陈旧性心肌梗死时兔心室肌细胞瞬间外向钾电流的变化

Alteration of transient outward potassium current in ventricular myocytes of remote myocardial infarction

目的 观察陈旧性心肌梗死时心室肌细胞瞬间外向钾电流 (Ito)的变化 ,探讨心律失常发生的离子机制。方法 采用结扎兔冠状动脉左前降支的方法建立急性心肌梗死动物模型 ,2个月后处死动物并分离心室肌细胞 ,应用膜片钳全细胞记录方法 ,观察心肌梗死后 2个月心外膜梗死区 (MI)、远离梗死区 (REM )与正常对照组 (CON)心室肌细胞Ito的变化。结果 ①心肌梗死后 2个月REM组心肌细胞电容为 ( 15 5 .7± 5 .8)pF ,明显大于CON组的 ( 12 0 .3± 6.2 ) pF和MI组的( 13 0 .4± 7.8) pF(P <0 0 5 ) ,MI组与CON组相比无统计学差异 (P >0 0 5 )。②Ito电流密度 ( +60mV时 )的对比显示 ,CON组为 ( 17.4± 5 .2 ) pA pF (n =16) ,MI组为 ( 10 6± 4 1) pA pF (n =18) ,明显低于CON组 (P <0 0 1) ;REM组为 ( 13 .2± 4 1)pA pF(n =2 3 ) ,明显低于CON组 (P <0 0 1) ,但明显高于MI组 (P <0 0 5 )。 结论 心肌梗死后心室肌细胞Ito电流密度的变化 。

Objective To study the altertations of the current density of transient outward current(I to ) in myocytes from the epicardial zone of 2 month infarcted rabbit heart.Methods Rabbits were infarcted by ligation of the left anterior descending coronary artery.2 months later,single ventricular myocytes were isolated enzymatically from the infracted area (MI),region remote from the infracted zone(>4mm)(REM) and free wall of left venricule from noninfarcted heart(CON).I to was recorded using whole cell patch clamp technique.Results After 2 monthes of infartion, membrane capacitance of REM myocytes was(155.7±5.8)pF,signifitantly larger than those in CON(120.3±6.2)pF and MI(130.4±7.8)pF, P <0 05.There was no significant difference between MI and CON( P >0 05).I to current density (at +60mV) was significantly decreased in MI(10.6±4.1)pA/pF ( n =18)and REM(13.2±4.1)pA/pF( n =23) compared with CON(17 4±5 2)pA/pF( n =16)( P <0 01).However,there was significant increase in REM compared with MI( P< 0 05).Conclusions After 2 month of infarction,alterations in I to of rabbit ventricular myocytes might be the ion basis of reentrant arrhymias in the infarcted heart.