Severity of polymicrobial sepsis modulates mitochondrial function in rat liver.

Mitochondrial dysfunction is assumed to be an important contributor to multi organ dysfunction syndrome. Here, the effects of varying degrees of sepsis on hepatic mitochondrial function were investigated. Moderate or more severe sepsis was induced in rats using a colon ascendens stent peritonitis (CASP)-model (16 G and 14 G stent respectively). Respiratory control ratio (RCR) was significantly higher in the 16 G-group and unchanged in the 14 G-group compared with healthy controls. The ADP/O ratio was similar in all groups. Our results indicate that different severities of sepsis differently influence the mitochondrial function, which could be a sign of adaptive reaction.

Wheat germ agglutinin staining as a suitable method for detection and quantification of fibrosis in cardiac tissue after myocardial infarction.

The quantification of fibrotic tissue is an important task in the analysis of cardiac remodeling. The use of established fibrosis staining techniques is limited on frozen cardiac tissue sections due to a reduced color contrast compared to paraffin embedded sections. We therefore used FITC-labeled wheat germ agglutinin (WGA), which marks fibrotic tissue in comparable quality as the established picrosirius red (SR) staining, for the staining of post myocardial infarction scar tissue. The fibrosis amount was quantified in a histogram-based approach using the non-commercial image processing program ImageJ. Our results clearly demonstrate that WGA-FITC is a suitable marker for cardiac fibrosis in frozen tissue sections. In combination with the histogram-based analysis, this new quantification approach is i) easy and fast to perform; ii) suitable for raw frozen tissue sections; and iii) allows the use of additional antibodies in co-immunostaining. 

Ischaemic and morphine-induced post-conditioning: impact of mK(Ca) channels.

BACKGROUND: Mitochondrial calcium-sensitive potassium (mK(Ca)) channels are involved in cardiac preconditioning. In the present study, we investigated whether also ischaemic-, morphine-induced post-conditioning, or both is mediated by the activation of mK(Ca) channels in the rat heart in vitro. METHODS: Animals were treated in compliance with institutional and national guidelines. Male Wistar rats were randomly assigned to one of seven groups (each n = 7). Control animals were not further treated. Post-conditioning was induced either by 3 × 30 s of ischaemia/reperfusion (I-PostC) or by administration of morphine (M-PostC, 1 µM) for 15 min at the onset of reperfusion. The mK(Ca)-channel inhibitor paxilline (1 µM) was given with and without post-conditioning interventions (M-PostC+Pax, I-PostC+Pax, and Pax). As a positive control, we determined whether direct activation of mK(Ca) channels with NS1619 (10 µM) induced cardiac post-conditioning (NS1619). Isolated hearts underwent 35 min ischaemia followed by 120 min reperfusion. At the end of reperfusion, infarct sizes were measured by triphenyltetrazolium chloride staining. RESULTS: In the control group, infarct size was 53 (5)% of the area at risk. Morphine- and ischaemic post-conditioning reduced infarct size in the same range [M-PostC: 37 (4)%, I-PostC: 35 (5)%; each P<0.05 vs control]. The mK(Ca)-channel inhibitor paxilline completely blocked post-conditioning [M-PostC+Pax: 47 (7)%, I-PostC+Pax: 51 (3)%; each P<0.05 vs M-PostC and I-PostC, respectively]. Paxilline itself had no effect on infarct size (NS vs control). NS1619 reduced infarct size to 33 (4)% (P < 0.05 vs control). CONCLUSIONS: Ischaemic- and morphine-induced post-conditioning is mediated by the activation of mK(Ca) channels.

Cyclosporine A administered during reperfusion fails to restore cardioprotection in prediabetic Zucker obese rats in vivo.

BACKGROUND AND AIMS: Hyperglycaemia blocks sevoflurane-induced postconditioning, and cardioprotection in hyperglycaemic myocardium can be restored by inhibition of the mitochondrial permeability transition pore (mPTP). We investigated whether sevoflurane-induced postconditioning is also blocked in the prediabetic heart and if so, whether cardioprotection could be restored by inhibiting mPTP. METHODS AND RESULTS: Zucker lean (ZL) and Zucker obese (ZO) rats were assigned to one of seven groups. Animals underwent 25 min of ischaemia and 120 min of reperfusion. Control (ZL-/ZO Con) animals were not further treated. postconditioning groups (ZL-/ZO Sevo-post) received sevoflurane for 5 min starting 1min prior to the onset of reperfusion. The mPTP inhibitor cyclosporine A (CsA) was administered intravenously in a concentration of 5 (ZO CsA and ZO CsA+Sevo-post) or 10 mg/kg (ZO CsA10+Sevo-post) 5 min before the onset of reperfusion. At the end of reperfusion, infarct sizes were measured by TTC staining. Blood samples were collected to measure plasma levels of insulin, cholesterol and triglycerides. Sevoflurane postconditioning reduced infarct size in ZL rats to 35±12% (p<0.05 vs. ZL Con: 60±6%). In ZO rats sevoflurane postconditioning was abolished (ZO Sevo-post: 59±12%, n.s. vs. ZO Con: 58±6%). 5 mg and 10 mg CsA could not restore cardioprotection (ZO CsA+Sevo-post: 59±7%, ZO CsA10+Sevo-post: 57±14%; n.s. vs. ZO Con). In ZO rats insulin, cholesterol and triglyceride levels were significant higher than in ZL rats (all p<0.05). CONCLUSION: Inhibition of mPTP with CsA failed to restore cardioprotection in the prediabetic but normoglycaemic heart of Zucker obese rats in vivo.

Helium-induced late preconditioning in the rat heart in vivo.

BACKGROUND: A recent study showed that the noble gas helium induces early myocardial preconditioning. Cyclooxygenase-2 (COX-2) has been shown to be an important mediator in the signal transduction of late preconditioning. In the present study, we investigated whether helium induces late preconditioning in a concentration-dependent, time-dependent, or in both manner and whether COX-2 activity, mitochondrial function, or both are involved. METHODS: The study was performed in male Wistar rats and consisted of two parts. In part 1, late preconditioning was achieved by administration of 70%, 50%, 30%, and 10% helium for 15 min 24 h before ischaemia/reperfusion (I/R). Based on the findings of part 1, in additional experiments 30% helium was administered subsequently three and two days before I/R. Furthermore, additional rats were pretreated with the COX-2 inhibitor NS-398 (5 mg kg(-1)) with and without 30% helium. Additional experiments were performed for mitochondrial analysis. RESULTS: Helium concentrations of 70%, 50%, and 30% but not 10% reduced infarct size [He-LPC 70: 37(13)%, He-LPC 50: 34(16)%, He-LPC 30: 40(9)%; each P<0.05 vs CONTROL: 55(8)%, He-LPC 10: 53(4)%; P>0.05 vs CONTROL]. Repeated administration of helium did not further enhance cardioprotection. NS-398 completely abolished cardioprotection by 30% helium [He-LPC 30+NS-398: 57(9)%; P<0.05 vs He-LPC 30] but had itself no effect on infarct size [NS-398: 55(9)%; P>0.05 vs CONTROL]. There were no differences in mitochondrial function after helium preconditioning. CONCLUSIONS: Helium induces late preconditioning. Cardioprotection is already maximal with administration of one cycle of 30% helium and is abolished by functional blockade of COX-2 activity.

Helium-induced early preconditioning and postconditioning are abolished in obese Zucker rats in vivo.

Preconditioning is abolished in the prediabetic Zucker obese rat. It has been shown that prevention of mitochondrial permeability transition pore (mPTP) opening is involved in preconditioning by the noble gas helium. Here, we investigated: 1) whether helium induces pre- and postconditioning in Zucker rats and 2) whether possible regulators of the mPTP [i.e., mitochondrial respiration or the extracellular signal-regulated kinase (Erk) 1/2, Akt/glycogen synthase kinase (GSK)-3beta signaling pathway] are influenced. Anesthetized Zucker lean (ZL) and Zucker obese (ZO) rats were randomized to seven groups. Control animals were not treated (ZL-/ZO-Con). Preconditioning groups (ZL-/ZO-He-PC) inhaled 70% helium for 3 x 5 or 6 x 5 min, and postconditioning groups (ZL-/ZO-He-PostC) inhaled 70% helium for 15 min at the onset of reperfusion. Animals underwent 25 min of ischemia and 120 min of reperfusion. In additional experiments, hearts were excised after the third helium exposure for analysis of mitochondrial respiration and for Western blot analysis of Erk1/2, Akt, and GSK-3beta phosphorylation. Helium reduced infarct size from 52 +/- 3% (mean +/- S.E.) to 32 +/- 2% and 37 +/- 2% in ZL rats (ZL-HE-PC, ZL-He-PostC), respectively, but not in ZO rats [ZO-He-PC, 56 +/- 3%; ZO-He-PC (6x), 57 +/- 4%; and ZO-He-PostC, 51 +/- 3% versus ZO-Con, 54 +/- 3%]. Mitochondrial respiration analysis showed that helium causes mild uncoupling in ZL rats (2.27 +/- 0.03 versus 2.51 +/- 0.03) but not in ZO rats (2.52 +/- 0.04 versus 2.52 +/- 0.03). Helium had no effect on Erk1/2 and Akt phosphorylation. GSK-3beta phosphorylation during ischemia was reduced after helium application in ZL but not in ZO rats. Helium-induced preconditioning is abolished in obese Zucker rats in vivo, probably caused by a diminished effect of helium on mitochondrial respiration.

Hyperglycaemia blocks sevoflurane-induced postconditioning in the rat heart in vivo: cardioprotection can be restored by blocking the mitochondrial permeability transition pore.

BACKGROUND: Recent studies showed that hyperglycaemia (HG) blocks anaesthetic-induced preconditioning. The influence of HG on anaesthetic-induced postconditioning (post) has not yet been determined. We investigated whether sevoflurane (Sevo)-induced postconditioning is blocked by HG and whether the blockade could be reversed by inhibiting the mitochondrial permeability transition pore (mPTP) with cyclosporine A (CsA). METHODS: Chloralose-anaesthetized rats (n=7-11 per group) were subjected to 25 min coronary artery occlusion followed by 120 min reperfusion. Postconditioning was achieved by administration of 1 or 2 MAC sevoflurane for the first 5 min of early reperfusion. HG was induced by infusion of glucose 50% (G 50) for 35 min, starting 5 min before ischaemia up to 5 min of reperfusion. CsA (5 or 10 mg kg(-1)) was administered i.v. 5 min before the onset of reperfusion. At the end of the experiments, hearts were excised for infarct size measurements. RESULTS: Infarct size (% of area at risk) was reduced from 51.4 (5.0)% [mean (sd)] in controls to 32.7 (12.8)% after sevoflurane postconditioning (Sevo-post) (P<0.05). This infarct size reduction was completely abolished by HG [51.1 (13.2)%, P<0.05 vs Sevo-post], but was restored by administration of sevoflurane with CsA [35.2 (5.2)%, P<0.05 vs HG+Sevo-post]. Increased concentrations of sevoflurane or CsA alone could not restore cardioprotection in a state of HG [Sevo-post2, 54.1 (12.6)%, P>0.05 vs HG+Sevo-post; CsA10, 58.8 (11.3)%, P>0.05 vs HG+CsA]. CONCLUSIONS: Sevoflurane-induced postconditioning is blocked by HG. Inhibition of the mPTP with CsA is able to reverse this loss of cardioprotection.

Pharmacological characteristics of the specific transporter for the endogenous cell growth inhibitor agmatine in six tumor cell lines.

BACKGROUND AND AIMS: This study examined agmatine transport into six human intestinal tumor cell lines and compared the pharmacological properties of this transporter with those of the agmatine carrier previously characterized in human glioblastoma cells. METHODS: Carrier-mediated uptake was determined as specific accumulation of [(14)C]agmatine in the cells. The changes in intracellular agmatine concentration in the tumor cells after 24 h incubation with 1 mM agmatine was analyzed by high-performance liquid chromatography. RESULTS: Specific [(14)C]agmatine accumulation was found in the six human intestinal tumor cell lines Caco2, Cx1, Colo320, HT29, Colo205E, and SW480. Specific [(14)C]agmatine accumulation was inhibited by phentolamine, putrescine, spermine, clonidine, and decynium-22 but not by corticosterone, O-methylisoprenaline, or l-carnitine. Incubation with exogenous agmatine for 24 h increased intracellular agmatine content in all cell lines by a multiple of the basal endogenous content. Transfection of HEK293 cells with cDNA encoding either hOCT1, hOCT2, or hOCT3 did not enhance [(14)C]agmatine accumulation compared to nontransfected cells. CONCLUSION: All intestinal tumor cell lines investigated express a functional specific agmatine transporter which exhibit pharmacological characteristics similar to those of the agmatine transporter in glioblastoma cells. This agmatine carrier is not identical with any so far known organic cation transport system.

Additive protective effects of late and early ischaemic preconditioning are mediated by the opening of KATP channels in vivo.

We investigated whether a combination of ischaemic late preconditioning (LPC) and ischaemic early preconditioning (EPC) induces additive myocardial protection in vivo, and the role of ATP-sensitive K (KATP) channels in ischaemic LPC and in LPC + EPC. Sixty rabbits were divided into seven groups. Anaesthetized animals were subjected to 30 min of coronary artery occlusion and 120 min of reperfusion (I/R). Controls (CON, n = 9) were not preconditioned. LPC (n = 10) was induced in conscious rabbits by a 5-min period of myocardial ischaemia 24 h before I/R. The KATP channel blocker 5-hydroxydecanoate (5-HD, 5 mg/kg) was given 10 min before I/R with (LPC + 5-HD, n = 9) or without LPC (5-HD, n = 8). EPC (n = 8) was induced by a 5-min period of myocardial ischaemia 10 min before I/R. Animals received LPC and EPC without (LPC + EPC, n = 8) or with 5-HD (LPC + EPC + 5-HD, n = 8). LPC reduced infarct size (IS, triphenyltetrazolium staining) from 57 +/- 11% (MW +/- SD, CON) of the area at risk to 31 +/- 19% (LPC, P = 0.004). 5-HD did not affect IS (5-HD: 60 +/- 12%, P = 0.002 versus LPC), but abolished the cardioprotective effects of LPC (LPC + 5-HD: 62 +/- 18%, P = 0.001 versus LPC). EPC reduced IS to 18 +/- 8%. Additional LPC led to a further reduction to 8 +/- 4% (LPC + EPC, n = 8; P = 0.005 versus EPC; P = 0.004 versus LPC). 5-HD abolished this additional cardioprotective effect of LPC + EPC (LPC + EPC + 5-HD, n = 8; 46 +/- 11%, P < or = 0.001 versus LPC + EPC). We conclude that the combination of ischaemic LPC and EPC induces additive cardioprotection. KATP channel opening mediates the cardioprotective effects of ischaemic LPC and LPC + EPC.

The combined hydrolysis and hydrogenation of inulin catalyzed by bifunctional Ru/C.

A one-pot process for hydrolysis and hydrogenation of inulin to D-mannitol and D-glucitol over a bifunctional Ru/C catalyst was developed. The hydrolysis is catalyzed by the carbon support, onto which acidity was introduced by pre-oxidation. The effect of different carbon treatments on the hydrolysis of inulin was studied. Oxidation with ammonium peroxydisulfate resulted in a carbon with the highest hydrolysis activity. On this carbon, long chain inulin is hydrolyzed faster than inulin rich in short chains. The application of high pressure (up to 100 bar) increased the hydrolysis rate substantially. The combined process was successfully conducted with a Ru-catalyst supported on this oxidized carbon.

Hydrogenation of fructose on Ru/C catalysts.

The hydrogenation of D-fructose on Ru/C catalysts was studied. Under the conditions applied (1 bar H2, 72 degrees C), the furanose forms of D-fructose react, while the pyranose forms do not. However, all anomers adsorb with comparable strength on the surface. The reaction rate is controlled by product inhibition. The selectivity to D-mannitol can be increased from 47 to 63% by promotion of Pd/C and Pt/C catalysts with Sn.

Psychosocial predictors of low birthweight: a prospective study.

OBJECTIVE: To examine the role of psychosocial risk factors for low birthweight. DESIGN: A prospective study. SETTING: Obstetric outpatient clinics of the University Hospital Vrije Universiteit, Amsterdam. PARTICIPANTS: Three hundred and ninety-six nulliparous women. METHODS: Questionnaires on background variables, daily stressors, psychological and mental wellbeing, social support and work factors were completed by the women in the first, second and third trimester of pregnancy. Low birthweight for gestational age was defined at different cut off points: 1. < or = 10th customised birthweight centile (n = 69); 2. < or = 5th customised birthweight centile (n = 54); 3. < 3rd customised birthweight centile (n = 35); and 4. < or = the 10th Dutch birthweight centile (n = 40). Multivariate logistic regression was applied and the results were expressed in odds ratios and their 95% confidence intervals. RESULTS: When the cut off level was defined < or = 5th and < 3rd customised centile, the number of daily stressors in the first trimester was a statistically significant risk factor (OR 1.04, 95% CI 1.01-1.07 and OR 1.04, 95% CI 1.01-1.08). No significant psychosocial risk factors could be identified when low birthweight for gestational age was defined < or = the 10th customised birthweight centile. When low birthweight for gestational age was defined < or = the 10th Dutch birthweight centile, number of hours housekeeping per week in the first trimester (OR 1.59, 95% CI 1.03-2.46), low subjective severity rating of daily stressors in the first trimester (OR 0.41, 95% CI 0.17-0.97) and depressive mood in the first trimester (OR 1.12, 95% CI 1.01-1.24) were statistically significant psychosocial risk factors after controlling for maternal weight and height, number of cigarettes smoked per day and educational level. CONCLUSIONS: In the first trimester of pregnancy maternal psychosocial factors are associated with an increased risk of low birthweight. The specific psychosocial risk factors found were different when the definition of low birthweight was changed. Therefore, in this field of research, we suggest use of the most valid outcome measure for low birthweight, being the customised birthweight centiles.

Vasoactive mediators in pregnancy-induced hypertensive disorders: a longitudinal study.

OBJECTIVE: The objective of this study was to evaluate the extent to which endothelin and the eicosanoids prostacyclin and thromboxane A2 are involved in the pathophysiology of gestational hypertension and preeclampsia. STUDY DESIGN: In a longitudinal design, venous blood samples and 24-hour urine specimens were collected from 396 women in each trimester of pregnancy. After delivery of all patients, venous plasma endothelin was assessed in 20 subjects with identified preeclampsia, 48 subjects with gestational hypertension, and 59 normotensive subjects. Urinary excretions of the thromboxane A2 and of the prostacyclin metabolites thromboxane B2 and 6-keto-prostaglandin F1 alpha were assessed in 16 subjects with preeclampsia, 35 subjects with gestational hypertension, and 31 normotensive subjects. RESULTS: Endothelin levels showed a second-trimester drop in all groups. In all 3 gestational trimesters a high correlation was found between the excretion of thromboxane B2 and that of 6-keto-prostaglandin F1 alpha (P <.001). The overall thromboxane B2 and 6-keto-prostaglandin F1 alpha urinary excretions increased throughout pregnancy and the overall thromboxane B2 /6-keto-prostaglandin F1 alpha ratio decreased. No significant differences in endothelin, thromboxane B2, and 6-keto-prostaglandin F1 alpha excretion levels or in thromboxane B2 /6-keto-prostaglandin F1 alpha ratios were found between women with preeclampsia, gestational hypertension, and normotension. Only in a small group of patients with severe preeclampsia (n = 2) and severe gestational hypertension (n = 2) were increased second-trimester endothelin values and increased thromboxane B2 /6-keto-prostaglandin F1 alpha ratios found. CONCLUSION: In this longitudinal study we found no evidence for prostacyclin deficiency or increased endothelin levels in preeclampsia. Only women with severe preeclampsia and severe gestational hypertension expressed increased endothelin levels and thromboxane dominance over prostacyclin.

Total plasma fibronectin as a marker of pregnancy-induced hypertensive disorders: a longitudinal study.

OBJECTIVE: To determine normal values of total plasma fibronectin in all three gestational trimesters and to examine 1) whether total plasma fibronectin levels differ between normotensive, hypertensive, and preeclamptic women; and 2) whether total plasma fibronectin may serve as an early marker of pregnancy-induced hypertensive disorders. METHODS: Total plasma fibronectin was measured in 376 nulliparous women once in each trimester of pregnancy. Normotensive controls (n = 222) and subjects with pregnancy-induced hypertensive disorders (n = 154) were identified after delivery. The group with pregnancy-induced hypertensive disorders was subdivided into a gestational hypertensive group (n = 125) and a preeclamptic group (n = 29). A complete total plasma fibronectin data set was obtained from 347 subjects. Trends in total plasma fibronectin values were compared for the different groups and relative risks (RRs) were calculated after optimal cutoff levels had been determined by receiver operating characteristic curves. RESULTS: Total plasma fibronectin values (+/- standard error of the mean) were 227 +/- 3 mg/L in the first, 219 +/- 3 mg/L in the second, and 260 +/- 5 mg/L in the third trimesters in normotensive pregnancies. In the first trimester and persisting throughout pregnancy, total plasma fibronectin levels were significantly higher in patients with pregnancy-induced hypertensive disorders than in controls and showed a sharper increase throughout pregnancy. Increased first-trimester total plasma fibronectin levels result in an RR of 1.4 (95% confidence interval [CI] 1.1, 1.8) of developing a pregnancy-induced hypertensive disorder in general. The RR for the development of preeclampsia was 1.7 (95% CI 0.9, 3.4), which was not significant, when the first-trimester total plasma fibronectin level was above the cutoff level of 240 mg/L. The RR for developing preeclampsia was 3.8 (95% CI 1.8, 8.0) when the second-trimester total plasma fibronectin level increased above 230 mg/L. CONCLUSION: The findings of the present study confirm those of previous studies that have found increased total plasma fibronectin levels in pregnancy-induced hypertensive disorders. This study discovered that in these women, total plasma fibronectin levels are elevated in the first trimester. Total plasma fibronectin appears to be a poor predictor of preeclampsia when measured in a general pregnant population. Therefore, total plasma fibronectin should not be used as a routine screening test in a low-risk population. However, obstetricians may use total plasma fibronectin values to help determine the relative risk of developing pregnancy-induced hypertensive disorders.

Psychosocial factors as predictors of maternal well-being and pregnancy-related complaints.

The aim of the current study was to investigate the effects of psychosocial variables on well-being and on pregnancy-related complaints throughout pregnancy. Three hundred and ninety-six nulliparous women completed questionnaires on number of daily stressors, social support, gestational factors and mental and physical work load in each trimester of pregnancy. In addition, the following dependent measures were assessed: depression, anxiety, somatic complaints, and the pregnancy-related complaints fatigue, nausea and back pain. The independent variables predicted depression best (r2 = 42-44%), followed by anxiety (R2 = 13-20) and somatic complaints (R2 = 16-21%). Number of daily stressors explained most of the variance. Satisfaction with social support and maternal age were negatively correlated with depression. In contrast, pregnancy-related complaints could be less accurately predicted by psychosocial factors. The amount of explained variance for fatigue ranged between 6 and 10%, for nausea between 2 and 6%, and for back pain between 5 and 7% for the three trimesters. It is concluded that depressive symptoms during pregnancy are associated with negative psychosocial factors, particularly the number of daily stressors and low satisfaction with received social support. To a lesser degree, this is also the case with anxiety and somatic complaints. Pregnancy-related complaints, on the other hand, appear to be relatively independent of psychosocial conditions.

[Semi-automatic TNM classification of malignant tumors with the ESTER system exemplified by the larynx]. / Semiautomatische TNM-Klassifikation maligner Tumore mit dem ESTHER-System am Beispiel des Kehlkopfs.

Classification of tumours according to the TNM scheme has been accepted worldwide. However, vague baseline assessments and borderline cases render a comparison of the outcome on the basis of TNM classification impossible. Therefore we integrated the TNM rules as a new algorithm into an existing expert system for determining therapy. Thus, every tumour documented with the ESTHER system is automatically classified according to current TNM rules. The program is designed to cope with future changes of the TNM system: raw data are used for classification so that only the algorithms need to be modified.

Students' preferences for service delivery: pull-out, in-class, or integrated models.

This study assessed students' preferences about where and by whom they receive instruction for learning difficulties. Subjects were 686 special, remedial, and regular education students in grades 2, 4, and 5, from classrooms that used a pull-out, in-class, or integrated model for specialized instruction. Results of student interviews indicated that children's preferences for in-class and pull-out services were affected by the service delivery model used in their classroom and their grade level. The majority of children preferred to receive additional help from their classroom teacher rather than from a specialist.

Haemodynamic and antiarrhythmic protective effects of intracoronary perfusion during percutaneous transluminal coronary angioplasty.

In 17 anaesthetized open-chest pigs, experiments were performed to determine if a myocardial protective effect can be obtained by intracoronary perfusion through the dilatation catheter during balloon inflation for percutaneous transluminal coronary angioplasty. Placement of the catheter such that the balloon lay in the middle third of the left anterior descending coronary artery caused a significant deterioration in haemodynamic status prior to balloon inflation, and on 5 occasions led to the development of ventricular fibrillation (VF). Balloon inflation without perfusion for periods of up to 5 min produced further haemodynamic deterioration, and culminated in VF in 4/14 cases. Simultaneous perfusion during balloon inflation (proximal perfusion pressure 900-1200 mmHg), with flow rates of 14.5 ml min-1 for arterial whole blood and 21 +/- 7 ml min-1 for blood diluted with 0.90% NaCl (haematocrit approx. 25%), not only prevented the haemodynamic deterioration but resulted in an improvement compared with values obtained with the catheter in position prior to balloon inflation. In no case did VF occur during 5 min of balloon inflation plus perfusion. The use of diluted blood as the perfusate was not associated with intracatheter thrombus formation, which was sometimes seen as a complication of whole blood perfusion.