IMPROVEMENT OF ISCHEMIC TOLERANCE AND COLD PRESERVATION OF AGED MYOCARDIUM BY TRANSFECTION OF HEAT-SHOCK PROTEIN GENE

1.缺血耐受性随年龄增长而降低：在分离自12、50或100周龄Fischer 344大鼠的心脏中，分析了左心室功能和能量代谢物的恢复、心肌酶（CPK和LDH）的释放以及缺血再灌注心律失常。根据langendorff技术，使心脏经受15至25分钟的缺血和30分钟的再灌注。功能和代谢产物的恢复以及酶的释放证明了缺血耐受性的年龄依赖性降低。缺血再灌注心律失常在老年大鼠心脏中也更恶性。结论：1.缺血或缺氧预处理对老年心脏缺血再灌注损伤无明显改善作用，甚至加重心肌损伤.基因转染：HVJ-脂质体+质粒法转染热休克蛋白（HSP）基因的心肌细胞中，只有30%的细胞能检测到HSP。该百分比在转染后24、48或72小时之间没有差异。当阳离子HVJ-脂质体 ...更多信息 使用时，效率没有显著提高。抗HSP抗体免疫细胞化学分析显示，HSP在内皮细胞中的阳性率较高，提示阳离子HVJ脂质体可能在到达心肌细胞之前就被截留在内皮细胞中.冷停搏液后保存和HSP转染热的缺血再灌注损伤：任何年龄的心脏经HSP基因转染后，心脏经冷停搏液10 min后再保存2 h，其功能和代谢产物的恢复以及酶的释放都有改善的趋势，但HSP转染并不能减少缺血再灌注心律失常。另一方面，缺血25 min再灌注30 min的心脏功能和代谢物的恢复、酶的释放和缺血再灌注心律失常的改善不明显.离体心肌细胞模拟缺血：转染HSP基因的任何年龄的心肌细胞，在模拟缺血（缺氧，pH6.5，乳酸20 mM，k12 mM）3 min后，细胞内Ca的增加减弱，细胞运动恢复加快。少

1. Decrease in ischemic tolerance with aging: Recovery of left ventricular function and energy metabolites, release of myocardial enzymes (CPK and LDH), and ischemia-reperfusion arrhythmias were analyzed in hearts isolated from 12, 50 or 100 week-old Fischer 344 rats. Hearts were subjected to 15 to 25 min of ischemia and 30 min of reperfusion according to the langendorff technique. Recovery of function and metabolites and release of enzymes demonstrated age-dependent decrease in ischemic tolerance. Ischemic-reperfusion arrhythmias were also more malignant in older rat hearts. Ischemic or hypoxic preconditioning performed before prolonged ischemia did not have any beneficial effects or even deteriorated myocardial damage in older hearts.2. Gene transfection: Heat shock protein (HSP) was detected only 30% of myocytes transfected with HSP gene using HVJ-liposome+plasmid methods. This percentage was not different between 24, 48 or 72 hours after transfection. When cationic HVJ-liposome was … More used, efficiency was not improved remarkably. Immunocytochemical analysis with anti-HSP antibody revealed that HSP was detected with high incidence in endothelial cells, which suggested cationic HVJ-liposome might be trapped in the endothelial cells before reaching to myocytes.3. Preservation after cold cardioplegia and iscchemia-reperfusion injury in HSP-transfected heats: Recovery of function and metabolites and release of enzymes in hearts subjected to 10 min cold cardioplegia followed by 2 hours preservation were tended to be improved when hearts of any age were transfected with HSP gene, although ischemia-reperfusion arrhythmias were not decreased by HSP transfection. On the other hand, recovery of function and metabolites, release of enzymes, and ischemia-reperfusion arrhythmias in hearts subjected to 25 min of ischemia and 30 min of reperfusion showed only insignificant improvement.4. Simulated ischemia in isolated myocytes: In myocytes of any age that were transfected with HSP gene, increase in intracellular Ca was attenuated and recovery of cell motion was improved after 3 min of simulated ischemia (hypoxia, pH6.5, lactate 20mM, k12mM). Less