β_2肾上腺素能受体在心肌梗死大鼠离体心脏牵张所致心律失常中的作用

目的观察β2肾上腺素能受体(β2受体)在心肌梗死(MI)大鼠牵张所致心律失常中的作用,评价β2受体是否参与了机械电反馈。方法复制大鼠MI模型,同时设立假手术组。饲养8周后随机分为假手术组、假手术+ICI118.551组、MI组、MI+ICI118.551组,进行Langendorff离体心脏灌流。自制球囊对左室进行牵张。记录并测量牵张后30s内各组单相动作电位时程(MAPD)、50%和90%MAP复极时程(MAPD50和MAPD90),计算牵张诱发心律失常(SIA)的发生率。结果牵张后,MI组、假手术组MAPD、MAPD50和MAPD90均缩短(P<0.01或<0.05),且MI组缩短更明显;应用ICI118.551后,假手术组MAPD、MAPD50和MAPD90仍缩短(P<0.05),而MI组MAPD、MAPD50和MAPD90差异无显著性(P(0.05)。牵张后,MI组SIA的发生率较假手术组高(22.44%vs10.34%,P<0.05),应用ICI118.551后,假手术组SIA发生率下降,但差异无显著性(P(0.05);MI组SIA发生率明显下降(P<0.01)。结论β受体可能参与了机械电反馈过程。

The effect of β2-adrenoceptor on stretch-induced arrhythmia of isolated hearts after myocardial infarction in rats

Objective To investigate the effect of β2-adrenoceptor on stretch-induced arrhythmia of isolated hearts after myocardial infarction(MI) in rats.To evaluate the effect of β2-adrenoceptor on mechanoelectric feedback.Methods MI models were induced by ligating coronary arteries.After 8 weeks,hearts were isolated and perfused by the Langendorff instrument.36 Wistar rats were randomly divided into 4 groups:sham operation group,sham operation +ICI118.551 group,MI group and MI+ ICI118.551 group.Balloon inflation in the left ventricle of the isolated heart increased the left ventricle preload and dilated the left ventricle.After ICI118.551(10-6mol/L) was administrated through Langendorff instrument,the dilation of the left ventricle was carried out.The monophasic action potential(MAP) of the anterior left ventricle wall of rat hearts was recorded.The effect of stretching was observed for 30s,including MAP duration(MAPD),50% and 90% MAP duration(MAPD50,MAPD90),premature ventricular beats(PVB) and ventricular tachycardia(VT).Results After the stretch,MAPD,MAPD50,and MAPD90 were shortened in both MI group and sham operation group,but it was significant in MI group.After administration of ICI118.551,MAPD,MAPD50,and MAPD90 were still shortened in sham operation group(P<0.05),but there was no difference in MI group(P〈0.05).After the stretch,the incidence rate of SIA in MI group was higher than that in sham operation group(22.44% vs 10.34%,P<0.05).After administration of ICI118.551,the incidence rate of SIA decreased in sham operation group,but there was no statistical difference(P〉0.05);yet it decreased obviously in MI group(P<0.01).Conclusion β2-adrenoceptor might be involved in mechanoelectric feedback process.