Isolated Heart Perfusion Model Research Articles

Myocardial Protective Effect of Xuebijing Injection on Extracorporeal Membrane Oxygenation Perfused Isolated Langendorff Heart Based on the PI3K/AKT Pathway

Objective: This study aimed to investigate the myocardial protective effect of Xuebijing injection in a model of extracorporeal membrane oxygenation (ECMO) isolated heart perfusion and determine the role of the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway. Methods: To establish an ECMO isolated heart perfusion model, Guangxi Bama miniature pigs were randomly divided into two groups: (1) a normal saline group (NS group), in which 50 mL of normal saline was added to the perfusion solution; and (2) a Xuebijing injection group (XBJI group), in which 10 mL of XBJI was added to the perfusion solution and then continuously pumped at 5 mL/h. Perfusion was maintained for 8 h. The hemodynamic changes, inflammatory response, and myocardial enzyme levels at T0, T2, T4, T6, and T8 were evaluated. The protein expression level of the PI3K/AKT pathway was analyzed by Western blot analysis and Reverse Transcription Quantitative Polymerase Chain Reaction (RT-qPCR). Hematoxylin and eosin staining and transmission electron microscopy were used to observe the pathological morphology and ultrastructure of T8 cardiomyopathy. Results: There was no significant difference in hemodynamics between the two groups. XBJI could reduce serum inflammatory factors and myocardial enzyme levels. XBJI also upregulated the expression of PI3K and AKT mRNA and the phosphorylation levels of PI3K and AKT proteins. The results of pathological and electron microscopy showed that XBJI effectively reduced myocardial cell and mitochondrial damage. Conclusion: XBJI can reduce myocardial inflammation and myocardial cell and mitochondrial damage in isolated heart perfusion. XBJI may play a role in the myocardial protection of ECMO isolated heart perfusion by activating the PI3K/AKT pathway.

History of the development of isolated heart perfusion experimental model and its pioneering role in understanding heart physiology.

The isolated heart perfusion model, a fundamental tool in cardiovascular research, has evolved significantly since its inception in the late 19th century. This review traces the development of the isolated heart model, from its early adaptations by pioneers such as Langendorff and Starling to modern advancements by researchers like Morgan and Neely. We discuss the various applications of the model in pharmacological testing, disease modeling, and educational settings, emphasizing its crucial role in understanding cardiac function and disease mechanisms. Recent technological enhancements, including high-resolution imaging, integration with bioengineering, and advanced genomic and proteomic analyses, have significantly broadened the capabilities of these models. Looking forward, we explore potential future developments such as the integration of precision medicine, stem cell research, and artificial intelligence, which promise to revolutionize the use of isolated heart perfusion models. This review highlights the model's crucial role in bridging experimental research and clinical applications.

Entecavir competitively inhibits deoxyguanosine and deoxyadenosine phosphorylation in isolated mitochondria and the perfused rat heart

Deoxyguanosine kinase (dGK) is reported responsible for the phosphorylation of deoxyadenosine (dA) and deoxyguanosine (dG) in the mitochondrial purine salvage pathway. Antiviral nucleoside analogs known as nucleoside reverse transcriptase inhibitors (NRTIs) must be phosphorylated by host enzymes for the analog to become active. We address the possibility that NRTI purine analogs may be competitive inhibitors of dGK. From a group of such analogs, we demonstrate that entecavir (ETV) competitively inhibited the phosphorylation of dG and dA in rat mitochondria. Mitochondria from the brain, heart, kidney, and liver showed a marked preference for phosphorylation of dG over dA (10–30-fold) and ETV over dA (2.5–4-fold). We found that ETV inhibited the phosphorylation of dG with an IC50 of 15.3 ± 2.2 μM and that ETV and dG were both potent inhibitors of dA phosphorylation with IC50s of 0.034 ± 0.007 and 0.028 ± 0.006 μM, respectively. In addition, the phosphorylation of dG and ETV followed Michaelis–Menten kinetics and each competitively inhibited the phosphorylation of the other. We observed that the kinetics of dA phosphorylation were strikingly different from those of dG phosphorylation, with an exponentially lower affinity for dGK and no effect of dA on dG or ETV phosphorylation. Finally, in an isolated heart perfusion model, we demonstrated that dG, dA, and ETV were phosphorylated and dG phosphorylation was inhibited by ETV. Taken together, these data demonstrate that dGK is inhibited by ETV and that the primary role of dGK is in the phosphorylation of dG rather than dA.

Acanthopanax senticosus Protects Against Myocardial Ischemia Reperfusion Injury in Rats

The protective effects of Acanthopanax senticosus on myocardial ischemia reperfusion injury in rats was explored. A total of 60 male Sprague Dawley rats were randomly divided into the sham operated group (group C), the ischemia reperfusion group (group IR), the Acanthopanax senticosus plus blocker group (group ASS+Z), and the Acanthopanax senticosus group (group ASS). The rat myocardial ischemia reperfusion injury models were established through ligating left anterior descending branches of coronary artery in rats. TUNEL assay and Western Blot was used to detect the apoptotic index of myocardial cells and the expression levels of extracellular regulating kinase 1/2 (ERK1/2) and phosphorylation ERK1/2 (p-ERK1/2). Meanwhile, a total of 30 rats were randomly selected and divided into 5 groups; the control group (group c) was the simple ischemia reperfusion group, while groups P1, P2, P3, and P4 were given different dosage concentrations of Acanthopanax senticosus for pre-adaptation. The Langendorff isolated heart perfusion model was used to record the dynamic changes in cardiac functions and coronary artery flow in each group. The results have shown that the Acanthopanax senticosus had certain protective effects on the ischemia reperfusion injury of rat myocardium, as well as the pre-adaptive effects on the systolic functions of left ventricles after reperfusion, which would increase coronary flow and resist the arrhythmia, thereby reducing the apoptosis rates of myocardial cells and protecting the myocardium through activating the ERK1/2 pathway.

Paclitaxel enhances the protective effect of myocardial ischemia preconditioning on ischemia/reperfusion injury in aged rat

Objective: To investigate if paclitaxel can enhance the protective effect of myocardial ischemia preconditioning on ischemia/reperfusion injury in aged ratand explore related mechanism. Methods: Primary cardiomyocytes of Sprague-Dawley rats were isolated by trypsin and divided into 5 groups(n=6 each): control group, hypoxia injury group, hypoxia preconditioning group, paclitaxel group,and paclitaxel+hypoxia preconditioning group. The structure of microtubules and the expression of hypoxia-inducible factor-1α(HIF-1α) were analyzed by immunofluorescence staining. The Langendorff isolated heart perfusion model was applied in 4 groups: hypoxia reperfusion injury group, hypoxia preconditioning group, paclitaxel group, and paclitaxel+hypoxia preconditioning group. Each group was further divided into elderly subgroup and adult subgroup (n=6 each). Left ventricular developed pressure and maximum rate of rise in left ventricular pressure were analyzed. Results: (1) Primary cardiomyocyte experiments showed that the myocardial tubular microtubule structure in control group was intact and evenly stained; most of the microtubules in the hypoxia-injured group were absent and the tubular tissue was broken; the hypoxia-induced damage on microtubule structure was smaller in the hypoxic preconditioning group compared with the hypoxic injury group (microtubule staining was not uniform, and the lattice structure was broken, but not that obvious as in the hypoxia group); the tubular structure of the microtubules of the paclitaxel group was basically complete, and the staining was basically uniform.The integrity of tubular structure was maintained to some extent, similar to a normal microtubule structure in paclitaxel+hypoxia preconditioning group. The expression of HIF-1α in the cytoplasm and nucleus was very low in the control group, which was evidenced in both cytoplasm and nucleus in the hypoxic injury group.The expression was further increased in hypoxic preconditioning group, significant nuclear HIF-1 expression was found in the paclitaxel group, the expression was aggregated in the nucleus in the Paclitaxel+ hypoxia preconditioning group. (2)In Langendorff isolated heart perfusion model, left ventricular developed pressure was similar between the elderly subgroup and the adult subgroup at the end of the infusion,after precondition, 5 minutes of reperfusion, 30 minutes of reperfusion, and 60 minutes of reperfusion in the hypoxic injury group (all P> 0.05).In the hypoxic injury group, both the elderly subgroup and the adult subgroup had lower left ventricular developed pressure at 30 minutes of reperfusion when compared with the end of the infusion((15.63±4.88) mmHg (1 mmHg=0.133 kPa) vs. (95.63±22.14)mmHg and (17.31±2.75)mmHg vs. (91.00±9.58)mmHg, respectively,all P<0.05). In the hypoxic preconditioning group, the adult subgroup had higher left ventricular developed pressure at 5 and 30 minutes of reperfusion when compared with the elderly subgroup((7.13±1.02) mmHg vs. (3.75±1.06)mmHg and (43.94±3.21)mmHg vs.(16.31±1.54)mmHg, respectively,all P<0.01). In the paclitaxel group, the adult subgroup had higher left ventricular developed pressure at 30 and 60 minutes of reperfusion when compared with the elderly subgroup((44.31±7.59)mmHg vs. (5.44±1.21)mmHg, (51.56±6.03)mmHg vs. (22.19±5.14)mmHg, respectively, all P<0.01). In the paclitaxel+hypoxia preconditioning group, both the elderly subgroup and the adult subgroup had lower left ventricular developed pressure at 30 minutes of reperfusion when compared with the end of the infusion((18.63±4.30)mmHg vs. (99.94±8.23) mmHg, P<0.01; (49.69±5.34)mmHg vs. (95.31±5.26)mmHg, P<0.05). Meanwhile, the adult subgroup had higher left ventricular developed pressure at 30 minutes of reperfusion when compared with the elderly subgroup((49.69±5.34)mmHg vs. (18.63±4.33)mmHg, P<0.01).The adult subgroup had higher change rate of maximum rate of rise in left ventricular pressure at 60 minutes of reperfusion when compared with the elderly subgroup in hypoxia preconditioning group, paclitaxel group, and paclitaxel combined hypoxia preconditioning group((62.83±3.92)% vs. (33.33±3.20)%, (44.17±2.32)% vs. (36.67±2.88)%, (72.50±2.66)% vs. (53.17±2.56)%, respectively,all P<0.01). Conclusion: Paclitaxel can enhance the myocardial protective effect of myocardial ischemia preconditioning through stabilizing microtubules of cardiomyocytes and promoting HIF-1α localization in the nucleus.

The effect of epinephrine on reversing bupivacaine-induced asystole in isolated rat heart

Objective To study the influence of epinephrine on reversing bupivacaine-induced asystole in isolated rat heart. Methods Twenty-four adult male SD rats were randomly divided into four groups according to the table of random number(n=6): group B40, EB40, B50 and EB50. Langendorff isolated heart perfusion model was used. Continuous infusion with 100 μmol/L bupivacaine until asystole had been induced for 3 min, then the model was completed. Group B40, perfused with K-H solution containing 40 μmol/L bupivacaine for 20 min. Group EB40, perfused with K-H solution containing 0.15 mg/L epinephrine and 40 μmol/L bupivacaine for 20 min. Group B50, perfused with K-H solution containing 50 μmol/L bupivacaine for 20 min. Group EB50, perfused with K-H solution containing 0.15 mg/L epinephrine and 50 μmol/L bupivacaine for 10 min, then epinephrine was increased to 0.3 mg/L for 10 min. The situation of recovery of heart beat was recorded and the following cardiac functional parameters were monitored during 20 min perfusion: HR, heart rate-pressure product (RPP) and coronary flow (CF). Results The recovery rate of heart beat(100%) in the group EB40 was higher than which in other groups(0)(P<0.01). The recovery time of heart beat in the group EB40 was (35±9) s and the asystole time after recovery of heart beat was (568±182) s. The CF in the groups EB40 and EB50 were higher compared with the groups B40 and B50 (P<0.01). Conclusions The ability of epinephrine on reversing asystole induced by bupivacaine in isolated rat heart is related to the concentration of bupivacaine. When drug concentration of bupivacaine was 40-50 μmol/L, the ability of epinephrine could not be displayed. Key words: Epinephrine; Bupivacaine; Asystole; Resuscitation

Measurement of the efficacy of 2% lipid in reversing bupivacaine- induced asystole in isolated rat hearts.

BackgroundThe reversal efficacy of 2% lipid emulsion in cardiac asystole induced by different concentrations of bupivacaine is poorly defined and needs to be determined.MethodsForty-two male Sprague–Dawley rats were randomly divided into seven groups: B40, B60, B80, B100, B120, B140 and B160, n = 6. The Langendorff isolated heart perfusion model was used, which consisted of a balanced perfusion with Krebs-Henseleit solution for 25 minutes and a continuous infusion of 100 μmol/L bupivacaine until asystole had been induced for 3 minutes. The hearts in the seven groups were perfused with Krebs-Henseleit solution containing a 2% lipid emulsion, and 40, 60, 80, 100, 120, 140 or 160 μmol/L bupivacaine, respectively. Cardiac recovery was defined as a spontaneous and regular rhythm with a rate-pressure product > 10% of the baseline value for more than 1 minute. Our primary outcome was the rate-pressure product 25 minutes after cardiac recovery. Other cardiac function parameters were also recorded.ResultsAll groups demonstrated cardiac recovery. During the recovery phase, heart rate, rate-pressure product, the maximum left ventricular pressure rise and decline in heart rate in the B120-B160 groups was significantly lower than those in the B40-B80 groups (P < 0.05). The concentration of bupivacaine and the reversal effects of a 2% lipid emulsion showed a typical transoid S-shaped curve, R2 = 0.9983, IC50 value was 102.5 μmol/L (95% CI: 92.44 - 113.6).ConclusionsThere is a concentration-response relationship between the concentrations of bupivacaine and the reversal effects of 2% lipid emulsion.

Activation of EGFR/ERBB2 via Pathways Involving ERK1/2, P38 MAPK, AKT and FOXO Enhances Recovery of Diabetic Hearts from Ischemia-Reperfusion Injury

This study characterized the effects of diabetes and/or ischemia on epidermal growth factor receptor, EGFR, and/or erbB2 signaling pathways on cardiac function. Isolated heart perfusion model of global ischemia was used to study the effect of chronic inhibition or acute activation of EGFR/erbB2 signaling on cardiac function in a rat model of type-1 diabetes. Induction of diabetes with streptozotocin impaired recovery of cardiac function (cardiac contractility and hemodynamics) following 40 minutes of global ischemia in isolated hearts. Chronic treatment with AG825 or AG1478, selective inhibitors of erbB2 and EGFR respectively, did not affect hyperglycemia but led to an exacerbation whereas acute administration of the EGFR ligand, epidermal growth factor (EGF), led to an improvement in cardiac recovery in diabetic hearts. Diabetes led to attenuated dimerization and phosphorylation of cardiac erbB2 and EGFR receptors that was associated with reduced signaling via extracellular-signal-regulated kinase 1/2 (ERK1/2), p38 mitogen activated protein (MAP) kinase and AKT (protein kinase B). Ischemia was also associated with reduced cardiac signaling via these molecules whereas EGF-treatment opposed diabetes and/or ischemia induced changes in ERK1/2, p38 MAP kinase, and AKT-FOXO signaling. Losartan treatment improved cardiac function in diabetes but also impaired EGFR phosphorylation in diabetic heart. Co-administration of EGF rescued Losartan-mediated reduction in EGFR phosphorylation and significantly improved cardiac recovery more than with either agent alone. EGFR/erbB2 signaling is an important cardiac survival pathway whose activation, particularly in diabetes, ischemia or following treatment with drugs that inhibit this cascade, significantly improves cardiac function. These findings may have clinical relevance particularly in the treatment of diabetes-induced cardiac dysfunction.

J013 Inhibition of mTOR survival pathway by an embryonic developmental Wnt pathway suppresses preconditioning induced cardioprotection

Ischemic preconditioning (IPC) protects against heart prolonged lethal ischemia by activating a cardioprotective signalling cascade involving Akt and GSK3β; however molecular pathways are still incompletely known. In an in vivo model of IPC, we previously demonstrated that the Wnt pathway can inhibit cardioprotection via a direct target, GSK3β. Here we go further in the preconditioning pathway comprehension. On a retrograde isolated heart perfusion model, two models of preconditioning were set up: IPC via four sequences of 5 min 0 flow ischemia followed by 5 min reperfusion ; a Pharmacological Preconditioning (PCP), by 25 min perfusion of diazoxide, a direct activator of mitoKATP. Preconditioning signalling was studied by Western blot analysis, in hearts harvested just after preconditioning, and cardioprotection was analyzed after 40 min 0 flow ischemia followed by 120 min reperfusion, by TTC staining. We verified that PCP, like IPC, induce an inhibition/phosphorylation of GSK3β (ser9) by activation of Akt (ser479). These results were correlated with a significant reduction of infarct size after ischemiareperfusion (10,8 % and 18 % (n=6, p<0.05) of risk area, after PCP and IPC respectively, vs 37,5 % (n=7, p<0.05) in non preconditioned control hearts). We showed then that both IPC and PCP were able to induce the mTOR survival pathway by increasing P-mTOR (ser2448) and its subcellular targets P70S6K (thr389) and 4E-BP1 (ser65) via Akt activation. Wortmanin, an AKT inhibitor, blocked preconditioning induced mTOR activation and infarct size reduction (39,9 % of risk area, n=6, p<0.05 vs control, NS). These effects of preconditioning were also inhibited either by 5-hydroxydecanoate, an antagonist of mitoKATP (44,4 % of risk area, n=6, p<0.05 vs control, NS) or by rapamycin, a specific inhibitor of mTOR (40 % of risk area, n=7, p<0.05 vs control, NS). Hearts of transgenic mouse overexpressing sFRp1 (α-MHC/sFRP1), a Wnt/Frz antagonist, cardioprotections induced by IPC and PCP were inhibited: sFRP1 impaired GSK3β inhibition and mTOR activation (P70S6K and 4E-BP1 phosphorylation), independently of Akt. We evidenced for the first time that cardioprotection involves a crosstalk between an embryonic developmental Wnt pathway and a survival pathway, mTOR/P70S6K.

Rescue of amitriptyline-intoxicated hearts with nanosized vesicles

Amitriptyline, one of the most prescribed antidepressants, is reported to claim a large number of human lives due to drug overdose related cardiac arrest. Although amitriptyline poisoning has long been recognized as a frequent and serious fatality in the medical field, few efforts have been made to devise methods for treating its toxicity. To address this issue, phospholipid-based nanosized vesicles (spherulites) were employed to reverse the cardiotoxicity induced by amitriptyline in an isolated heart perfusion model. The ability of spherulites to efficiently take up amitriptyline was first established in vitro in protein free and albumin-containing buffers. Vesicles bearing an internal pH of 3.0 or 7.4 were then infused into amitriptyline pre-intoxicated isolated rat hearts, and changes in coronary perfusion pressure (CPP), the first derivative of left ventricular pressure (dP/dt max) and heart rate were monitored. Control hearts received no vesicles. Based on the recoveries in CPP observed, the efficacies of the formulations were ranked as follows: control=pH 7.4-spherulites<pH 3.0-spherulites; whereas the ranking for the recoveries in heart rate was: control<pH 7.4-spherulites<pH 3.0-spherulites. The significantly faster and higher recoveries in pH 3.0- vs. 7.4-spherulite-treated hearts demonstrated the importance of pH-gradient formulation for efficient extraction of tissue-bound amitriptyline. These data suggest that spherulites have a protective effect against acute cardiovascular failure following intoxication with amitriptyline and possibly other cardiotoxic drugs. It appears that the beneficial effects derived from the formulation infusion involved restoration of both haemodynamic and metabolic oxygen demands on the heart.

In vitro electrophysiological mechanisms for antiarrhythmic efficacy of resveratrol, a red wine antioxidant

Resveratrol ( trans-3, 4′, 5-trihydroxystilbene), a natural antioxidant derived from grapes, has beneficial effects against coronary heart disease. Its electrophysiological characteristics for antiarrhythmic efficacy are largely unknown; thus, this study aims to explore the resveratrol's antiarrhythmic effects and conduction system in isolated hearts as well as its electrophysiological effects on cardiac myocytes. In the experiment, resveratrol suppressed the ischemia/reperfusion-induced ventricular arrhythmias in Langendorff-perfused rat hearts. In the current clamp study of the experiment, resveratrol prolonged the action potential duration (APD 50 and APD 90) and suppressed the upstroke velocity of the action potential ( V max). In the voltage clamp study, resveratrol inhibited sodium inward current ( I Na) in a concentration-dependent manner and negative-shifted the voltage-dependent inactivation curve. Resveratrol also reduced the calcium inward current ( I Ca, 51.2 ± 13.3% at 100 μM). Furthermore, the transient ( I to) and sustained ( I ss) outward potassium currents were decreased 60.2 ± 5.7% and 42.3 ± 5.2% after exposure to resveratrol (100 μM), respectively. The inward rectifier potassium current ( I K1) was also reduced 24.2 ± 7.0% in the presence of resveratrol (100 μM). In the isolated heart perfusion model, resveratrol (100 μM) prolonged AV nodal refractory period, the Wenckebach cycle length and the conduction through AV node and His-Purkinje system. In conclusion, resveratrol increased the cardiac effective refractory period mainly through inhibiting the ionic channels including I Na, I to and I ss which could contribute to the conversion of ischemia/reperfusion-induced lethal arrhythmias.

RIGHT VENTRICULAR FUNCTIONAL RECOVERY AFTER ISCHEMIA REPERFUSION INJURY AS A FUNCTION OF VOLUME OVERLOAD

Background: In a recent executive summary, the National Heart Lung and Blood Institute concluded that right heart failure is distinctly different from left heart failure and remains an understudied but important component of cardiovascular collapse. Right heart failure from both acute and chronically elevated right ventricular afterload has been well studied. However, the effect of acute volume overload to the untrained right ventricle is still not well understood. We hypothesized that increasing acute volume overload of the right ventricle affects ventricular functional recovery after ischemia reperfusion (I/R) injury. Methods: Sprague-Dawley rats (weight 250-300 g) were used with a modified Langedorff isolated heart perfusion model with the latex balloon in the right ventricle. The isolated rat hearts were perfused for fifteen minutes after which the hearts were subjected to 25 minutes of global ischemia at 37 degrees C. The hearts were divided into two groups (N = 8 per group). The first group had a physiologic right ventricular balloon pressure (EDP) of 5 mmHg. The second group had a pathologic EDP of 40 mmHg. Function was continuously recorded throughout the experiments. Recovery of right ventricular developed pressure (RVDP), +dP/dt and -dP/dt were assessed. Data are represented as means +/− SEM and differences were considered significant if P < 0.001 (two way ANOVA). Results: Recovery of RVDP, +dP/dt and -dP/dt was significantly higher in the group with lower EDP as compared to the group with 40 mmHg EDP. RVDP: 79.53 +/− 6.34 versus 54.28 +/− 10.76 mmHg; +dP/dt: 76.54 +/− 8.79 versus 38.75 +/− 19.74 mmHg; -dP/dt: 72.29 +/− 7.02 versus 30.54 +/− 12.44 mmHg. Conclusions: Ischemia reperfusion injury produces right ventricular myocardial functional depression that is compounded by preload. The degree of functional depression is greater when the right heart is exposed to higher volume overload. This study is a step forward in elucidating the mechanism and severity of the failing right ventricle that sustains an ischemic insult.

Chronic Erythropoietin Treatment Limits Infarct-size in the Myocardium in Vitro

It has been well established that erythropoietin (EPO) can limit myocardial ischemia/reperfusion injury in a variety of acute settings. However, despite EPO being used chronically to treat anemia the infarct limiting effects of long term treatment (chronic) have never been fully investigated. In this study we examined the effects of a 3 week treatment of EPO (5,000 IU/Kg) in male Sprague Dawley rats in limiting myocardial infarction after 35 min ischemia and 2 h reperfusion in an in vitro isolated heart perfusion model. Treating the animals 'once a week' failed to limit infarct size significantly compared to a saline control (54.1% +/- 3.5 v 52.3% +/- 4.4), whereas a '3 times a week' regime succeeded in significantly reducing infarct size (36.2% +/- 3.2 v 52.3% +/- 4.4, p < 0.05). To demonstrate that the effect was not due to improved oxygen supply caused by a raised hematocrit level, we also administered EPO 24 h prior to ischemia/reperfusion. This treatment again reduced infarct size compared to a saline control (39.9% +/- 4.4 v 58.4% +/- 5.0, p < 0.05). To examine the mechanism of protection we used the PI3K inhibitor wortmannin and the nitric oxide synthase inhibitor L-NAME to try to abrogate EPO mediated protection. Where wortmannin failed to block the effects of EPO (31.7% +/- 6.0 v 36.2% +/- 3.2), L-NAME did abrogate protection (51.6% +/- 5.6 v 36.2% +/- 3.2, p < 0.05). We demonstrate that chronic EPO treatment limits infarct size and that it does so in a nitric oxide dependent manner.

Effect of ursodeoxycholic acid on ischemia/reperfusion injury in isolated rat heart.

In this study, the effects of ursodeoxycholic acid (UDCA) on ischemia/reperfusion injury were investigated on isolated heart perfusion model. Hearts were perfused with oxygenated Krebs-Henseleit solution (pH 7.4, 37 degrees C) on a Langendorff apparatus. After equilibration, isolated hearts were treated with UDCA 20 to 160 microM or vehicle (0.04% DMSO) for 10 min before the onset of ischemia. After global ischemia (30 min), ischemic hearts were reperfused and allowed to recover for 30 min. The physiological (i.e. heart rate, left ventricular developed pressure, coronary flow, double product and time to contracture formation) and biochemical (lactate dehydrogenase; LDH) parameters were evaluated. In vehicle-treated group, time to contracture formation was 21.4 min during ischemia, LVDP was 18.5 mmHg at the endpoint of reperfusion and LDH activity in total reperfusion effluent was 54.0 U/L. Cardioprotective effects of UDCA against ischemia/reperfusion consisted of a reduced TTC (EC25=97.3 microM), reduced LDH release and enhanced recovery of cardiac contractile function during reperfusion. Especially, the treatments of UDCA 80 and 160 microM significantly increased LVDP and reduced LDH release. Our findings suggest that UDCA ameliorates ischemia/reperfusion-induced myocardial damage.

Melanoma cell destruction in the microvasculature of perfused hearts is reduced by pretreatment with vitamin E.

Different mechanisms have been proposed to explain the rapid elimination of circulating malignant cells: interactions with circulating leukocytes, mechanical trauma induced by deformation, shear forces and tissue pressure variations. Based on earlier observations in an isolated heart perfusion model the present study was performed to test whether or not microvascular damage of malignant cells depends on their anti-oxidant status. Murine melanoma B16F10 cells, pretreated with 100 microM alpha-tocopherol (or solvent) for 48 h, were used. The cells were perfused into the coronary vasculature of isolated hearts from C57/BL6 mice. Passing cells were collected and their viability determined by Trypan Blue exclusion. The hearts were processed for electron microscopy and the frequency of ultrastructurally intact and damaged B16 cells trapped in capillaries was recorded. In filter perfusion experiments the effect of vitamin E pretreatment on the resistance of the melanoma cells to mechanical deformation was determined. Morphometrically, cell size and cell profile perimeter excess of the melanoma cells were computed. Vitamin E pretreatment increased perfused cell viability from 50% to 81%. Ultrastructurally 30% of the intracapillary vitamin E treated cells were damaged (plasmalemmal fragmentation or worse) as compared to 58% of control cells. These differences were statistically significant (P < 0.01) whereas no differences could be demonstrated in filterability, cell size, or cell surface excess. The data support the hypothesis that malignant cell destruction in the systemic microcirculation is at least partly dependent on an oxygen metabolite mediated process, the exact nature (e.g. superoxide, hydrogen peroxide, nitric oxide) of which remains to be determined.