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机械敏感性离子通道是心脏机械电反馈的机电传导器,目前认为其与心律失常的发生有关.近年来,细胞骨架对离子通道的调控得到广泛研究.本实验旨在探讨紫杉醇是否能够抑制牵张缺血心肌所诱导的电生理改变.32只wistar大鼠随机分为4组:对照组(n=9)、紫杉醇组(n=7)、心梗组(n=9)和心梗+紫杉醇组(n=7).经langendorff离体灌流后,以0.2和0.3mL的幅度对离体心脏进行牵张,分别为5s,观察牵张效应30s,包括90%的单相动作电位、室性早搏和室速.结果发现,牵张后,正常对照组和心梗组MAPD90均延长,且同等牵张幅度下心梗组MAPD90延长得更为明显.紫杉醇(5μmol/L)对于基础状态下的MAPD90无影响.牵张后,紫杉醇MAPD90较正常对照组轻度延长(P>0.05).但紫杉醇可使心梗组心肌牵张后的MAPD90缩短(ΔV=0.3mL时,P<0.05).心梗组PVB和VT的发生率高于正常对照组(均P<0.01).紫杉醇对正常心肌的心律失常发生无影响,但可抑制梗死心肌PVB和VT的发生(均P<0.01).综上,紫杉醇可明显抑制急性心肌梗死离体大鼠心脏牵张时,MAPD的改变和心律失常的发生,提示紫杉醇可能参与到急性心肌梗死时的机械电反馈过程.
Mechanically sensitive ion channels are electromechanical transducers of cardiac electromechanical feedback, which are thought to be related to the occurrence of cardiac arrhythmia.In recent years, the regulation of cytoskeleton on ion channels has been extensively studied.This experiment aimed to investigate whether paclitaxel can inhibit stretch The electrophysiological changes induced by ischemic myocardium were observed in all rats.All the 32 Wistar rats were randomly divided into 4 groups: control group (n = 9), paclitaxel group (n = 7), myocardial infarction group (n = 9) (N = 7) .After perfused in vitro by langendorff, isolated hearts were stretched at a rate of 0.2 and 0.3 mL, respectively, for 5 s. The distraction effect was observed for 30 s, including 90% of single-phase action potentials, Premature beat and ventricular tachycardia.The results showed that MAPD90 in normal control group and myocardial infarction group were prolonged after stretch, and the MAPD90 in myocardial infarction group was more prolonged in the same stretch amplitude.Patients with paclitaxel (5μmol / L) (P> 0.05), paclitaxel shortened myocardial MAPD90 after myocardial stretch (ΔV = 0.3mL, P <0.05) .There was no difference between the two groups The incidence of PVB and VT was higher than that of the normal control group (all P <0.01). Paclitaxel had no effect on arrhythmia of normal myocardium (P <0.01) .To sum up, paclitaxel can obviously inhibit the changes of MAPD and arrhythmia in isolated heart of acute myocardial infarction rats, suggesting that paclitaxel may Participate in mechanical and electrical feedback during acute myocardial infarction.