极化心脏停搏液对离体大鼠心脏的保护作用

Protective effects of polarizing cardioplegic solution in isolated rat hearts

目的 探讨 Na+通道阻滞剂河豚毒素 (tetraodontoxin,TTX)在极化状态下对离体大鼠心脏的保护作用。 方法 将 2 0只 Wistar大鼠按体重均衡原则随机分成两组 ,每组 10只。取出心脏建立 L angendorff灌注模型和左心工作灌注模型 ,分别用去极化心脏停搏液 (St.Thomas2号液 ,STH- 2组 )和极化心脏停搏液 (2 2 μm ol/ L TTX+K- H缓冲液 ,TTX组 )停搏 ,低温保存 5小时后再灌注心脏。观察两组心脏缺血前、后在心功能、心肌酶漏出量、三磷酸腺苷酶 (ATPase)活性、再灌注后心肌胞浆游离 Ca2 +浓度和心肌超微结构等方面的改变。 结果 恢复灌注后 ,TTX组心功能恢复明显优于 STH- 2组 (P<0 .0 1) ,心肌酶漏出量较少 (P<0 .0 5 ) ,各种 ATPase维持较高的活性 (P<0 .0 1) ,胞浆游离 Ca2 + 浓度明显低于 STH- 2组 (P<0 .0 1) ,心肌超微结构得到很好的保护。 结论 以 TTX阻断 Na+通道为特点的极化心脏停搏液对大鼠心肌缺血 -再灌注损伤的保护作用优于去极化心脏停搏液 ,有希望成为新型、有效的心脏停搏液和供者心脏保存液。

Objective To investigate the protective effects of polarizing cardioplegic solution by sodium channel inhibitor tetraodontoxin(TTX) in isolated rat hearts. Methods Twenty Wistar rats were randomly divided into two groups,each group 10 rats. A Langendorff perfusion model and working left ventricular perfusion model was sequentially used.The hearts were arrested by polarizing cardioplegic solution(Krebs-Henseleit buffer solution +22 μmol/L TTX,TTX group) or by depolarizing cardioplegic solution(St.Thomas No.2 solution,STH-2 group).These hearts were subjected to 5 hours of storage at 7℃ in the corresponding arrest solution. Preischemic and postischemic cardiac function during reperfusion were measured. The leakages of creatine kinase (CK),lactic dehydrogenase (LDH) were measured by assaying coronary sinus venous solution.Left ventricular myocardial samples were collected for measuring the activities of Na+-K+-ATPase,Ca 2+-ATPase and Ca 2+-Mg 2+-ATPase, additionally for observing myocardial ultrastructure with transmission electron microscopy.The intracellular free calcium concentrations ( i) were detected by using the fluorescent Ca 2+-indicator Fluo-3/AM. Results There were no significant differences between two groups before myocardial ischemia.But the percentage of myocardial function during reperfusion in TTX group was better than that in STH-2 group(P<0.01).The releases of CK and LDH were less in TTX group(P<0.05). The activities of Na+-K+-ATPase,Ca 2+-ATPase and Ca 2+-Mg 2+-ATPase in TTX group were significantly higher than those in STH-2 group(P<0.01). i was lower in TTX group than that in STH-2 group(P<0.01). Myocardial ultrastructure was better protected in TTX group. Conclusion TTX can prevent Na +-overload and reduce the consumption of high energy phosphate by arresting heart under polarizing conditions,therefore,plays an important role in myocardial protection.