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Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): The Russian Science Foundation Introduction Aortic valve stenosis due to calcification of valve cusps is the most common valve disease in the world today. The main feature of this condition is a progressive mineralization of valve tissue. The mechanisms underlying this process is still unknown, but in recent years it has become clear that pathological mineralization of heart and blood vessels has some similarities with the physiological process of bone formation. It has been suggested that interstitial cells (VICs) are the main functional units in the valve that undergo calcification. However, the early initiating mechanisms that trigger osteogenic transformation of cells remain unclear. Purpose The aim of the present study was to elucidate the most responsive time point of osteogenic differentiation induction and to identify the main osteogenic markers that mediate pathological calcification in human aortic valve. Methods VICs were obtained from patients with aortic valve calcification and from healthy aortic valves. The effectiveness of cell cultures osteogenic differentiation was estimated by Alizarin Red staining. Investigation of gene expression changes upon osteogenic differentiation was performed by qPCR and RNA sequencing. Results We found that 48 hours after the induction of osteogenic differentiation is the most relevant time point to identify the early regulators of osteogenic transformation of the cells. That is the time when the most intensive response from osteogenic markers takes place – BGLAP, OPG, OGN, RUNX2 – in comparison to 24, 72 and 96 hours of differentiation in both patient’s and healthy cells. We found out that induction of osteogenic differentiation on early stages initiates transcriptional program that serve to induce the next molecular events which recruit phenotype-specific osteogenes. We revealed that 558 and 232 genes which were up and down regulated during differentiation were the same for healthy and patient’s cells. However, there was a number of genes which was specific for either patient’s or healthy cells. Conclusions We presume that a great amount of the main molecular participants of osteogenic differentiation is shared between different types of cells which are prone to differentiation. However, we perform the results about specificity and difference between the mechanisms of osteogenic differentiation of patient’s and healthy cells.

Aim: Ischaemic preconditioning (IPC) has been demonstrated to protect heart function and viability, but has been predominantly studied in male animals. Methods: We studied a possible influence of sex and oestrogen for protection in IPC. Infarct size and heart function after 40 min global ischaemia and 60 min reperfusion with or without preceding classic IPC was investigated in Langendorff-perfused hearts. Hearts were harvested from 10-week-old male and female C57BL6 mice with or without gonadectomy 6 weeks earlier, or gonadectomy and substitution with 17β-oestradiol for 4 weeks (n = 104). Results: Classic IPC reduced depression of left ventricular developed pressure (P

The effects of H290/51, a novel indenoindole derivative inhibitor of lipid peroxidation, on ultrastructural changes during cardiac ischemia-reperfusion injury were investigated. Langendorff-perfused rat hearts were exposed to 30 minutes of global ischemia followed by 20 minutes of reperfusion: Group A: Control hearts with standard buffer perfusion with vehicle added. Group B: H290/51 (10(-6) mol/l) added to buffer throughout stabilisation and reperfusion. In an additional Group C, where hearts were given H290/51, but not subjected to ischemia, the ultrastructure was preserved till the end of reperfusion. Absolute volumes and calculated volume fractions (Vv) of tissue and subcellular components were assessed with quantitative stereologic morphometry. After ischemia the increase in volume of extracellular interstitium was inhibited by H290/51 (247 +/- 80 vs. 159 +/- 50 microl, mean +/- SD, groups A and B, respectively, p

Cardiac troponin T (cTnT) is a highly sensitive and specific serum marker of irreversible cardiomyocyte injury. It is not clear whether cTnT also is a suitable marker of subtle, reversible injury. In the present investigation the relationship between cTnT release and function during the first 30 min of reperfusion after 30 min of global ischaemia, was investigated in isolated, retrogradely perfused rat hearts. Left ventricular systolic (LVSP), end-diastolic (LVEDP) and developed (LVDP) pressures, heart rate (HR), and coronary flow (CF) were measured. In one series of experiments (n=7) the kinetics of cTnT release during 30 min of reperfusion was investigated. An early, short-lasting peak of cTnT release appeared after 30 s of reperfusion. Then cTnT release gradually increased with a maximum after 20 min (from 0.08 +/- 0.03 before ischaemia to 2.16 +/- 0.40 ng min-1) (mean +/- SEM). In a second series of experiments (n=52) the relationship between cTnT release and cardiac function was investigated after 20 min of reperfusion. At this time point LVEDP increased (0 to 62 +/- 3 mmHg) and LVDP decreased (84 +/- 2 to 33 +/- 3 mmHg), but without any correlation with cTnT release. cTnT release was positively correlated to LVSP (P < 0.04, r=0.29), and negatively correlated to HR (P < 0.03, r=-0.31). cTnT concentration in the coronary effluent increased in parallel to increasing CF (P < 0.03, r=0.31). In conclusion, during the early reperfusion period there was no consistent correlation between cTnT release and dysfunction after global ischaemia in the isolated rat heart. Release of cTnT and post-ischaemic function appear to provide supplementary information in this particular model.

This study tested the therapeutic efficacy of doxorubicin hydrochloride in two formulations: free in saline suspension and encapsulated in polyethylene glycol-coated, long-circulating liposomes. The drug formulations at a dose level of 3 mg doxorubicin per kg body weight were injected intravenously to treat the human pancreatic carcinoma AsPC-1, implanted s.c. into nude Swiss mice. Liposome-encapsulated doxorubicin was significantly more effective in inhibiting tumour growth and in effecting cures, and had only minor systemic toxic side-effects, indicated by a transient weight loss. Confocal laser scanning microscopy was used to determine the tumour uptake and the clearance of doxorubicin in the free and in the liposomal forms. The liposome-encapsulated doxorubicin entered the tumour in greater quantity, and remained in the tumour longer, than the free drug. The liposome formulation produced a sixfold or greater increase in doxorubicin at the disease site. It is probable that increased penetration into the tumour, and long presence with slow drug release from liposomes in the tumour, account for the enhanced therapeutic effect when the drug was encapsulated in polyethylene glycol-coated liposomes. Images Figure 2

In studies of preconditioning, a variety of models have been used. The aim of the present study was to find the optimal preconditioning model for preservation of cardiac function during reperfusion of globally ischaemic, Langendorff-perfused rat hearts. Cardiac function was assessed by the occurrence of severe reperfusion arrhythmias (ventricular fibrillation or asystolia), heart rate (HR), left ventricular systolic (LVSP), end diastolic (LVEDP), and developed pressures (LVDP = LVSP - LVEDP), as well as coronary flow (CF). Series 1 (n = 17) in each group: control perfusion for 20 min without preconditioning or 2 episodes of 2, 3, 4, or 5 min of ischaemia, each followed by 5 min reperfusion, before 25 min ischaemia and 60 min reperfusion. Preconditioning reduced the incidence of reperfusion arrhythmias, attenuated the reperfusion-induced increase of LVEDP, and increased CF, but did not influence LVSP, LVDP, or rate x pressure-product (RPP = LVSP x HR) during reperfusion. The greatest effect was found by 2 min ischaemia and 5 min reperfusion. In series 2 (n = 17 in each group) control perfusion for 7 or 28 min, or preconditioning with 1-4 episodes of 2 min ischaemia and 5 min reperfusion before 35 min ischaemia and 60 min reperfusion were compared. Reduction of severe reperfusion arrhythmias and LVEDP elevation, as well as improvement of CF, LVDP, and HR in preconditioned hearts were observed in series 2. Optimal cardioprotection was achieved by only one episode of preconditioning. In conclusion, preconditioning before global ischaemia improved cardiac function during reperfusion of isolated rat hearts. The most marked effects were reduction of severe reperfusion arrhythmias and attenuation of diastolic dysfunction. Although all preconditioning models employed were cardioprotective, 1 episode of 2 min ischaemia provided optimal protection.

The effects of methylprednisolone (MP) on the acute airway and pulmonary vascular responses induced by reactive oxygen species (ROS) were investigated in isolated, plasma-perfused rat lungs. ROS were generated by adding xanthine oxidase and hypoxanthine to the perfusate. MP was administered in 3 different ways: 1. Added to the perfusate (1 mg*ml-1) 5 min prior to xanthine oxidase and hypoxanthine, 2. Given as intraperitoneal injections (40 mg*kg-1) to lung donor rats 12 and 2 hours prior to the experiments, or 3. Combining 1 and 2. The lungs were perfused at constant volume inflow (15 ml*min-1). Pulmonary arterial pressure and transpulmonary pressure were followed for 30 min after addition of xanthine oxidase and hypoxanthine. ROS induced a powerful, acute broncho- and vasoconstriction, which was inhibited by addition of MP to the perfusate. Pretreatment with MP also inhibited the vascular and airway responses. Adding MP to the perfusate of pretreated lungs further reduced the ROS-induced smooth muscle constriction. In conclusion, MP inhibits vasoconstriction and bronchoconstriction induced by ROS in isolated rat lungs.

The role of histamine in cardiac physiology and pathophysiology is not clarified, but is dependent on species. The effects of exogenous histamine in Langendorff-perfused rat hearts were investigated. 1 mM, 100, 10, 1 and 0.1 microM of histamine (n = 7 each) as 15 min infusions were employed in a dose-response study, and compared to control perfused hearts (n = 7). In another experimental series, 100 microM histamine (n = 15) was added during reperfusion after 25 min global ischemia, and compared to control ischemia-reperfusion (n = 15). The maximal response to histamine in the dose-response study (100 microM) was an increase of left ventricular developed pressure to 126 +/- 8% of initial value (mean +/- SEM, p0.04), and increase of coronary flow to 152+6% (p0.02) after 5 min infusion. 100 microM histamine did not significantly influence heart rate or rhythm. The lowest concentration (0.1 microM) did not have effects cardiac performance. Reperfusion with histamine for 2 min after ischemia reduced left ventricular developed pressure to 68 +/- 10% of initial value versus 116+17% in ischemic controls (p0.05), and increased left ventricular end-diastolic pressure to 24 +/- 8 mmHg compared to 6 +/- 2 mmHg in controls (p0.04). Left ventricular pressures were similar in hearts reperfused with histamine and in ischemic controls for the rest of the observation. Coronary flow increased during reperfusion in hearts given histamine. Histamine had a dose-dependent positive inotropic and vasodilatory effect in isolated rat hearts. Exogenous histamine had only minor effects on post-ischemic cardiac function.

Doxil® (Stealth® liposomal doxorubicin HCl) Injection is doxorubicin HCl incorporated into long circulating liposomes that contain surface-grafted polyoxyethylene chains. These surface-grafted poly...

The role of arachidonic acid metabolites in the cardiac effects of toxic oxygen metabolites (TOM) was investigated in buffer-perfused rat hearts (Langendorff model). Hydrogen peroxide (H 2 O 2 , 200 μM) was given for 10 min to generate TOM, followed by 30 min recovery. H 2 O 2 reduced left ventricular developed pressure (LVDP), increased left ventricular end-diastolic pressure (LVEDP), and increased coronary flow (CF). The hydroxyl radical scavenger thiourea inhibited the H 2 O 2 -induced effects. Perfusion with three lipoxgenase inhibitors, AA861, BWA4C, and diethylcarbamazine, in adition to H 2 O 2 , augmented the decrease of LVDP and the increase of LVEDP induced by H 2 O 2 . The cyclooxygenase inhibitor indomethacin had the same effects. The H 2 O 2 -induced increased in CF was not influenced by diethylcarbamazine, but inhibited by all other drugs. Control perfusion with drugs alone did not influence cardiac function. In conclusion, inhibition of lipoxygenase and cyclooxygenase augmented the depression of cardiac function induced by TOM. Leukotrienes and prostanoids appear to be protective against H 2 O 2 -induced cardiac injury.

Tissue plasminogen activator (t-PA) is a marker of endothelial cell injury or activation. The release of t-PA from isolated rat hearts (Langendorff model) subjected to ischemia-reperfusion or reactive oxygen intermediates (ROI) generated by H2O2 was investigated. H2O2 (200 microM) increased t-PA activity in the coronary effluent to 305 +/- 84% of initial value (mean +/- SEM, p0.04 vs controls) at the end of a 10 min intervention. The hydroxyl radical scavenger thiourea (10 mM) only partially inhibited the increase (175 +/- 27%, p0.01 compared to controls). 20 min normothermic ischemia increased t-PA activity to 416 +/- 108% (p0.005 compared to controls) at the start of reperfusion. In conclusion, cardiac injury by ischemia-reperfusion or ROI increases release of t-PA.

In a double-blind study 18 patients were randomized to receive a daily dietary supplement of concentrated ethyl ester compound of n-3 fatty acids or placebo (corn oil) for at least 6 weeks before coronary bypass surgery. Three-fold increase of serum eicosapentaenoic acid and 20% reduction of triglyceride levels were found preoperatively in the n-3 group, while the two groups were similar as regards monocyte and platelet counts, mean platelet volume and monocyte activation as expressed by thromboplastin activities. For determination of transcardiac gradients, coronary sinus and aortic blood were sampled preoperatively 5, 10 and 30 minutes after release of the aortic cross-clamp. In both patient groups the monocyte count was lower in coronary sinus than in aortic blood at 5 and 10 minutes, but the differences were not significant. The platelet counts showed no significant change. In vitro stimulation of monocytes, however, evoked significantly (p0.05) less thromboplastin activity in coronary sinus blood than in aortic blood at all three sampling times, without significant intergroup difference. The monocytes most sensitive to activation presumably were trapped in the reperfused myocardium, and this sequestration was not hindered by pretreatment with n-3 fatty acids.

Cardiac surgical complications may be caused by a plethora of events. Oxygen free radicals may participate in the pathophysiology of cardiopulmonary bypass and myocardial ischaemia-reperfusion injury. The evidence of free radical production during bypass is limited, and studies of the effect of free radical scavengers even more limited. Experimental work points towards a role of oxygen free radicals in reperfusion damage of the ischaemic myocardium, but clinical data are lacking. Hitherto the clinical availability of free radical scavengers/antioxidants has been scarse. At present more such drugs are becoming clinically applicable, and trials on their effect are highly warranted, in particular as an adjuvant in myocardial protection.

SummaryTwenty patients accepted for coronary bypass surgery were randomized to receive either a concentrated ethylester compound of n-3 fatty acids, with a daily dose of 3.15 g of eicosapentaenoic acid (EPA) and 1.89 g of docosahexaenoic acid (DHA), or corn oil (controls) in a double blind study, to evaluate the effect on lipids, platelets and coagulation during the pre- and postoperative phase.Only patients with fasting triglyceride (TG) levels ≥1.6 mmol/1 at recruitment were eligible. The study was continued for 5 to 6 months. Surgery was usually performed at mid-intervention. Blood samples were collected during morning hours in fasting subjects, just prior to intervention, preoperatively and at final postoperative follow-up. Moreover, blood loss was accurately accounted for postoperatively.A threefold increase (p = 0.0001) of EPA was noted at pre-and postoperative follow-up. TG-levels were reduced 20 and 39%, respectively, in patients on n-3 fatty acids, reaching statistical significance at end of intervention (p = 0.034). TG-levels in controls remained largely unchanged. In patients on n-3 fatty acids, there was a statistically significant increase in serum total cholesterol preoperatively, but this change was no longer present at completion of the study.No significant changes were noted in platelet function, as judged by bleeding time, collagen induced platelet aggregation and release of TxB2 during aggregation. Parameters of extrinsic coagulation, including phospholipase C-sensitive factor VII (PLC-VII) and extrinsic pathway inhibitor (EPI), also remained essentially unchanged in both groups of patients. However, fibrinogen was significantly reduced in controls (p No significant difference in postoperative bleeding was noted between the two groups of patients.

The production of oxygen free radicals (OFR) by leucocytes was evaluated ex vivo by chemiluminescence (CL) before, during and after routine coronary artery bypass surgery (group A, n=11). The possibility of leucocyte trapping in the coronary circulation during the early reperfusion period was also investigated (group B, n=9). In group A, arterial blood samples were taken immediately before the start of surgery during anaesthesia, five minutes before and five and 30 minutes after the start of cardiopulmonary bypass (CPB), five minutes before and five and 30 minutes after the start of reperfusion of the heart, and then four and 24 hours after the end of CPB. In group B, arterial and coronary sinus blood samples were simultaneously drawn five and 30 minutes after the release of the aortic crossclamp. All blood samples were corrected for haemodilution. In group A, both CL and the level of circulating leucocytes declined during CPB. The lowest value of CL was measured 30 minutes after the start of CPB (69± 2% of baseline values) (mean±SEM). The lowest level of leucocytes was found after 30 minutes of CPB: 2.6±0.4 (109/l) vs 4.2±0.5 before surgery. Twenty-four hours after CPB, CL was increased to 170±49% and a leucocytosis was present (12.2±1.1). In group B, after five minutes of reperfusion the number of circulating leucocytes in arterial blood was 3.8±0.9 x 109/l as compared to 2.2±0.5 x 109/l in the coronary sinus (p

Polymorphonuclear granulocytes (PMN) are suggested mediators of myocardial ischemia-reperfusion injury. We have previously shown that activated PMN producing oxygen free radicals (OFR) in the coronary circulation are cardiodepressive. OFR may induce lipid peroxidation and production of eicosanoids. We have investigated the influence of cyclo-oxygenase and lipoxygenase inhibitors on the effects of activated, OFR producing PMN in the Langedorff rat heart model. Left ventricular developed pressure (VLDP) was measured by a balloon in the left ventricle. Human PMN and drugs were given into the aortic cannula for 10 min and the hearts were observed for 30 min thereafter. After infusion for 5 min OFR production in the cellular infusate was measured at the level of the aortic cannula by a chemiluminescence (CL) technique. Phorbol 12-myristate 13-acetate (PMA)-activated PMN ( n = 8), produced a CL response of 27649 ± 11048 counts (mean ± s.e.m. ), and reduced coronary flow (CF) to 53 ± 6% (mean ± s.e.m. ) and LVDP to 38 ± 9% of baseline values at the end of the observation period. Ibuprofen ( n = 6), a cyclooxygenase (CO) inhibitor, neither influenced the CL response (31915 ± 7563) of activated PMN, nor the reduction of CF and LVDP at this time. Although both BW 755C ( n = 7), a dual inhibitor of CO and lipoxygenase (LO) (CF:90 ± 4%, LVDP:99 ± 6%) and diethylcarbamazine (DCM) ( n = 8), a LO inhibitor (CF:88 ± 11%, LVDP:87 ± 4%), significantly inhibited the cardiodepressive effects of activated PMN. BW 755C alone abolished the CL response (431 ± 158 counts), whereas DCM had no effect on CL (30105 ± 1698 counts). In conclusion, the injurious effects of activated leukocytes in the coronary circulation seem to be mediated through LO products.

A role of proteasomal proteolysis in the pathogenesis of ischemia-reperfusion is being actively studied. To evaluate the participation of the proteasome in postconditioning phenomenon, we used primary culture of neonatal cardiomyocytes. 30 minutes of anoxia followed by 60 minutes of reoxygenation was undergone. Postconditioning was modeled by 3 cycles of 1-minute reoxygenation followed by 1-minute anoxia, respectively. Clasto-lactacystin b-lactone, a specific proteasome inhibitor, in the dose that does not cause cell death (2.5 mM) was added to the culture medium just before the cycles of postconditioning. Percentages of living, necrotic, and apoptotic cells were determined by staining with bisBenzimide and propidium iodide. Autophagy was demonstrated by staining vacuolar structures with monodansyl cadaverine. Proteasomal activity was determined by cleavage intensity of specific fluorogenic substrates. Trypsin-like, chymotrypsin-like and peptidyl-glutamyl peptide-hydrolyzing (PGPH) activities were decreased after anoxia. Reoxygenation led to an increase in trypsin-like and chymotrypsin-like activities comparing to anoxia, but these parameters never reached the control levels. PGPH activity was restored up to the initial level. Postconditioning increased numbers of living cells and decreased that of necrotic, apoptotic and autophagic cells. Paradoxically, it was established, that proteasome inhibitors prevented the necrotic and apoptotic cell death of cardiomyocytes in anoxia-reoxygenation, but in the same concentration abolished the effects of postconditioning. The data obtained permit to suppose that proteasome inhibitors can be used for pharmacological postconditioning.

In the paper the data concerning the possibility of the reproduction of the postconditioning phenomena in the cardyomicyte culture are presented. Primary cultures of cardiomyocytes from neonatal rats underwent 30 minutes of anoxia followed by 60 minutes of reoxygenation. Three different models of postconditioning were used: 3 cycles of 1, 3, or 5 minutes of reoxygenation followed by 1, 3, or 5 minutes of anoxia, respectively. The percentage of living, necrotic, and apoptotic cells were determined by staining with Hoechst 33342 and propidium iodide. Autophagy was demonstrated by the staining of vacuolar structures in vivo by monodansyl cadaverine. After anoxia and reoxygenation the amount of living, necrotic and apoptotic cells were 79 +/- 1.5, 7.8 +/- 0.9 and 13 +/- 1.5 %, respectively (in unstimulated cell culture 90 +/- 0.8, 3.3 +/- 0.3, and 5.5 +/- 0.7, P0.0001 for all). Postconditioning with 1 min anoxia 3-fold increased the amount of living cells and decreased the number of necrotic and apoptotic cells (P = 0.002, P = 0.02 and P = 0.043 respectively). Postconditioning with cycles of 3 and 5 minutes had a gradually reduced effect compared to cycles of 1 minute. The percentage of autophagic cells in control cell culture was 4.3 +/- 0.3%. This number increased after anoxia-reoxygenation to 14 +/- 0.8%, and was reduced by postconditioning (P0.001). The data obtained indicate that postconditioning is one of the effective methods of cardioprotection and could effectively decrease the amount of cardiomyocytes with traits of programmed or non-programmed cell death.

We have established a model of adaptation to ischemia by breathing a hyperoxic gas mixture, which may be directly employed in clinical practice. Hyperoxia improves postischemic function and reduces myocardial necrosis in globally and regionally ischemic rat and mouse hearts, protects hearts of animals with severe atherosclerosis, and modulates in vitro reactivity of isolated aortic rings. Hyperoxic preconditioning is most efficient when the inspired oxygen fraction is >80% oxygen, with different exposure times in rats and mice. In rats the protection is both immediate and delayed, while in mice only immediate protection can be evoked. Exposure to hyperoxia causes an oxidative stress evident as increased serum lipid peroxidation products and reduced antioxidant defence. When breathing hyperoxic gas a rapid nuclear translocation of nuclear factor kappa B (NFκB) in the lungs is followed by a cardiac NFκB activation. In conjunction with hyperoxia the mitogen activated protein kinases (MAPK) p38, ERK1/2, and JNK are phosphorylated in the heart. Pharmacological inhibition of NFκB activation abolished the beneficial effects of hyperoxia. During Langendorff-perfusion with induced global ischemia, phosphorylation of MAPK as well as translocation of NFκB is reduced in animals subjected to hyperoxia prior to the experiments, the latter perhaps due to increased formation of the NFκB inhibitor IkBα. A posssible role for the NFκB-regulated gene inducible nitric oxide synthase (iNOS) in the hyperoxia response was investigated in knock out mice, who had no functional or antiinfarct protection of preconditioning by either hyperoxia or classic ischemic preconditioning. However, neither cardiac iNOS nor contents of antioxidants, heat shock protein 70, or endothelial NOS in the heart increased after hyperoxia. Thus, the signal transduction pathways and organ effectors of hyperoxic protection are not fully determined, but appear to involve MAPK and NFκB. Hyperoxia may have a large potential in the pretreatment of patients undergoing not only open heart procedures, but also in front of any major surgery.

The isolated, buffer-perfused heart is probably the most widely used model in experimental heart research, and the coronary effluent is often analysed for markers of myocardial injury. Adsorption to surrounding materials may be a serious problem of protein measurements in solutions with low protein concentrations. The aims of the present study were to investigate the importance of the preanalytical phase when measuring cardiac troponin T (cTnT) in a buffer perfusate and to investigate whether addition of albumin to the effluent might increase recovery of cTnT and improve the assay. Coronary effluent was collected in tubes of different materials and in tubes with 40 g/L bovine albumin, and then frozen. cTnT was analysed at different time points after withdrawal from the freezer. cTnT was 2.3-119 times higher in effluent with albumin. In effluent without albumin, cTnT concentration declined to 2% of the initial concentration after two episodes of freezing and thawing. The cTnT loss could not be prevented by using polystyrene or siliconized glass, but was partially inhibited in effluent with albumin. Furthermore, creatine kinase and lactate dehydrogenase levels were higher in effluent with albumin. The within-series coefficient of variation for cTnT was markedly improved when using effluent with albumin.

Exposure of rats to hyperoxia before organ harvesting protected their isolated hearts against global ischaemia-reperfusion injury in a previous study. The present study investigates whether hyperoxia influences vasomotor function and regional ischaemia of the heart. Isolated rings of the thoracic aorta were obtained from rats immediately or 24 h after in vivo exposure to 60 min of hyperoxia (95% O2), and the in vitro dose-response to phenylephrine (PHE), prostaglandin F2alpha (PGF2alpha) and endothelin-1 (ET-1), acetylcholine (Ach) and sodium nitroprusside (SNP) was assessed. Hyperoxia in vivo increased the relaxation of aortic rings to Ach and SNP, while it delayed contraction to PHE. The effect was more evident when the vessels were harvested immediately rather than 24 h after hyperoxic exposure. In separate experiments rat hearts were isolated immediately after hyperoxia, buffer-perfused, and subjected to 30 min of regional ischaemia and reperfused for 120 min. Infarct size was determined by triphenyl tetrazolium chloride staining. Hyperoxia significantly reduced infarct size. In normoxic controls 23.0 +/- 8.3% of the area at risk was infarcted, while in hyperoxic animals infarct size was 14.8 +/- 5.6% of the area at risk (P = 0.012). Exposure of rats to hyperoxia modifies the vasomotor response of isolated aortic rings, and reduces the infarct size of isolated rat heart. These novel aspects of hyperoxic treatment require further studies to explore the potential of its clinical application.

SummaryTwenty patients with coronary heart disease (CHD) and elevated serum lipids were randomized into 2 groups of 10 to receive encapsulated preparations of either a concentrated ethylester form of eicosapentaenoic acid (EPA) and docosa-hexaenoic acid (DHA) or corn oil in doses of 6 g per day, given double blindly for approximately two months prior to coronary bypass surgery. Lipopolysaccharide (LPS) induced monocyte thromboplastin synthesis was studied during the preoperative period and one week following surgery. The ability of n-3 fatty acids to modify tissue factor pathway inhibitor (TFPI) and tissue plasminogen activator inhibitor (PAI-1) was also evaluated along with fibrinogen and thrombin-antithrombin III (TAT) complexes.No significant changes were noted preoperatively. Monocyte reactivity, PAI-1, fibrinogen and TAT increased significantly after surgery. These changes were not modified by preoperative loading with n-3 fatty acids.

Ventricular fibrillation (VF) and ventricular tachycardia (VT) are common phenomena during reperfusion. In experimental research many hearts have to be excluded from haemodynamic evaluation because of severe arrhythmias. Theoretically, electroconversion or mechanical conversion (MC) might be used to convert VF or VT. MC induces a physical shock analogous to a chest thump. The aim of this study was to investigate the efficacy of MC in isolated, perfused rat hearts, and to see whether MC itself induced myocardial cell injury and functional impairment. Langendorff-perfused rat hearts (n = 89) from several experimental series subjected to 30 min of global ischaemia and 60 min of reperfusion were retrospectively analysed. Left ventricular systolic (LVSP), end-diastolic (LVEDP), and developed (LVDP) pressures, coronary flow (CF), and heart rate (HR) were measured. If VF or VT continued for 1 min during reperfusion, MC was attempted by a flick of the forefinger to the right ventricle. If VF or VT still occurred, MC was repeated. Hearts that did not have regular beating after 20 min of reperfusion were excluded. Release of cardiac troponin T (cTnT) was measured before ischaemia and after 20 min of reperfusion. Forty-four out of 89 hearts had VF or VT during reperfusion. Thirty-five hearts were converted, 18 of which were converted by one or two MCs only. The higher the total number of MCs employed, the more cTnT was released. After 20 min of reperfusion, LVEDP, LVDP and CF were better in hearts with a higher number of MCs and with increased release of cTnT. After 60 min of reperfusion, LVEDP was still improved in hearts with more cTnT release, whereas LVSP was lower, and LVDP and CF were independent of the number of MCs. There was no consistent correlation between release of cTnT and heart dysfunction. In conclusion, MC effectively converted VF or VT. MCs increased post-ischaemic myocardial cell damage, as judged from increased cTnT release. Post-ischaemic dysfunction was partly attenuated in hearts with multiple MCs, and did not correlate with release of cTnT. We feel that MCs should not be used in isolated, perfused hearts.

Objective: To compare the effects of ventilation with intermittent positive pressure and external high frequency oscillation by the Hayek Oscillator during the first 5 h after coronary artery bypass grafting. Methods: Eleven patients were randomized to intermittent positive pressure ventilation throughout the observation period (5 h), while 13 patients were initially ventilated with intermittent positive pressure ventilation, then by external high-frequency oscillations for 4 h, changing to positive pressure ventilation for the last hour. Results: Cardiac index, stroke volume index, right ventricular stroke work index, right ventricular end-diastolic volume index and mixed venous oxygen saturation were significantly increased during ventilation with external high-frequency oscillations, and arteriovenous oxygen content difference was significantly reduced. There were no significant inter- or intragroup differences in fluid accumulation, mean arterial blood pressure, arterial blood gases, pulmonary artery pressure. central venous pressure, pulmonary capillary wedge pressure, heart rate, systemic vascular resistance index, pulmonary vascular resistance index, intrapulmonary shunt fraction, right ventricular ejection fraction, right ventricular end-systolic volume index and left ventricular stroke work index. Conclusions: Ventilation by external high-frequency oscillations increases cardiac index and improves tissue perfusion. The increased pumping of the heart is probably caused by changes of the intracardiac pressure-volume relationship. The Hayek Oscillator may have distinct cardiovascular benefits as ventilatory assistance in postoperative cardiac surgical patients.

The effects of reactive oxygen species (ROS) on myocardial antioxidants and on the activity of oxidative mitochondrial enzymes were investigated in the following groups of isolated, perfused rat hearts. I: After stabilization the hearts freeze clamped in liquid nitrogen ( n = 7). II: Hearts frozen after stabilization and perfusion for 10 min with xanthine oxidase (XO) (25 U/l) and hypoxanthine (HX) (1 mM) as a ROS-producing system ( n = 7). III: Like group II, but recovered for 30 min after perfusion with XO + HX ( n = 9). IV: The hearts were perfused and freeze-clamped as in group III, but without XO + HX ( n = 7). XO + HX reduced left ventricular developed pressure and coronary flow to approximately 50% of the baseline value. Myocardial content of hydrogen peroxide (H 2 O 2 ) and malondialdehyde (MDA) increased at the end of XO + HX perfusion, indicating that generation of ROS and lipid peroxidation occurred. Levels of H 2 O 2 and MDA normalized during recovery. Superoxide dismutase, reduced glutathione and α -tocopherol were all reduced after ROS-induced injury. ROS did not significantly influence the tissue content of coenzyme Q 10 (neither total, oxidized, nor reduced), cytochrome c oxidase, and succinate cytochrome c reductase. The present findings indicate that the reduced contractile function was not correlated to reduced activity of the mitochondrial electron transport chain. ROS depleted the myocardium of antioxidants, leaving the heart more sensitive to the action of oxidative injury. Copyright © 1996 Elsevier Science Inc.

A model of cardiac dysfunction induced by reactive oxygen species (ROS) was established by adding hydrogen peroxide (H2O2) to the perfusate of isolated, Langendorff-perfused rat hearts, and the mechanism of functional injury was investigated. The following groups were included: 1 (n = 7), control perfusion; 2 (n = 11), perfusion with H2O2 (180 mumol 1(-1) for 10 min followed by recovery for 50 min; 3 (n = 4), control perfusion with N-acetylcysteine (NAC, 100 mumol 1(-1); 4 (n = 7), perfusion with H2O2 and NAC; 5 (n = 4), control perfusion with thiourea (15 mmol 1(-1), 6 (n = 7), H2O2 and thiourea together; 7 (n = 4), control perfusion with catalase (150 U ml-1); 8 (n = 7), catalase and H2O2, 9 (n = 4), control perfusion with deferoxamine (5 mmol 1(-1); and 10 (n = 7), deferoxamine and H2O2. coronary flow (CF), left ventricular developed pressure (LVDP), left ventricular end-diastolic pressure (LVEDP), and heart rate (HR) were measured. All values are mean +/- SEM. When given alone, catalase, thiourea, NAC and deferoxamine did not influence left ventricular pressures, but NAC, catalase and thiourea increased CF. H2O2 increased CF (maximum 146 +/- 6% of baseline value after 5 min, p0.001 compared to group 1), decreased LVDP (minimum 14 +/- 5% of baseline value after 10 min, p0.0004), and increased LVEDP (from 0 mmHg to a maximum of 54 +/- 7 mmHg after 5 min recovery, p0.0003). All these changes gradually reversed during recovery. Catalase and thiourea both inhibited the H2O2-induced effects, but catalase inhibition was more complete. Neither NAC nor deferoxamine had any effect on H2O2-induced cardiac dysfunction. In conclusion, H2O2 perfusion is a convenient and reversible model of ROS-induced functional injury to isolated rat hearts. H2O2, rather than the hydroxyl radical, seems to be the main injurious ROS in this model.

Myocardial ischemia-reperfusion injury increases both tissue levels and release of histamine. To study the possible effects of ischemia-reperfusion on histamine metabolism tissue activities of histidine decarboxylase (HDC), histamine N-methyl transferase (HNMT) and diamine oxidase (DAO) were investigated in isolated rat hearts subjected to either 20 min global ischemia and 40 min reperfusion (n = 10) or control perfusion (n = 8). Histamine in the coronary effluent increased from 21 +/- 4 nmol/min (mean +/- SEM) before ischemia to 55 +/- 5 and 50 +/- 7 nmol/min after 4 and 10 min reperfusion (p0.004 and p0.004). Tissue HDC activity did not change during observation in any group. HNMT activity was unchanged in controls, but increased from 0.37 +/- 0.04 to 0.84 +/- 0.18 and 0.96 +/- 0.22 pmol methylhistamine/mg protein hour after 4 and 10 min reperfusion (p0.008 and p0.01). DAO decreased similarly in controls and ischemic-reperfused hearts during observation. In conclusion, the previously observed increase of tissue histamine during reperfusion cannot be explained by increased histamine synthesis or decreased histamine catabolism.

Leukocytes can take part in an inflammatory response in the heart after myocardial infarction or cardio-thoracic surgery. To investigate the injurious mechanism of activated polymorphonuclear leukocytes (PMN), isolated rat hearts were perfused with phorbol 12-myristate 13-acetate (PMA) activated PMN (3 x 10(6)/ml) alone for 10 min, in combination with a mixture of oxygen free radical scavengers (superoxide dismutase+catalase+thiourea) or in combination with ibuprofen (IBU), a cyclooxygenase inhibitor or diethylcarbamazine (DCM), a lipoxygenase inhibitor or BW 755C, a dual inhibitor of cyclooxygenase and lipoxygenase and an oxygen free radical scavenger. After 30 min of recovery, the hearts were perfusion-fixed with glutaraldehyde for electron microscopical examination. Based on examination of 25 micrographs per heart obtained by a random sampling procedure and on morphometric methods, volume fractions (Vv) of mitochondria (mito), altered mitochondria (alt mito), myofilament, and cellular edema were measured as fractions of myocyte volume. The most important finding was that Vv(alt mito/myocyte) was 0.09 +/- 0.16 and 0.02 +/- 0.04 in the hearts receiving PMN+PMA alone and when scavengers were added, respectively, whilst no changes in mitochondrial ultrastructure was observed after addition of IBU, BW 755C or DCM. Vv(mito/myocyte) was for PMN+PMA alone: 0.33 +/- 0.04, +scavengers: 0.29 +/- 0.02 +IBU:0.29 +/- 0.02, +BW 755C: 0.23 +/- 0.03*, +DCM: 0.28 +/- 0.02 (mean +/- S.D., *P0.05 compared to PMN+PMA). Capillary wall volume (cap wall) as a fraction of the whole capillary was also quantified. Vv(cap wall/cap) was for PMN+PMA alone: 0.26 +/- 0.06, +scavengers: 0.22 +/- 0.03, +IBU: 0.19 +/- 0.04*, +BW755C: 0.21 +/- 0.03, +DCM: 0.15 +/- 0.04* (*P0.05). These results further strengthen the notion that activated PMN are intravascularly active. In addition to exerting a cardiodepressive effect the present study shows that activated PMN can induce structural changes in the heart through the combined action of oxygen free radicals and arachidonic acid metabolites.

Histamine has inotropic, chronotropic, arrhythmogenic, and vasoactive effects, and is released from the heart in ischaemia-reperfusion injury. The effect of ventricular fibrillation (VF) and defibrillation (DEF) on histamine release was investigated in 9 anaesthetized patients undergoing transvenous implantation of ICD. Concomitant arterial and coronary sinus (CS) blood samples were drawn before induction of VF (duration 20 seconds), immediately after, and 2 and 5 min after DEF (18-24 Joules). Basal arterial histamine was 2.5 +/- 6 nmol/l, and did not increase after VF. The histamine level in CS was 1.1 +/- 0.2 nmol/l before VF (p0.008 compared to arterial), and increased to 2.5 +/- 0.6 nmol/l immediately after (p0.045 compared to basal), to 3 +/- 1.1 nmol/l 2 min after (p0.45), and to 2.4 +/- 0.8 nmol/l 5 min after VF. In the basal state there was an uptake of histamine across the coronary circulation. After VF/DEF the level of histamine increased in coronary venous blood, suggesting cardiac release of histamine.

Weekly treatments with doxorubicin encapsulated in long circulating, sterically stabilised liposomes (DOX-SL) reduced the incidence of metastases from primary mammary carcinoma from 24 of 47 untreated mice to 3 of 23 treated mice. Toxic side-effects were limited to minor, transient weight losses.

Histamine is released from the heart during ischaemia-reperfusion injury. As histamine has cardiac effects, we investigated the role of histamine in ischaemia-reperfusion injury of isolated rat hearts. A Langendorff-model with 30 min global (37 degrees C) ischaemia followed by 60 min reperfusion was employed. The effects of ischaemia alone (n = 10, group 1.1 + n = 10, group 2.1, 2 different series), and ischaemia with H1- and H2-receptor blockade with cimetidine (10 microM, n = 10), chlorpheniramine (10 microM, n = 8), terfenadine (10 microM, n = 8), and promethazin (10 microM, n = 9), or both cimetidine and chlorpheniramine (n = 8), were studied. Histamine was measured in the coronary effluent and cardiac tissue of group 1.1. Release of histamine increased from 6.5 +/- 1 pmol min-1 before ischaemia to 19 +/- 3 pmol min-1 at the start of reperfusion. Ischaemia decreased left ventricular developed pressure to 18 +/- 11% (1.1) and 50 +/- 11% (2.1) of initial value (mean +/- SEM) at the start of reperfusion. Left ventricular end-diastolic pressure increased from 0 to 79 +/- 8 mmHg (1.1) and 39 +/- 9 (2.1) mmHg, while left ventricular systolic pressure was unchanged (101 +/- 12% in 1.1 and 101 +/- 10% in 2.1). Severe arrhythmias were induced in 90 (1.1) and 30 (2.1)% of the hearts, while coronary flow decreased during reperfusion. H2-blockade did not modify the changes in left ventricular pressures, coronary flow, or heart rate induced by ischaemia. Three different H1-blockers increased left ventricular systolic pressure, inhibited the decrease of developed pressure, attenuated the increase of end-diastolic pressure, and totally inhibited reperfusion arrhythmias. The effect of both blockers together was similar to that of H1-blockers alone. Coronary flow was increased during reperfusion in two of the groups with H1-blocker compared with ischaemic controls. Increased release of histamine from ischaemic-reperfused rat hearts concurred with depression of left ventricular function and arrhythmias during early reperfusion. Cardiac dysfunction during reperfusion was attenuated by three different H1-receptor blockers.

Production of oxygen free radicals and subsequent lipid peroxidation are thought to occur during cardiopulmonary bypass (CPB) and myocardial ischaemia- reperfusion injury. Malondialdehyde (MDA), a lipid peroxidation product, was measured simultaneously in arterial and coronary sinus blood before CPB and after release of the aortic crossclamp. Additional arterial samples were drawn pre-, per-, and postoperatively. Thirteen patients scheduled for coronary artery and/or valvular surgery were studied. Cold, crystalloid, cardioplegic arrest (54 [35-120] minutes, median [range]) was induced retrogradely. Preoperatively, arterial MDA was 0.78 ± 0.4 (mean ± SD) μmol/l, and increased during CPB (highest level 3.66 ± 1.08 μmol/l, p < 0.002, 30 minutes after the start of reperfusion). Arterial MDA was still increased four hours after the end of CPB (3.17 ± 0.88 μmol/l, p < 0.003), but had returned to normal the first postoperative day. No difference was found between arterial and coronary sinus samples at any time. In conclusion, MDA increased in arterial blood during CPB, indicating that lipid peroxidation occurred. There was no intracoronary release of MDA during reperfusion of the ischaemic heart.

Twenty patients with coronary heart disease (CHD) and elevated serum lipids were randomized into 2 groups of 10 to receive encapsulated preparations of either a concentrated ethylester form of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) or corn oil in doses of 6 g per day, given double blindly for approximately two months prior to coronary bypass surgery. Lipopolysaccharide (LPS) induced monocyte thromboplastin synthesis was studied during the preoperative period and one week following surgery. The ability of n-3 fatty acids to modify tissue factor pathway inhibitor (TFPI) and tissue plasminogen activator inhibitor (PAI-1) was also evaluated along with fibrinogen and thrombin-antithrombin III (TAT) complexes. No significant changes were noted preoperatively. Monocyte reactivity, PAI-1, fibrinogen and TAT increased significantly after surgery. These changes were not modified by preoperative loading with n-3 fatty acids.

Release of histamine (H) by ischemia-reperfusion injury was investigated in isolated rat hearts (Langendorff model). The effect of 10, 15, 20, 25, 30, 40 and 60 min ischemia (n = 10 each) on H in the coronary effluent and in cardiac tissue was studied after 4 min reperfusion. Release of creatine kinase and lactate dehydrogenase in the coronary effluent increased with time of ischemia. Tissue H increased from 95 +/- 10 ng/g rat heart (mean +/- SEM) before ischemia to max 148 +/- 10 ng/g after 20 min ischemia (p0.002), and increased also after 15 (p0.01), 25 (p0.01), and 30 min (p0.045). H in the coronary effluent increased after 15 (from 16 +/- 3 to 26 +/- 2 pmol/min, p0.044), 30 (26 +/- 6 pmol/min, p0.027), and 60 min ischemia (47 +/- 6 pmol/min, p0.0044). Release of H during ischemia-reperfusion is neither dependent on the severity of the ischemic insult, nor on the level of tissue H.

Secretion of immunoreactive atrial natriuretic factors (ANF) after injury by ischaemia-reperfusion and toxic oxygen metabolites (TOM) was investigated in the following groups of Langendorff-perfused rat hearts: 1.1., control perfusion; 1.2., hearts perfused with H2O2 (200 mumol l-1) as a TOM-generating agent for 10 min, followed by recovery for 30 min; 1.3., thiourea (10 mmol l-1), a hydroxyl radical scavenger, was given together with H2O2; 2.1., control perfusion; 2.2., ischaemia (37 degrees C) for 20 min followed by reperfusion for 40 min. Ischaemia-reperfusion and TOM temporarily decreased left ventricular developed pressure and increased left ventricular end-diastolic pressure. The cardiac effects of H2O2 were inhibited by thiourea. Coronary flow (CF) was increased by TOM and decreased by ischaemia-reperfusion. Immunoreactive ANF was measured sequentially in the coronary effluent by radioimmunoassay. Basal secretion of immunoreactive ANF for all groups pooled was 0.45 +/- 0.02 pmol min-1 (mean +/- SEM), and did not change significantly with time in any group. In conclusion, ischaemia-reperfusion and TOM do not influence secretion of immunoreactive ANF.

Histamine is synthetized in the heart, and released by ischemia-reperfusion injury in several species. Histamine has arrhythmogenic, chronotropic, inotropic and vasoactive effects. Cardiac histamine release during ischemia-reperfusion may be mediated by toxic oxygen metabolites. We studied the effect of ischemia-reperfusion and toxic oxygen metabolites on release and synthesis of histamine in the isolated rat heart (Langendorff model). The following groups were included: I, (n = 10) control perfusion for 60 min; II, (n = 7) H2O2 (200 microM) was given for 10 min followed by 50 min recovery; III, (n = 7) thiourea (15 mM) was given in addition to H2O2; IV, (n = 7) thiourea given alone; V, (n = 7) catalase (150 U/ml) plus H2O2; VI, (n = 7) 20 min ischemia followed by 40 min reperfusion. The contents of histamine in the coronary effluent and in cardiac tissue were measured repeatedly (radioenzymatic method). Ischemia-reperfusion and toxic oxygen metabolites increased release of histamine in the coronary effluent. Concomitantly the histamine contents in cardiac tissue increased, indicating increased synthesis of histamine.

The metabolic function of the lungs may be impaired in acute lung injuries. The present work examined the effect of toxic oxygen metabolites (TOM) on the pulmonary clearance of prostaglandin E2 (PGE2). Isolated rat lungs perfused with plasma were exposed to TOM, generated by xanthine oxidase (XO) and hypoxanthine (HX) in the perfusate. Inactivation of PGE2 was determined by superfusion bioassay technique. XO and HX (n = 6) reduced the inactivation of PGE2 from 78 +/- 4% (mean +/- SE) to 61 +/- 3%. This reduction was inhibited by the free radical scavengers superoxide dismutase and catalase, as well as by allopurinol, an inhibitor of XO. Neither hydrostatic lung edema nor perfusion per se decreased the inactivation of PGE2. Lungs pretreated with indomethacin still showed impaired PGE2 inactivation after exposure to XO and HX, indicating that a possible release of PGE2-like substances did not influence our findings. This study indicates that TOM may impair pulmonary metabolic function as shown by reduced inactivation of PGE2.

Twenty patients accepted for coronary bypass surgery were randomized to receive either a concentrated ethylester compound of n-3 fatty acids, with a daily dose of 3.15 g of eicosapentaenoic acid (EPA) and 1.89 g of docosahexaenoic acid (DHA), or corn oil (controls) in a double blind study, to evaluate the effect on lipids, platelets and coagulation during the pre- and postoperative phase. Only patients with fasting triglyceride (TG) levels greater than or equal to 1.6 mmol/l at recruitment were eligible. The study was continued for 5 to 6 months. Surgery was usually performed at mid-intervention. Blood samples were collected during morning hours in fasting subjects, just prior to intervention, preoperatively and at final postoperative follow-up. Moreover, blood loss was accurately accounted for postoperatively. A threefold increase (p = 0.0001) of EPA was noted at pre- and postoperative follow-up. TG-levels were reduced 20 and 39%, respectively, in patients on n-3 fatty acids, reaching statistical significance at end of intervention (p = 0.034). TG-levels in controls remained largely unchanged. In patients on n-3 fatty acids, there was a statistically significant increase in serum total cholesterol preoperatively, but this change was no longer present at completion of the study. No significant changes were noted in platelet function, as judged by bleeding time, collagen induced platelet aggregation and release of TxB2 during aggregation. Parameters of extrinsic coagulation, including phospholipase C-sensitive factor VII (PLC-VII) and extrinsic pathway inhibitor (EPI), also remained essentially unchanged in both groups of patients. However, fibrinogen was significantly reduced in controls (p less than 0.05) at end of intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

A 30-year-old man presented with threatened rupture of an infrarenal aortic aneurysm. Clinical and laboratory investigations revealed no traumatic, atherosclerotic, infectious or inflammatory cause. Histologic examination of the aortic wall showed cystic degeneration of the media. Consequently the case could be classified as congenital abdominal aortic aneurysm in an adult.

Inhibitors of the arachidonic acid metabolism (AA) as well as scavengers of oxygen free radicals (OFR) have been shown to reduce myocardial infarct size. We investigated the effects of two inhibitors of AA metabolism on the cardiac effects of OFR. Isolated rat hearts were retrogradely perfused for 10 min with buffer containing hypoxanthine (HX, 1 mmol l-1) and xanthine oxidase (XOD: 24 U l-1) alone (n = 11), or with the addition of ibuprofen (IBU) (n = 6) (a cyclooxygenase inhibitor) or BW 755C (n = 6) (a dual inhibitor of cyclo-oxygenase and lipoxygenase). The hearts were observed for 30 min thereafter (total observation time 40 min). Left-ventricular pressures were measured by a balloon in the left ventricle. HX + XOD significantly reduced left-ventricular developed pressure (LVDP) and coronary flow (CF), but not heart rate. The reduction of LVDP and CF was not significantly ameliorated by the addition of IBU (7.6 x 10(-4) mol l-1) or BW 755C (2 x 10(-3) mmol l-1). OFR increased left-ventricular end-diastolic pressure (LVEDP) from (mean +/- SEM) 0 to 22 +/- 4 mmHg (10 min) and 30 +/- 5 mmHg (40 min). Upon addition of IBU, LVEDP increased from 0 to 24 +/- 8 mmHg and 17 +/- 6 mmHg at 10 and 40 min respectively. The addition of BW 755C almost completely inhibited the increase in LVEDP (1 +/- 1 mmHg and 3 +/- 3 mmHg at 10 min and 40 min). In conclusion, except for inhibition of OFR-induced diastolic dysfunction by BW 755C, neither BW 755C nor IBU appear to inhibit cardiac injury induced by OFR.

Extracorporeal membrane oxygenation was introduced as a supplement ot mechanical ventilation in the treatment of two patients with severe acute respiratory failure and as heart assist in one patient with acute refractory cardiac failure after open heart surgery. The system includes a membrane oxygenator and a roller pump. The whole circuit is coated with partially degraded heparin covalently bound to the surface (Carmeda Bioactive Surface), reducing the need of systemic heparinization to a minimum. In the first case of acute respiratory failure a veno-venous bypass was employed, with cannulas in the right atrium and the femoral vein. Given a blood flow through the circuit of 2.5 l/min, ventilator settings could be favourably reduced. The patient was weaned off the bypass system after six days, off the ventilator after 120 days, and recovered completely. In two cases the system served as partial venoarterial bypass, and blood was returned to the ascending aorta. A 31 year-old male victim of a smoke inhalation lung injury was on bypass for four and a half days. He recovered completely after another 17 days of mechanical ventilation. A 68 year-old man with pump failure after cardiac surgery needed extracorporeal support as heart assist for seven days. On the eighth day he was weaned off intra-aortic balloon-pumping as well. Unfortunately, he died of septicemia, with multiple organ failure, 13 days later. The heparin-coated extracorporeal membrane oxygenation system may represent a major advancement in the treatment of critically ill patients in need of cardiopulmonary assist.

Effects of toxic oxygen metabolites (TOM) on the pulmonary vascular bed and airways were studied in isolated, plasma-perfused rat lungs. TOM were generated by xanthine oxidase (XO) (0. 1 or 0. 25 unit– ml-1) and hyopxanthine (HX) (1 mol. l-1). In vitro measurements by chemiluminescence indicated that the major oxygen metabolite generated by XO and HX was H2O2. Measurements of Po2 in the perfusate as an indicator of O2–consumption suggested that production of TOM by XO and HX was finished, within 30 min. XO and HX induced an early dose-dependent bronchoconstriction and a late increase in transpulmonary pressure (Ptp). Pulmonary arterial pressure (Ppa) increased gradually and levelled off within 30 min with low-dose XO, but not with high-dose XO. As judged by weight increase of the lungs, interstitial edema occurred regularly. Allopurinol, an inhibitor of XO, blocked the lung responses caused by XO and HX. Catalase attenuated all lung responses induced by XO and HX, while superoxide dismutase had no effect. The hydroxyl radical scavenger dimethylsulfoxide abolished the increase in Ptp and attenuated the increase in Ppa, but did not consistently protect the lungs from edema development. This study shows that TOM induce vasoconstriction, bronchoconstriction and lung edema in plasma-perfused rat lungs, mainly due to generation of H2O2 and the hydroxyl radical.

The mitochondrial isoenzyme of aspartate aminotransferase showed only slight increases in serum of twentyseven patients after uncomplicated coronary bypass surgery, which contrasted the rapid and substantial increases in creatine kinase MB. In seven patients suffering perioperative infarction or serious complications, substantial increases in mitochondrial aspartate aminotransferase were detected and the elevations in creatine kinase MB were prolonged. Mitochondrial aspartate aminotransferase may appear as a specific marker of myocardial necrosis following coronary bypass surgery. The elevations of creatine kinase and creatine kinase MB were detected as early as 5 minutes after onset of coronary reperfusion and slightly higher activities were measured in coronary sinus blood than in systemic blood sampled simultaneously. Increases in mitochondrial aspartate aminotransferase, however, could first be measured 8 hours after reperfusion.