膨胀缺血预适应离体大鼠心脏所致心律失常及其机制

目的　研究缺血预适应 (ischemicpreconditioning ,IPC)条件下膨胀离体大鼠心脏所诱发的心律失常及链霉素对其影响。方法　采用Langendorff方法灌流离体大鼠心脏。将可充灌液体的乳胶球囊通过左心房及二尖瓣置于左心室 ,通过向乳胶球囊注射液体对左室进行膨胀 ,记录膨胀前和膨胀过程中左室心电图和左室压力 ,冠脉流量和心率 ;并计算对照组和各实验组由膨胀诱发心律失常的发生率和持续时间。结果　通过乳胶球囊膨胀离体大鼠左室可诱发对照组和IPC组发生心律失常 ;在左室舒张末压增加相同的情况下 ,IPC组较对照组室性早搏和室性心动过速发生率均降低 ,持续时间缩短 ;链霉素干预后 ,IPC心脏心律失常发生情况明显改善。结论　对离体大鼠心室进行膨胀可诱发心律失常 ;IPC条件下大鼠心脏对牵张的耐受性增强 ,链霉素对膨胀IPC离体大鼠心脏所致心律失常具有抑制作用。

Mechanism of ventricular dilation- induced arrhythmias in isolated rat hearts with ischemic preconditioning

Objective To investigate ventricular dilation-induced arrhythmias in isolated rat hearts subjected to ischemic preconditioning (IPC) and the effects of streptomycin. Methods Isolated rat hearts were perfused by Langerdorff method. A latex balloon which can be filled with fluid was anchored within the left ventricle through the left atrium and mitral valva. Epicardial ECG of the left ventricle, left ventricular pressure, coronary flow and heart rate were recorded before and during ventricular dilation by injecting fluid into the latex balloon. The incidence and duration of ventricular dilation-induced arrhythmias were calculated. Results Ventricular dilation induced arrhythmias by injecting fluid into the latex balloon in both control group and IPC group. With same increase of ventricular end-diastolic pressure, incidence of premature ventricular beats and ventricular tachycardia was lower and the duration of arrhythmias was shorter in IPC group than those in the control group. Less ventricular dilation-induced arrhythmias occurred when hearts subjected to IPC were treated with streptomycin. Conclusion Ventricular dilation may induce arrhythmias in isolated rat hearts. The IPC hearts are more tolerant to stretch than the contrtol ones. Streptomycin inhibits the effects of mechanical stretch on ventricular dilation-induced arrhythmias in rat hearts subjected to IPC.