatory effects of exogenous nitric oxide.

BACKGROUND: Cardiopulmonary bypass induces oxidative stress and a whole-body inflammatory reaction that are believed to increase surgical morbidity. OBJECTIVES: Our goal was to investigate the effect of nitric oxide supplementation on bypass-induced oxidative stress and inflammatory reaction in patients with and without diabetes undergoing elective coronary bypass graft surgery. METHODS: Patients with and without diabetes were randomized to receive an infusion of saline solution or the nitric oxide donor nitroglycerin at 1 microg. kg(-1). min(-1) starting 10 minutes before the initiation of cardiopulmonary bypass and then maintained for 4 hours (n = 10 per group). Serial blood samples were taken at various intervals and plasma was analyzed for markers of oxidative stress (lipid hydroperoxides, protein carbonyls, and protein nitrotyrosine) and inflammation (complement C3a, elastase, interleukin 8, and tumor necrosis factor alpha). RESULTS: Cardiopulmonary bypass significantly increased lipid hydroperoxides, protein carbonyls, protein nitrotyrosine, complement C3a, elastase, soluble E-selectin, interleukin 8, and tumor necrosis factor alpha in both groups. Infusion of nitroglycerin significantly reduced the increase in lipid hydroperoxides and protein carbonyls in patients who have diabetes without affecting levels in patients without diabetes. Nitroglycerin infusion markedly reduced protein nitrotyrosine and tumor necrosis factor alpha levels in both groups. In contrast, nitroglycerin infusion significantly increased C3a in patients without diabetes and increased elastase and interleukin 8 levels in patients with diabetes. CONCLUSIONS: Cardiopulmonary bypass induces a greater oxidative stress in patients with diabetes than in those without diabetes, and the inflammatory reaction is qualitatively different in the 2 groups of patients. In addition, nitroglycerin reduces oxidative stress in patients with diabetes and differentially affects the inflammatory response to bypass both in patients with and in those without diabetes. The results have important implications with respect to the use of nitric oxide donors during cardiopulmonary bypass.

Exogenous adenosine accelerates recovery of cardiac function and improves coronary flow after long-term hypothermic storage and transplantation.

Impaired coronary flow during postischemic reperfusion may limit functional recovery. In the present studies we used the heterotopically transplanted rat heart and the isolated working rat heart to assess whether adenosine, given during reperfusion, could improve either the rate or the extent of postischemic recovery. Hearts were arrested (2 minutes at 4 degrees C) with the St. Thomas' Hospital cardioplegic solution and stored by immersion in the same solution for 8 hours at 4 degrees C. Hearts were then transplanted into the abdomen of homozygous recipients. Immediately before reperfusion, adenosine (0.5 ml of a 1 mumol/L solution, equivalent to 0.13 micrograms) was injected into the left ventricle (control rats received an equivalent amount of saline). Hearts were reperfused in vivo for 30 minutes or 24 hours, after which they were excised and perfused (Langendorff) for 20 minutes for the assessment of function. They were then freeze clamped and taken for metabolic analysis. After 50 minutes of reperfusion, left ventricular developed pressure was 75 +/- 5 mm Hg (4 mm Hg end-diastolic pressure) in the adenosine group versus 61 +/- 4 mm Hg in the control group (p less than 0.05); however, after 24 hours function was identical in the two groups (52 +/- 4 versus 52 +/- 3 mm Hg). After 50 minutes of reperfusion coronary flow was greater in the adenosine group (11.0 +/- 0.4 versus 9.7 +/- 0.4 ml/min in control rats; p less than 0.05), a difference that was sustained for 24 hours (12.8 +/- 0.3 versus 11.4 +/- 0.4 ml/min in control rats; p less than 0.05). Adenosine triphosphate and creatine phosphate contents recovered to similar extents in control and adenosine groups after both 50 minutes and 24 hours of reperfusion. In further studies with an identical storage protocol (8 hours at 4 degrees C), hearts were not transplanted but were reperfused with crystalloid medium in the Langendorff mode for 15 minutes (creatine kinase leakage measured) and in the working mode for 180 minutes. In an attempt to mimic the heterotopic transplant protocol, adenosine (1 mumol/L) was included in the perfusion fluid for the first 2 minutes of reperfusion. Similar results to those of the transplant studies were obtained, with coronary flow being consistently improved in the adenosine group; however, this benefit was lost after only 2 hours of reperfusion.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of sodium aspartate on the recovery of the rat heart from long-term hypothermic storage.

We have investigated the reported ability of aspartate to enhance greatly the cardioprotective properties of the St. Thomas' Hospital cardioplegic solution after prolonged hypothermic storage. Rat hearts (n = 8 per group) were excised and subjected to immediate arrest with St. Thomas' Hospital cardioplegic solution (2 minutes at 4 degrees C) with or without addition of monosodium aspartate (20 mmol/L). The hearts were then immersed in the same solution for 8 hours (4 degrees C) before heterotopic transplantation into the abdomen of homozygous rats and reperfusion in vivo for 24 hours. The hearts were then excised and perfused in the Langendorff mode (20 minutes). Addition of aspartate to St. Thomas' Hospital cardioplegic solution gave a small but significant improvement in left ventricular developed pressure, which recovered to 82 +/- 3 mm Hg compared with 70 +/- 2 mm Hg in control hearts (p less than 0.05). However, coronary flow and high-energy phosphate content were similar in both groups. In subsequent experiments hearts (n = 8 per group) were excised, arrested (2 minutes at 4 degrees C) with St. Thomas' Hospital cardioplegic solution containing a 0, 5, 10, 20, 30, 40, or 50 mmol/L concentration of aspartate, stored for 8 hours at 4 degrees C, and then reperfused for 35 minutes. A bell-shaped dose-response curve was obtained, with maximum recovery in the 20 mmol/L aspartate group (cardiac output, 48 +/- 5 ml/min versus 32 +/- 5 ml/min in the aspartate-free control group; p less than 0.05). However, additional experiments showed that a comparable improvement could be achieved simply by increasing the sodium concentration of St. Thomas' Hospital cardioplegic solution by 20 mmol/L. Similarly, if sodium aspartate (20 mmol/L) was added and the sodium content of the St. Thomas' Hospital cardioplegic solution reduced by 20 mmol/L, no significant protection was observed when recovery was compared with that of unmodified St. Thomas' Hospital cardioplegic solution alone. In still further studies, hearts (n = 8 per group) were perfused in the working mode at either high (greater than 80 ml/min) or low (less than 50 ml/min) left atrial filling rates. Under these conditions, if functional recovery was expressed as a percentage of preischemic function, artifactually high recoveries could be obtained in the low-filling-rate group. In conclusion, assessment of the protective properties of organic additives to cardioplegic solutions requires careful consideration of (1) the consequences of coincident changes in ionic composition and (2) the characteristics of the model used for assessment.

Protective effect of nicorandil as an additive to the solution for continuous warm cardioplegia.

Experiments were designed to assess whether (1) nicorandil given before global low-flow ischemia or (2) included in low-flow continuous cardioplegia improved the recovery of cardiac function in the isolated rat heart. The first investigated the effect of nicorandil (2, 10, or 100 mumol/L), given for 3 minutes before 30 minutes of normothermic global ischemia, on recovery after 30 minutes of reperfusion. In aerobically perfused hearts, doses of 10 and 100 mumol/L significantly increased coronary flow; the dose of 100 mumol/L exerted a negative inotropic effect. These doses shortened the time to contractile arrest (282 +/- 18 and 276 +/- 22 seconds versus 354 +/- 16 seconds in the control hearts with unmodified ischemia; p < 0.05 in both instances). Nicorandil also improved the postischemic recovery of coronary flow (79.1% +/- 1.7% and 78.0% +/- 1.6%, respectively, versus 71% +/- 1.8%; p < 0.05). However, there was no significant improvement in recovery of contractile function, creatine kinase leakage, or tissue adenosine triphosphate and creatine phosphate contents. Second, pretreatment with nicorandil (10 mumol/L) was shown to increase susceptibility of the hearts to reperfusion-induced ventricular fibrillation from 0% (n = 8) in control hearts to 50% in the drug-treated group (p < 0.05). Third, nicorandil (10 mumol/L) was added to cardioplegic and noncardioplegic solutions infused into the coronary tree throughout 100 minutes of low-flow (0.7 ml/min) ischemia: in eight of nine control hearts electrical activity was maintained throughout, whereas in all nicorandil-treated hearts electrical activity was suppressed for at least part of the time. Nicorandil also reduced the prevalence of ischemic contracture to 0% during continuous infusion of cardioplegic solution (compared with 30% in nicorandil-free control hearts) and improved the recovery of contractile function after 40 minutes of reperfusion. Thus, in the noncardioplegia groups, left ventricular developed pressure recovered to 77.8% +/- 4.0% versus 51.7% +/- 2.6% in control hearts (p < 0.05) and in the cardioplegia groups to 96.2% +/- 4.2% versus 79.7% +/- 5.5% (p < 0.05). Ventricular compliance (the ventricular volume required to achieve a left ventricular end-diastolic pressure of 4 mm Hg) was better preserved in the nicorandil-containing noncardioplegia group (133 +/- 6 microliters) than in the control group (88 +/- 10 microliters; p < 0.05). In conclusion, nicorandil has been shown to (1) reduce ischemic contracture, (2) lessen the effects of ischemic arrest, and (3) improve the postischemic recovery of contractile function. In this species and preparation it may, however, enhance vulnerability to reperfusion-induced arrhythmias.

Effects of cardioplegia on vascular function and the "no-reflow" phenomenon after ischemia and reperfusion: studies in the isolated blood-perfused rat heart.

The ability of cardioplegia to protect against cardiac contractile dysfunction caused by ischemia and reperfusion is well established. The effects of cardioplegia on vascular injury and the no-reflow phenomenon, however, remain controversial. We used the blood-perfused rat heart to study the effect of St. Thomas' Hospital cardioplegic solution on postischemic endothelium-dependent and endothelium-independent vascular function, the extent of the no-reflow phenomenon, and the temporal relationship between postischemic vascular and contractile function. Isolated rat hearts (16 per group) perfused with blood from a support rat at 60 mm Hg were subjected to 10, 20, 30 or 40 minutes of global ischemia and 40 minutes of reperfusion at 37 degrees C. Eight hearts in each group also received cardioplegia (45 mm Hg for 2 minutes) before ischemia. Left ventricular developed pressure was measured with an intraventricular balloon. At the end of reperfusion, a bolus of 250 micrograms nitro-L-arginine methyl ester was infused to assess endothelium dependent vascular function. After a 20-minute washout, 25 micrograms sodium nitroprusside was infused to assess endothelium-independent vascular function. Fluorescein (1 ml, 1% weight/volume) was then infused to assess no-reflow; this involved freezing the hearts, cutting them into transverse sections (10 x 1 mm), video recording the sections under ultraviolet light, digitizing the images, and analyzing density of fluorescence. No-reflow was defined as a flow of less than 5%. Compared with nonischemic control responses, endothelium-independent vascular function was significantly decreased only after 30 and 40 minutes of ischemia (48.1% +/- 3.8% and 24.3% +/- 7.4%, p < 0.05), but it was significantly protected by cardioplegia (66.6% +/- 3.9% and 64.5% +/- 5.2%, p < 0.05). A significant reduction in endothelium-dependent vascular function was observed after 40 minutes of ischemia (-31.8% +/- 6.6% vs -50.4% +/- 1.6% in control hearts, p < 0.05), and again this was improved by cardioplegia (-45.0% +/- 3.4%, p < 0.05 vs ischemic group). Areas of no reflow were present after 30 and 40 minutes of ischemia (11.9% +/- 6.8% and 33.4% +/- 14.1% of left ventricular mass), and at each time period they were significantly decreased by cardioplegia (0.7% +/- 0.4% and 3.8% +/- 1.6%, p < 0.05). Postischemic contractile dysfunction was observed before any vascular alteration was apparent. After only 20 minutes of ischemia, the postischemic recovery of left ventricular developed pressure fell to 56.7% +/- 4.0%, but both endothelium-dependent vascular function and endothelium-independent vascular function were unaffected. In conclusion, vascular alterations are apparent only after prolonged periods of ischemia, longer than those required to observe contractile dysfunction, and cardioplegia protects against postischemic endothelium-dependent and endothelium-independent vascular dysfunction and reduces the extent of the no-reflow phenomenon.

Continuous warm versus intermittent cold cardioplegic infusion: a comparison of energy metabolism, sodium-potassium adenosine triphosphatase activity, and postischemic functional recovery in the blood-perfused rat heart.

We used metabolic, enzymatic, and functional end points to compare the protective properties of continuous warm and intermittent cold cardioplegic infusion in isolated, blood-perfused rat hearts. After excision, hearts (n = 12 per group) were preserved for 3 hours by one of the following cardioplegic procedures: (1) continuous infusion of warm (37 degrees C) blood cardioplegic solution prepared by mixing Fremes' solution with rat arterial blood in a ratio of 1:4, (2) continuous infusion of warm (37 degrees C) crystalloid cardioplegic solution prepared by mixing Fremes' solution with bicarbonate buffer solution in a ratio of 1:4, or (3) intermittent infusion of cold (20 degrees C) St. Thomas' Hospital cardioplegic solution number 2 infused for 3 minutes every 30 minutes during a 3-hour period of ischemia. In the continuous-infusion cardioplegic groups, the solution was infused through the aorta at a flow rate of 0.8 ml.min-1.gm-1 heart. At the end of the 3-hour preservation period, myocardial sodium-potassium adenosine triphosphatase activity (an index of ion-exchange activity) was assessed in six hearts in each group. The remaining hearts in each group were then aerobically perfused at 37 degrees C with arterial blood (from a support rat) for a further 50 minutes, during which time they were atrially paced at 320 beats/min. At the end of this period, left ventricular developed and end-diastolic pressures were assessed with an intraventricular balloon; the hearts were then freeze-clamped and taken for the measurement of tissue adenosine triphosphate and creatine phosphate content. Hearts (n = 6) aerobically perfused with blood for 50 minutes (no cardioplegic infusion) served as control preparations. At a balloon volume of 180 microliters, the mean final values for left ventricular developed pressure in the continuous warm blood, continuous warm crystalloid, and intermittent cold cardioplegic groups were 98 +/- 5 mm Hg (p < 0.05), 70 +/- 5 mm Hg, and 78 +/- 5 mm Hg, respectively. This was compared with 122 +/- 5 mm Hg in control hearts (p < 0.05 vs the rest). For left ventricular end-diastolic pressure, the corresponding values were 33 +/- 3 mm Hg, 32 +/- 6 mm Hg, and 14 +/- 4 mm Hg (p < 0.05), respectively. The control value was 16 +/- 3 mm Hg (p < 0.05 vs continuous warm blood and continuous warm crystalloid groups). Tissue content of adenosine triphosphate was similarly reduced to approximately 50% of control values in all groups, and creatine phosphate content fully recovered in all groups. Sodium-potassium adenosine triphosphatase activity was poorly preserved in continuous warm crystalloid-treated hearts (0.012 +/- 0.003 vs 0.030 +/- 0.008 mumol inorganic phosphate-mg-1.min-1.

Early effects of hypothyroidism on the contractile function of the rat heart and its tolerance to hypothermic ischemia.

We have investigated the early effects of hypothyroidism on cardiac function and tolerance to hypothermic ischemia. Hypothyroidism was induced by thyroidectomy. Five days after operation, sham-operated and thyroidectomized rats were anesthetized and cardiac function was assessed. At this time, the plasma levels of triiodothyronine and thyroxine had fallen by eightfold and threefold, respectively, in thyroidectomized rats compared with the values in sham-operated rats. In vivo pump function was assessed by measuring mean arterial pressure, cardiac index, and stroke volume index: all were reduced by thyroidectomy (respectively 95 +/- 5 mmHg, 22 +/- 2 ml/min/100 gm body weight and 67 +/- 7 microliters/beat/100 gm body weight versus 112 +/- 4 mm Hg, 35 +/- 1 ml/min/100 gm body weight and 85 +/- 4 microliters/beat/100 gm body weight in the sham-operated group; p < 0.05 in each instance). Systemic vascular resistance index was higher in thyroidectomized than in sham-operated rats (4.4 +/- 0.4 versus 3.1 +/- 0.2 mmHg/ml/min/100 gm body weight; p < 0.05). In vivo indices of contractile function were also reduced by thyroidectomy: maximum rate of left ventricular pressure development fell by almost 50% (5190 +/- 790 versus 9600 +/- 900 mmHg/sec; p < 0.05) and left ventricular developed pressure and heart rate also fell (respectively 92 +/- 8 mmHg and 340 beats/min versus 129 +/- 6 mmHg and 398 +/- 6 beats/min; p < 0.05 in each instance). After excision, hearts were blood-perfused and ex vivo function assessed with intraventricular balloons. Systolic and diastolic functions were significantly impaired in the thyroidectomized group and the myocardial Na(+)-K(+)-adenosinetriphosphatase activity was reduced from a control value of 8.3 +/- 0.3 to 5.8 +/- 0.4 mean integrated extinction x 100. The hearts were then subjected to 2 minutes of cardioplegic infusion, 6 hours of hypothermic (4 degrees C) ischemia, and 40 minutes of reperfusion. In control hearts, left ventricular developed pressure (at an end-diastolic pressure of 8 mm Hg) recovered to 76% of its preischemic value (131 +/- 8 versus 173 +/- 8 mmHg; p < 0.05); in hearts from thyroidectomized rats, left ventricular developed pressure recovered to 81% of its preischemic value (110 +/- 8 versus 136 +/- 12 mmHg; p = not significant), an absolute value that was not significantly different from that in the sham-operated group. Diastolic function recovered to the same extent in both groups.(ABSTRACT TRUNCATED AT 400 WORDS)

Protection against injury during ischemia and reperfusion by acadesine derivatives GP-1-468 and GP-1-668. Studies in the transplanted rat heart.

BACKGROUND: Acadesine (AICAr: 5-amino-4-imidazole carboxamide riboside) has been shown to afford sustained protection against injury during ischemia and reperfusion. The present studies used the heterotopically transplanted rat heart to assess the protective properties of two new acadesine analogs: GP-1-468 and GP-1-668. METHODS AND RESULTS: Hearts were excised, arrested with a 2-minute infusion of cardioplegic solution, and subjected to 4 hours of global ischemia (20 degrees C) with cardioplegic reinfusion for 2 minutes every 30 minutes. The hearts were then transplanted (1 hour of additional ischemia) into the abdomens of recipient rats and reperfused in situ for 30 minutes or 24 hours. The hearts were then excised, perfused aerobically for 20 minutes, and contractile function was assessed. GP-1-468 or GP-1-668 was administered to donor rats (20 mg/kg intravenously, 30 minutes before excision). They were also added to the cardioplegic solution (10 mumol/L for GP-1-468, 5 mumol/L for GP-1-343, the active metabolite of GP-1-668) and were also given to recipient rats (20 mg/kg intravenously, 30 minutes before transplantation, so that the drugs were present during reperfusion). Nine groups of hearts were studied. Three groups of studies were carried out (n = 24 transplants for each group). The first group of hearts was reperfused for 30 minutes, the second group was reperfused for 24 hours, and the third group was transplanted but not reperfused; instead, they were frozen at the end of 5 hours of ischemia and taken for metabolite analysis. Within each group were three subgroups (n = 8 per group) receiving GP-1-468, GP-1-668, or saline solution. In the 30-minute reperfusion group the recoveries of left ventricular developed pressure were 88 +/- 4, 87 +/- 7, and 50 +/- 9 mm Hg, respectively (p < 0.05 versus saline-treated controls); left ventricular volumes (recorded at 12 mm Hg) were 112 +/- 20, 132 +/- 28, and 41 +/- 9 microliters, respectively (p < 0.05 versus saline-treated controls), and coronary flows were 13.1 +/- 0.7, 13.4 +/- 1.0, and 9.9 +/- 0.5 ml/min, respectively (p < 0.05 versus saline-treated controls). In addition to improving functional recovery, the two analogs increased the tissue content of adenosine at the end of the ischemic period (5.4 +/- 0.6 and 7.3 +/- 0.5 mumol/gm dry weight, respectively, versus 2.7 +/- 0.4 mumol/gm dry weight in the saline-treated controls; p < 0.05); however, they did not influence adenosine triphosphate or its catabolites. In the 24-hour reperfusion group the corresponding values were 77 +/- 6 and 88 +/- 6 versus 35 +/- 4 mm Hg for left ventricular developed pressure (p < 0.05), 111 +/- 9 and 121 +/- 11 versus 41 +/- 8 microliters for left ventricular volume (p < 0.05), and 13.7 +/- 0.7 and 13.0 +/- 0.6 versus 11.7 +/- 0.7 ml/min for coronary flow (no significant difference). Thus both analogs afforded an early and comparable degree of protection of contractile function that was sustained even after 24 hours of reperfusion. CONCLUSIONS: Both GP-1-468 and GP-1-668 increase the rate and extent of early postischemic recovery, and this protection is sustained for at least 24 hours. These beneficial actions were associated with an increase of the tissue content of adenosine during ischemia, but they appeared to be independent of the status of the high-energy metabolism.

Metabolic, functional, and histologic characterization of the heterotopically transplanted rat heart when used as a model for the study of long-term recovery from global ischemia.

The objective of this study was to assess the utility of the heterotopically transplanted rat heart as a model in which to assess long-term (0 to 7 days) postischemic recovery. This was achieved by characterizing the metabolic, functional, and histologic changes that occur during the first week after implantation. In the first series of studies (n = 6/group), hearts were subjected to 1 hour of global ischemia at room temperature (21 degrees +/- 1 degree C), during which time they were transplanted into the abdomens of the recipients. A permanently implanted intraventricular balloon was used to measure pressure-volume relationships in the implanted heart 1, 4, 8, 12, and 18 hours and 1, 2, 3, 4, 5, 6, and 7 days after transplantation. Left ventricular developed pressure (70 microliters loading volume) was 125 +/- 14 mm Hg (mean +/- SEM) after 1 hour of reperfusion, declining to 79 +/- 15 mm Hg after 4 hours before increasing to a maximum (158 +/- 14 mm Hg) at 24 hours. The pressure subsequently declined to 108 +/- 16 mm Hg by 3 days, and then remained essentially unchanged for the following 4 days. Heart rate declined to 197 +/- 26 beats/min after 1 hour of reperfusion, recovered to 380 +/- 21 beats/min after 24 hours, and remained above 300 beats/min for the remainder of the experiment. Left ventricular end-diastolic pressure increased progressively to very high levels through the 7-day period (176 +/- 23 mm Hg at 7 days). Analysis of creatine phosphate (CP) and of adenosine triphosphate (ATP) and its breakdown products indicated a loss of high-energy phosphates after 1 hour of ischemia (CP = 4.8 +/- 0.3 mumol/gm dry wt), a recovery to preischemic values after 24 hours (CP = 24.4 +/- 2.5 vs 23.8 +/- 1.3 mumol/gm dry weight in fresh control hearts), and a subsequent decline over the ensuing 6 days (CP = 8.1 +/- 1.5 mumol/gm dry wt at 7 days). In additional studies to assess the functional capacity of the unloaded transplanted heart, hearts were excised 1 hour and 1 day after transplantation and perfused as isolated working preparations: their function was then compared with that of fresh nontransplanted hearts. A time-dependent deterioration of all indices of cardiac function was observed. Morphologic studies of transplanted hearts with and without an inserted and inflated intraventricular balloon revealed a rapid reduction of left ventricular cavity volume during the first 24 hours in hearts without a balloon, and progressive severe fibrosis, endomyocardial necrosis, and inflammation over the 7-day period in hearts in which the balloon was intermittently inflated for functional assessment.(ABSTRACT TRUNCATED AT 400 WORDS)

Long-term hypothermic storage of the mammalian heart for transplantation: a comparison of three cardioplegic solutions.

We have compared the protective properties of three cardioplegic solutions (St. Thomas' Hospital, University of Wisconsin, and Bretschneider) for the long-term hypothermic preservation of the rat heart. Hearts (n = 8 per group) were excised and arrested by an infusion (10 ml at 4 degrees C) of cardioplegic solution. After 4, 6, or 8 hours of storage at 4 degrees C, they were reperfused in the Langendorff mode for 15 minutes and then in the working mode for 20 minutes. After 4 hours of storage, postischemic cardiac output in the St. Thomas' and Wisconsin groups was 68.8 +/- 4.6 and 63.7 +/- 3.0 ml/min, respectively (NS); nonischemic aerobic control cardiac output was 83.2 +/- 2.6 ml/min. In the Bretschneider group, cardiac output was only 43.4 +/- 3.6 ml/min (p less than 0.05 compared to the other groups). Extending storage to 6 or 8 hours led to further decreases in recovery of function in all groups (cardiac output in the St. Thomas' and Wisconsin groups was 53.7 +/- 3.2 and 52.2 +/- 5.1 ml/min after 6 hours and 39.9 +/- 2.2 and 45.8 +/- 2.5 ml/min after 8 hours, respectively; NS). With the Bretschneider solution the cardiac output was again lower (37.6 +/- 3.0 and 22.3 +/- 4.1 ml/min, respectively). Creatine kinase leakage tended to be greater in the Bretschneider group, but adenosine triphosphate and creatine phosphate contents were well preserved in all groups. In further studies, hearts (n = 8 per group) were infused with the three solutions and stored at 4 degrees C for 8 or 10 hours; they were then heterotopically transplanted into the abdomens of homozygous recipients. After 24 hours of reperfusion, the hearts were excised and taken for ex vivo functional and metabolic studies. Recovery of contractile function was similar in all groups, but the tissue content of adenosine triphosphate tended to be greater in the St. Thomas' and Wisconsin groups (15.0 +/- 1.5 and 14.7 +/- 1.0 mumol/gm dry weight in the 8-hour storage groups and 12.1 +/- 1.2 and 11.7 +/- 0.8 mumol/gm dry weight in the 10-hour storage groups, respectively) than in the Bretschneider groups (12.3 +/- 0.9 and 9.1 +/- 1.6 mumol/gm dry weight, respectively). Creatine phosphate content recovered completely in all groups. We conclude that all three solutions afford similar protection to the hypothermically stored rat heart, but that the St. Thomas' Hospital and University of Wisconsin solutions are marginally superior to the Bretschneider solution.