钙预适应对膨胀离体大鼠心室所致心律失常的影响

为了证实钙预适应对膨胀离体大鼠心室所诱发的心律失常具有抑制作用 ,采用Langendorff方法灌流离体大鼠心脏。用正常灌流液灌流平衡后 ,离体心被随机分为 4组 :牵张对照组 ,钙预适应组 ,钙预适应 +维拉帕米组和钙预适应 +格列本脲组。维拉帕米和格列本脲在灌流液中的浓度分别为 1μmol/L和 10 μmol/L ,对钙预适应进行干预后及时用正常灌流液将他们从离体心洗脱。将可充灌液体的乳胶球囊通过左房及二尖瓣置于左室 ,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 ,观察心电图ST段和T波的变化 ,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 :通过乳胶球囊膨胀左室 ,使左室舒张末压增加相同的情况下 ,对照组心律失常总发生率达 10 0 % ,持续时间为 2 .5 6± 0 .4 6s ;钙预适应组较对照组心律失常总发生率明显降低 (40 % ) ,持续时间缩短到 1.6 7± 0 .6 1s(P均 <0 .0 5 ) ;用维拉帕米对钙预适应进行干预后 ,心律失常总发生率较钙预适应组增高 (90 % ) ,持续时间延长 (2 .5 0± 0 .4 6s) ;钙预适应 +格列本脲组心律失常发生情况和钙预适应组相似。各组离体心在膨胀前后冠脉流量和心率、心电图ST段和T波均未见明显变化。结论 :?

Influence of Ca2+ Preconditioning on Ventricular Dilation-induced Arrhythmias in Isolated Rat Hearts

To test the hypothesis that Ca 2+ preconditioning(CPC)inhibits ventricular dilation induced arrhythmias in isolated rat hearts, isolated rat hearts were perfused by Langerdorff method. After equilibration of perfusion with normal buffer,the hearts were randomly divided into four groups:Stretch control group,CPC group,Verapamil + CPC group and glybenclamide + CPC group. Verapamil whose concentration was 1μmol/L and glybenclamide whose concentration was 10μmol/L were washed out after hearts subjected to CPC were treated with them respectively. A latex balloon which can be filled with fluid was anchored within the left ventricle through the left atrium and mitral valve. Epicardial ECG of the left ventricle, left ventricular pressure, coronary flow and heart rate were recorded and changes of ST and T wave of ECG were observed before and during ventricular dilation by injecting fluid into the latex balloon, and then the incidence rate and duration of ventricular dilation induced arrhythmias were calculated. Results:The total incidence rate of arrhythmias was 100% and duration of arrhythmias was 2.56±0.46s in the control group. Compared with the control group, the total incidence rate(40%)of arrhythmias was lower and duration(1.67 ± 0.61s)of arrhythmias was shorter in CPC group.The incidence rate of arrhythmias(90%)was higher and duration(2.50 ± 0.46s)of arrhythmias was longer in verapamil + CPC group than in CPC group. The results in glybenclamide + CPC group were similar to those in CPC group. Conclusions: It′s the transient increase in [Ca 2+ ] i but not the activation of K ATP channel that is supposed to play an important role in the procedure of CPC.