The expression and role of tenascin C in abdominal aortic aneurysm formation and progression.

OBJECTIVES: Up-regulation of tenascin C (TNC), a matricellular protein, produced mainly by vascular smooth muscle cells (VSMC), is associated with the progression and dilation of abdominal aortic aneurysms (AAA). The aims of this study were (i) to evaluate whether serum levels of TNC in patients with AAA patients correlate with aortic diameter and (ii) to clarify the role of TNC in formation and progression of AAA in a murine model. METHODS: In 15 patients with AAA serum levels of TNC were measured and correlated with aortic diameters. Moreover, in a murine calcium chloride AAA model, the impact of TNC deficiency on AAA diameter was evaluated. Finally, human VSMC were incubated with TNC to clarify its regulating potential. RESULTS: In the clinical cohort, there was a trend of correlation between serum TNC levels and AAA diameter (P = 0.055). TNC knock out mice with AAA showed significantly lower diameter ratios compared to the wild-type group (WT) 3 weeks (P < 0.05) and 10 weeks (P < 0.05) after AAA induction. Immunohistochemistry revealed increased TNC expression in aortic tissue from WT with AAA as compared sham-operated mice. Furthermore, WT with AAA showed a more disrupted Elastin structure than TNC knock out mice 10 weeks after AAA induction. In human aortic VSMC, TNC incubation induced expression of remodelling associated proteins. CONCLUSIONS: TNC might play a causative role in the formation, dilation and progression of AAA. Our results indicate that TNC might be a biomarker as well as a potential therapeutic target in the treatment of AAA.

Tenascin-C aggravates ventricular dilatation and angiotensin-converting enzyme activity after myocardial infarction in mice.

AIMS: Tenascin-C (TN-C) is suggested to be detrimental in cardiac remodelling after myocardial infarction (MI). The aim of this study is to reveal the effects of TN-C on extracellular matrix organization and its haemodynamic influence in an experimental mouse model of MI and in myocardial cell culture during hypoxic conditions. METHODS AND RESULTS: Myocardial infarction was induced in TN-C knockout (TN-C KO) and wild-type mice. Six weeks later, cardiac function was studied by magnetic resonance imaging and under isolated working heart conditions. Myocardial mRNA levels and immunoreactivity of TN-C, TIMP-1, TIMP-3, and matrix metalloproteinase (MMP)-9, as well as serum and tissue activities of angiotensin-converting enzyme (ACE), were determined at 1 and 6 weeks after infarction. Cardiac output and external heart work were higher, while left ventricular wall stress and collagen expression were decreased (P < 0.05) in TN-C KO mice as compared with age-matched controls at 6 weeks after infarction. TIMP-1 expression was down-regulated at 1 and 6 weeks, and TIMP-3 expression was up-regulated at 1 week (P < 0.01) after infarction in knockout mice. MMP-9 level was lower in TN-C KO at 6 weeks after infarction (P < 0.05). TIMP-3/MMP-9 ratio was higher in knockout mice at 1 and 6 weeks after infarction (P < 0.01). ACE activity in the myocardial border zone (i.e. between scar and free wall) was significantly lower in knockout than in wild-type mice 1 week after MI (P < 0.05). CONCLUSIONS: Tenascin-C expression is induced by hypoxia in association with ACE activity and MMP-2 and MMP-9 elevations, thereby promoting left ventricular dilatation after MI.

Colony-stimulating factor-1 transfection of myoblasts improves the repair of failing myocardium following autologous myoblast transplantation.

AIMS: Skeletal myoblasts are used in repair of ischaemic myocardium. However, a large fraction of grafted myoblasts degenerate upon engraftment. Colony-stimulating factor-1 (CSF-1) accelerates myoblast proliferation and angiogenesis. We hypothesized that CSF-1 overexpression improves myoblast survival and cardiac function in ischaemia-induced heart failure. METHODS AND RESULTS: Three weeks following myocardial infarction, rats developed heart failure and received intramyocardial injections of mouse CSF-1-transfected or untransfected primary autologous rat myoblasts, recombinant human CSF-1, mouse CSF-1 expressing plasmids, or culture medium. Tissue gene and protein expression was measured by quantitative RT-PCR (reverse transcription-polymerase chain reaction) and western blotting. Fluorescence imaging and immunocytochemistry were used to analyse myoblasts, endothelial cells, macrophages, and infarct wall thickening. Electrocardiograms were recorded online using a telemetry system. Left ventricular function was assessed by echocardiography over time, and improved significantly only in the CSF-1-overexpressing myoblast group. CSF-1-overexpression enhanced myoblast numbers and was associated with an increased infarct wall thickness, enhanced angiogenesis, increased macrophage recruitment and upregulated matrix metalloproteases (MMP)-2 and -12 in the zone bordering the infarction. Transplantation of CSF-1-overexpressing myoblasts did not result in major arrhythmias. CONCLUSION: Autologous intramyocardial transplantation of CSF-1 overexpressing myoblasts might be a novel strategy in the treatment of ischaemia-induced heart failure.

The impact of age on cardiac function and extracellular matrix component expression in adverse post-infarction remodeling in mice.

The aim of this study was to describe the potential associations of the expression of matricellular components in adverse post-infarction remodeling of the geriatric heart. In male geriatric (OM, age: 18 months) and young (YM, age: 11 weeks) OF1 mice myocardial infarction (MI) was induced by permanent ligation of the left anterior descending coronary artery. Cardiac function was evaluated by MRI. Plasma and myocardial tissue samples were collected 3d, 7d, and 32d post-MI. Age and MI were associated with impaired cardiac function accompanied by left-ventricular (LV) dilatation. mRNA expression of MMP-2 (7d: p < 0.05), TIMP-1 (7d: p < 0.05), TIMP-2 (7d: p < 0.05), Collagen-1 (3d and 7d: p < 0.05) and Collagen-3 (7d: p < 0.05) in LV non-infarcted myocardium was significantly higher in YM than in OM after MI. MMP-9 activity in plasma was increased in OM after MI (3d: p < 0.01). Tenascin-C protein levels assessed by ELISA were decreased in OM as compared to YM after MI in plasma (3d: p < 0.001, 7d: p < 0.05) and LV non-infarcted myocardium (7d: p < 0.01). Dysregulation in ECM components in non-infarcted LV might be associated and contribute to adverse LV remodeling and impaired cardiac function. Thus, targeting ECM might be a potential therapeutic approach to enhance cardiac function in geriatric patients following MI.

Tenascin-C promotes chronic pressure overload-induced cardiac dysfunction, hypertrophy and myocardial fibrosis.

AIMS: Left ventricular (LV) hypertrophy is characterized by cardiomyocyte hypertrophy and interstitial fibrosis ultimately leading to increased myocardial stiffness and reduced contractility. There is substantial evidence that the altered expression of matrix metalloproteinases (MMP) and Tenascin-C (TN-C) are associated with the progression of adverse LV remodeling. However, the role of TN-C in the development of LV hypertrophy because of chronic pressure overload as well as the regulatory role of TN-C on MMPs remains unknown. METHODS AND RESULTS: In a knockout mouse model of TN-C, we investigated the effect of 10 weeks of pressure overload using transverse aortic constriction (TAC). Cardiac function was determined by magnetic resonance imaging. The expression of MMP-2 and MMP-9, CD147 as well as myocardial fibrosis were assessed by immunohistochemistry. The expression of TN-C was assessed by RT-qPCR and ELISA. TN-C knockout mice showed marked reduction in fibrosis (P < 0.001) and individual cardiomyocytes size (P < 0.01), in expression of MMP-2 (P < 0.05) and MMP-9 (P < 0.001) as well as preserved cardiac function (P < 0.01) in comparison with wild-type mice after 10 weeks of TAC. In addition, CD147 expression was markedly increased under pressure overload (P < 0.01), irrespectively of genotype. TN-C significantly increased the expression of the markers of hypertrophy such as ANP and BNP as well as MMP-2 in H9c2 cells (P < 0.05, respectively). CONCLUSION: Our results are pointed toward a novel signaling mechanism that contributes to LV remodeling via MMPs upregulation, cardiomyocyte hypertrophy as well as myocardial fibrosis by TN-C under chronic pressure overload.

Inflammation and postinfarct remodeling: overexpression of IkappaB prevents ventricular dilation via increasing TIMP levels.

OBJECTIVE: Nuclear factor-kappa B (NF-kappaB) orchestrates genes involved in inflammation and extracellular matrix (ECM) remodeling following myocardial infarction (MI). The objective of the present study was to investigate the effect of overexpression and mode of function of IkappaB, the natural inhibitor of NF-kappaB, on ECM remodeling in a rat model of MI. METHODS: MI was induced in male Sprague-Dawley rats by ligation of the left anterior descending coronary artery (LAD) and was followed by adenovirus-mediated intramyocardial transfection of IkappaB (n = 26) or LacZ reporter genes (n = 26). Sham-operated animals (n = 14) served as controls. RESULTS: In transthoracic echocardiography 49 days after MI, systolic and diastolic left ventricular dimensions were reduced while fractional shortening was preserved in the treatment group. Additionally, evaluation on the isolated heart showed an attenuated downward shift of pressure-volume relationships in the IkappaB group compared to LacZ. NF-kappaB p65 DNA binding activity was diminished both at 5 and 49 days post-MI in the treatment group. Five days post-MI in the treatment group, protein levels of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta were significantly reduced by 72.6% and 73.2%, respectively, compared to LacZ (p<0.05). In parallel, matrix metalloproteinase (MMP)-2 and MMP-9 levels were reduced 5 days post-MI, with MMP-9 still being decreased 49 days post-MI (p<0.01). In contrast, tissue inhibitors of metalloproteinases (TIMP)-1, -2, and -3 were increased compared to LacZ (p<0.01 and p<0.05, respectively) 5 days post-MI. After 49 days, TIMP-2, -3, and -4 expressions were significantly elevated (p<0.05). CONCLUSION: Reducing NF-kappaB activity via IkappaB overexpression after MI positively influences ECM remodeling by reducing MMP-2 and -9 levels while increasing TIMP-1, -2, -3, and -4 levels. Therefore, IkappaB overexpression prevents ventricular dilation and consequently preserves cardiac function.

Short-term clinical outcomes for intermittent cold versus intermittent warm blood cardioplegia in 2200 adult cardiac surgery patients.

BACKGROUND: Aim of the present study was to compare clinical outcome of intermittent cold (ICC) versus intermittent warm (IWC) blood cardioplegia in different cardiosurgical procedures. METHODS: Two thousand one hundred and eighty-eight patients were retrospectively divided into 5 groups: isolated coronary artery bypass surgery (CABG; N.=1203), isolated aortic valve surgery (AVR; N.=374), isolated mitral valve surgery (MVR; N.=151), combined AVR+CABG (N.=390), and combined MVR+CABG (N.=70). Myocardial protection was performed by ICC (N.=1578) or IWC (N.=610) blood cardioplegia. In logistic regression models the effect of cardioplegia on 30-day mortality, IABP/ECLS (intraaortic balloon-pump/extracorporal life support) implantation, transient neurological deficit, stroke, renal failure, new-onset atrial fibrillation, and troponin T release was estimated. Potential modifications of the effect of cardioplegia by logistic EuroSCORE, cross-clamping time, ejection fraction, and op-status elective versus urgent/emergent were investigated. RESULTS: There were no statistically significant differences between ICC and IWC regarding 30-day mortality (odds ratio [OR]=0.70; 95% CI: 0.39-1.23; P=0.219), IABP/ECLS support (OR=0.60; 95% CI: 0.23-1.55; P=0.294), transient neurological deficit (OR=0.90; 95% CI: 0.65-1.24; P=0.541), stroke (OR=0.79; 95% CI: 0.40-1.54; P=0.495), renal failure (OR=1.07; 95% CI: 0.57-1.99; P=0.825), and atrial fibrillation (OR=0.96; 95% CI: 0.77-1.18; P=0.713) across all 5 groups. Troponin t release was significantly higher in ICC compared to IWC (by 0.029±0.015 ng/mL; P=0.046) in univariate analysis; this effect was lowered by risk-factor adjustment and lost statistical significance. The effect of cardioplegia was not significantly different between groups. In urgent/emergent surgery ICC resulted in a significantly higher 30-day mortality (OR=3.03; P=0.024) compared to IWC. CONCLUSIONS: The comparison of IWC and ICC blood cardioplegia in different cardiosurgical procedures showed no statistical significant difference in myocardial protection. The use of ICC, however, appeared overall associated with a slightly better clinical outcome except in patients undergoing urgent/emergent CABG where IWC led to a reduction in 30-day-mortality.

In vivo and ex vivo functional characterization of left ventricular remodelling after myocardial infarction in mice.

AIMS: The interest in cardiac remodelling (REM) has steadily increased during recent years. The aim of this study was to functionally characterize REM following myocardial infarction (MI) in mice using high-end in vivo and ex vivo methods. METHODS AND RESULTS: Myocardial infarction or sham operation was induced in A/J mice. Six weeks later, mice underwent cardiac magnetic resonance imaging and were subsequently sacrificed for ex vivo measurements on the isolated heart. Thereafter, hearts were trichrome stained for infarction size calculation. Magnetic resonance imaging showed significantly reduced ejection fraction (P < 0.01) as well as increased end-systolic and end-diastolic volumes (P < 0.01) after MI. The mean infarct size was 48.8 ± 6.9% of left ventricle. In the isolated working heart coronary flow (time point 20': 6.6 ± 0.9 vs. 13.9 ± 1.6 mL/min, P < 0.01), cardiac output (time point 20': 17.5 ± 2.6 vs. 36.1 ± 4.3 mL/min, P < 0.01) and pump function (80 mmHg: 2.15 ± 0.88 vs. 4.83 ± 0.76, P < 0.05) were significantly attenuated in MI hearts during all measurements. Systolic and diastolic wall stress were significantly elevated in MI animals. CONCLUSION: This two-step approach is reasonable, since data quality increases while animals are not exposed to major additional interventions. Both the working heart and magnetic resonance imaging offer a reliable characterization of the functional changes that go along with the development of post-MI REM. By combining these two techniques, additional information such as wall stress can be evaluated.

The nitric oxide donor, S-nitroso human serum albumin, as an adjunct to HTK-N cardioplegia improves protection during cardioplegic arrest after myocardial infarction in rats.

OBJECTIVES: Currently available cardioplegic solutions provide excellent protection in patients with normal surgical risk; in high-risk patients, however, such as in emergency coronary artery bypass surgery, there is still room for improvement. As most of the cardioplegic solutions primarily protect myocytes, the addition of substances for protection of the endothelium might improve their protective potential. The nitric oxide donor, S-nitroso human serum albumin (S-NO-HSA), which has been shown to prevent endothelial nitric oxide synthase uncoupling, was added to the newly developed histidine-tryptophan-ketoglutarat (HTK-N) cardioplegia in an isolated heart perfusion system after subjecting rats to acute myocardial infarction (MI) and reperfusion. METHODS: In male Sprague-Dawley rats, acute MI was induced by ligation for 1 h of the anterior descending coronary artery. After 2 h of in vivo reperfusion hearts were evaluated on an isolated erythrocyte-perfused working heart model. Cold ischaemia (4°C) for 60 min was followed by 45 min of reperfusion. Cardiac arrest was induced either with HTK (n = 10), HTK-N (n = 10) or HTK-N + S-NO-HSA (n = 10). In one group (HTK-N + S-NO-HSA plus in vivo S-NO-HSA; n = 9) an additional in vivo infusion of S-NO-HSA was performed. RESULTS: Post-ischaemic recovery of cardiac output (HTK: 77 ± 4%, HTK-N: 86 ± 7%, HTK-N + S-NO-HSA: 101 ± 5%, in vivo S-NO-HSA: 93 ± 8%), external heart work (HTK: 79 ± 5%, HTK-N: 83 ± 3%, HTK-N + S-NO-HSA: 101 ± 8%, in vivo S-NO-HSA: 109 ± 13%), coronary flow (HTK: 77 ± 4%, HTK-N: 94 ± 6%, HTK-N + S-NO-HSA: 118 ± 15%, in vivo S-NO-HSA: 113 ± 3.17%) [HTK-N + S-NO-HSA vs HTK P < 0.001; HTK-N + S-NO-HSA vs HTK-N P < 0.05] and left atrial diastolic pressure (HTK: 122 ± 31%, HTK-N: 159 ± 43%, HTK-N + S-NO-HSA: 88 ± 30, in vivo S-NO-HSA: 62 ± 10%) [HTK-N + S-NO-HSA vs HTK P < 0.05; in vivo S-NO-HSA vs HTK-N P < 0.05] were significantly improved in both S-NO-HSA-treated groups compared with HTK and HTK-N, respectively. This was accompanied by better preservation of high-energy phosphates (adenosine triphosphate; energy charge) and ultrastructural integrity on transmission electron microscopy. However, no additional benefit of in vivo S-NO-HSA infusion was observed. CONCLUSIONS: Addition of the NO donor, S-NO-HSA refines the concept of HTK-N cardioplegia in improving post-ischaemic myocardial perfusion. HTK-N with S-NO-HSA is a possible therapeutic option for patients who have to be operated on for acute MI.

Adenovirus-mediated overexpression of inhibitor kappa B-alpha attenuates postinfarct remodeling in the rat heart.

OBJECTIVE: The transcription factor nuclear factor kappa B (NF-kB) plays an important role in the inflammatory response following myocardial infarction. We hypothesized that NF-kB-blockade in an animal model of acute ischemia reduces the inflammatory response and therefore attenuates ventricular remodeling. METHODS: Myocardial infarcts (MI) were produced in male Sprague-Dawley rats by ligation of the LAD and followed by adenovirus-mediated intramyocardial delivery of inhibitor kappa Balpha-gene (n=10), the physiological inhibitor of the transcription factor nuclear factor kappa B, respectively, of a beta-gal reporter-gene (n=11). Sham-operated animals (n=10) received neither ligation nor gene transfer. Five days after MI IkB-expression levels were determined by western blotting. Seven weeks after MI in vivo cardiac function was evaluated by transthoracic echocardiography. Based on left ventricular endsystolic and enddiastolic diameters ejection fraction and fractional shortening were calculated. Only animals with MI involving more than 30% of the left ventricle were included. Data are given as mean+/-SD. RESULTS: In IkBalpha-transfected hearts IkBalpha-levels were six-fold higher (P<0.05) than in beta-gal transfected hearts. Concerning in vivo hemodynamics IkBalpha-treated hearts showed reduced systolic and diastolic left ventricular dimensions compared to the beta-gal MI-group (systolic 48+/-4 vs. 66+/-3 mm; diastolic 67+/-5 vs. 84+/-6 mm; P<0.01). Consequently fractional shortening (27.8+/-1.5 vs. 20.4+/-4.0%; P<0.01) and ejection fraction (63.4+/-3.6 vs. 49.1+/-8.3%; P<0.05) were preserved in IkBalpha hearts compared to beta-gal MI-hearts. CONCLUSION: It can be concluded that overexpression of IkBalpha leads to an improved cardiac function thereby attenuating postinfarct remodeling.

Myofilament protein carbonylation contributes to the contractile dysfunction in the infarcted LV region of mouse hearts.

AIMS: The region-specific mechanical function of left ventricular (LV) murine cardiomyocytes and the role of phosphorylation and oxidative modifications of myofilament proteins were investigated in the process of post-myocardial infarction (MI) remodelling 10 weeks after ligation of the left anterior descending (LAD) coronary artery. METHODS AND RESULTS: Permeabilized murine cardiomyocytes from the remaining anterior and a remote non-infarcted inferior LV area were compared with those of non-infarcted age-matched controls. Myofilament phosphorylation, sulfhydryl (SH) oxidation, and carbonylation were also assayed. Ca(2+) sensitivity of force production was significantly lower in the anterior wall (pCa50: 5.81 ± 0.03, means ± SEM, at 2.3 µm sarcomere length) than that in the controls (pCa50: 5.91 ± 0.02) or in the MI inferior area (pCa50: 5.88 ± 0.02). The level of troponin I phosphorylation was lower and that of myofilament protein SH oxidation was higher in the anterior location relative to controls, but these changes did not explain the differences in Ca(2+) sensitivities. On the other hand, significantly higher carbonylation levels, [e.g. in myosin heavy chain (MHC) and actin] were observed in the MI anterior wall [carbonylation index (CI), CIMHC: 2.06 ± 0.46, CIactin: 1.46 ± 0.18] than in the controls (CI: 1). In vitro Fenton-based myofilament carbonylation in the control cardiomyocytes also decreased the Ca(2+) sensitivity of force production irrespective of the phosphorylation status of the myofilaments. Furthermore, the Ca(2+) sensitivity correlated strongly with myofilament carbonylation levels in all investigated samples. CONCLUSION: Post-MI myocardial remodelling involves increased myofibrillar protein carbonylation and decreased Ca(2+) sensitivity of force production, leading potentially to contractile dysfunction in the remaining cardiomyocytes of the infarcted area.

Type A dissection and chronic dilatation: tenascin-C as a key factor in destabilization of the aortic wall.

OBJECTIVES: Tenascin-C plays an important role in myocardial and vascular remodelling. We hypothesized that tenascin-C is a key factor in the development of degenerative disease of the ascending aorta, leading to chronic dilatation and acute aortic dissection. METHODS: Ascending aortic wall specimens were obtained during surgery for chronic dilatation (n=52) and acute Type A dissection (n=30). Patients (n=12) undergoing aortic valve replacement served as controls. Tenascin-C expression was evaluated by immunostaining and semi-quantitatively assessed using the ImageJ software. TN-C levels in peripheral blood were determined by enzyme-linked immunosorbent assay. RESULTS: Histological examination showed a clear difference between chronic dilatation and acute dissection. In chronic dilatation, tenascin-C staining was homogenously distributed throughout the media parallel to vascular smooth muscle cells. In acute dissection, a strong staining with a heterogenous and spotty distribution was detected. Control aortas showed no tenascin-C staining. Tenascin-C expression was significantly higher in Type-A dissection compared with chronic dilatation. This was accompanied by a significant elevation of tenascin-C levels in peripheral blood in acute dissection. There was no statistical correlation between the tenascin-C level in peripheral blood and the aortic diameter either in dissection or in dilatation. CONCLUSIONS: Tenascin-C is a marker of progressive destabilization of the aortic wall independent of size in chronic dilatation and acute dissection. Therefore, it might be a valuable tool in guiding intervention strategies in patients with disease of the ascending aorta.

Improved myocardial protection in the failing heart by selective endothelin-A receptor blockade.

OBJECTIVE: Ischemia/reperfusion injury caused by cardioplegic arrest is still a major challenge in patients with reduced left ventricular function. We investigated the effect of chronic versus acute administration of the selective endothelin-A receptor antagonist (ERA) TBC-3214Na during ischemia/reperfusion in failing hearts. METHODS: Male Sprague-Dawley rats underwent coronary ligation. Three days after myocardial infarction (MI), 19 randomly assigned animals (ERA chronic) were administered TBC-3214Na continuously with their drinking water, 29 MI rats received placebo, and 3 rats died during the observation period. Six weeks after infarction, hearts were evaluated in a blood-perfused working heart model during 60 minutes of ischemia and 30 minutes of reperfusion. In 14 MI rats, TBC-3214Na (ERA acute) was added to the cardioplegic solution during ischemia. Thirteen MI rats served as control. RESULTS: At a similar infarct size, postischemic recovery of cardiac output (ERA chronic: 91% +/- 10%, ERA acute: 86% +/- 11% vs control: 52% +/- 15%; P < .05) and external heart work (ERA chronic: 90% +/- 10%, ERA acute: 85% +/- 13% vs control: 51% +/- 17%; P < .05) was significantly enhanced in both TBC-3214Na-treated groups whereas recovery of coronary flow was only improved in ERA acute rats (ERA acute: 121% +/- 23% vs ERA chronic: 75% +/- 13%; control: 64% +/- 15%; P < .05). Blood gas measurements showed enhanced myocardial oxygen delivery and consumption with acute TBC-3214Na therapy. Additionally, high-energy phosphates (phosphocreatine) were significantly higher and transmission electron microscopy revealed less ultrastructural damage under acute TBC-3214Na administration. CONCLUSION: Acute endothelin-A receptor blockade is superior to chronic blockade in attenuating ischemia/reperfusion injury in failing hearts. Therefore, acute endothelin-A receptor blockade might be an interesting option for patients with heart failure undergoing cardiac surgery.

S-nitroso human serum albumin attenuates ischemia/reperfusion injury after cardioplegic arrest in isolated rabbit hearts.

BACKGROUND: Depletion of nitric oxide (NO) is associated with ischemia/reperfusion injury. The novel NO donor, S-nitroso human serum albumin (S-NO-HSA), could bridge NO depletion during reperfusion in cardiac transplantation and minimize ischemia/reperfusion injury. METHODS: In an isolated erythrocyte-perfused working heart model, rabbit hearts were randomly assigned after assessment of hemodynamic baseline values to receive S-NO-HSA (0.2 micromol/100 ml, n = 8), L-arginine (10 mmol/100 ml, n = 8) or albumin (control) (0.2 micromol/100 ml, n = 8). After 20 minutes of infusion, the hearts were arrested and stored in Celsior (4 degrees C) enriched with respective drugs for 6 hours, followed by 75 minutes of reperfusion. Hemodynamic values were assessed and biopsy specimens were taken to determine calcium-ionophore stimulated release of NO and superoxide. RESULTS: During early reperfusion, recovery of cardiac output (75% +/- 6% vs 49% +/- 5%, p < 0.05) and coronary flow (99% +/- 8% vs 70% +/- 5%, p < 0.05) were higher, and myocardial oxygen consumption was reduced in the S-NO-HSA Group compared with Control (4.08 +/- 0.46 ml/min/0.1 kg vs 6.78 +/- 0.38 ml/min/0.1 kg, p < 0.01). At the end of the experiment cardiac output (53% +/- 5% vs 27% +/- 5%, p < 0.01) was higher and left atrial pressure (115% +/- 9% vs 150% +/- 8%, p < 0.05) was lower in the S-NO-HSA Group compared with Control. NO release was increased (1,040 +/- 50 nmol/liter and 1,070 +/- 60 nmol/liter vs 860 +/- 10 nmol/liter, p < 0.01) and superoxide release diminished (31 +/- 5 nmol/liter and 38 +/- 5 nmol/liter vs 64 +/- 5 nmol/liter, p < .01) in the S-NO-HSA and L-arginine Groups compared with Control. CONCLUSION: S-NO-HSA improved hemodynamic functions after prolonged hypothermic cardiac arrest by supplementing NO and thereby decreasing ischemia/reperfusion injury.