兔急性心肌梗死后梗死周边带心肌细胞L-型钙通道的变化

探讨L型钙通道在急性心肌梗死 (AMI)后室性心律失常发生中的作用及其机制。方法 :以开胸冠状动脉结扎法制备兔AMI模型 ,1周后处死动物分离心室肌细胞 ,采用全细胞膜片钳记录技术观察梗死周边缺血带心外膜心室肌细胞L型钙通道电流 (ICa L)的变化 ,以正常心肌ICa L为对照。结果 :AMI 1周时兔梗死周边区心室肌细胞L型钙电流受到抑制 ,其电流峰值由正常状态下的 - 5 .58± 1 .53pA/pF(对照组 ,n =1 0 )降至 - 3 .52± 0 .93pA/pF(AMI组 ,n=6) ,最大峰电流下降 2 9.1 % ,P <0 .0 5 ,I V曲线上移 ;其失活曲线左移 ,半数最大失活电位由 - 1 3 .1± 4 .2mV左移至 - 2 5 .9± 7.0mV ,P <0 .0 5 ,失活速度加快。结论 :AMI后 1周梗死周边带心外膜心室肌细胞L型钙通道受抑制 ,可能为AMI后室性心律失常发生的机制之一。

Changes of L-type Calcium Channel of Myocytes in Peri-infarcted Zone of Rabbit Infarcted Models One Week After Infarction

To determine the changes of L-type calcium currents(I Ca-L ) of rabbit ischemic myocytes in peri-infarcted zone after acute myocardi al infarction(AMI),rabbit AMI models were made by ligation of branches of left coronary artery.After 1 week,single ventricular epicardial myocytes were isolate d enzymatically from ischemic zone adjacent to infarcted area and the normal con trol cells from similar regions in normal rabbit hearts.I Ca-L were record e d by using patch clamp techniques in the whole cell configuration.Results:Peak o f I Ca-L of ischemic cells from the peri-infarcted zone was significantly reduced (-3.52±0.93 pA/pF, n =6) compared to control cells (-5.58±1.53 pA/p F, n =10), P <0.05,the peak decreased nearly 1/3.The steady-state inactivat ion curve was shifted to the hyperpolarizing direction in ischemic cells,the hal f-maximal voltage dependence of inactivation(V 1/2 ) was -25.9±7.0 mV in i s chemic cells and -13.1±4.2 mV in the control cells.Conclusion:Inhibitation of I Ca-L was found in the ischemia zone cells and might be important in the d evelopment of ventricular arrythmias after AMI.