胺碘酮急性灌流对左室肌3层心肌细胞动作电位和L-型钙离子流异质性的影响

Heterogeneity of Action Potential and Ica-L in Left Ventricular Myocytes and Acute Electrophysiological Effects of Amiodarone

目的:研究正常兔心室内膜心肌(Endo)细胞、心外膜心肌(Epi)细胞及中层心肌(M)细胞的动作电位时程(APD)、跨壁离散度(TDR)和3层心肌细胞的L-型钙通道(Ica-L)电流的异质性,以及胺碘酮急性灌流对上述生理指标的影响。方法:以混合气-二型胶原酶解法分离30只兔左室游离壁3层心肌,采用全细胞膜片钳记录生理台氏液和10μmol/L浓度胺碘酮急性灌流时的动作电位(AP)和Ica-L电流,并记录APD20、APD50及APD90。结果:(1)生理台式液下APD以M细胞最长,Endo细胞最短;胺碘酮处理后Endo细胞的APD20、APD50及APD90,Epi细胞的APD20、APD50与生理台式液比较均延长(P<0.05),M细胞的APD20、APD50、APD90缩短(P<0.05);胺碘酮处理后3层心肌细胞的APD20、APD50及APD90比较,差异无统计学意义(P>0.05)。胺碘酮处理后TDR较生理台氏液下明显减小,差异有统计学意义(P<0.001)。(2)生理台式液下各组电流密度差异有统计学意义(P<0.05);胺碘酮急性灌流对3层心肌细胞的Ica-L均有所抑制,但只有M细胞处理前后差异有统计学意义(P<0.05),胺碘酮对3层心肌细胞的电流电压(I-V)曲线形态和Ica-L电压依赖性无显著影响。结论:兔3层心肌细胞的动作电位存在明显的异质性,应用胺碘酮后APD减小,但不影响3层心肌细胞的Ica-L形态。

Objective： To investigate the action potential duration （APD） and transmural dispersion of repolarization （TDR） and Ica-L ion current of three layers of left ventricular cardiomyocytes in normal rabbit ventricular endomyocardial （Endo） cells, epicardial myocardial （Epi） ceils and midmyocardium （M） ceils, and the acute electrophysiological effects of amiodarone on both APD and TDR thereof. Methods： Thirty rabbit hearts were isolated by O2 and CO2 mixed-gas combined with type -Ⅱ collagenase enzymatic method. The sub-Endo and sub-Epi tissues were separated from M cells.The separated ventricular myocytes were perfused with Tyred＇s solution and 10 μmol/L amiodarone. And then the whole cell patch clamp technique was used to study the AP and Ica-L Results： （1） For APD. M cells were the longest and Endo cells were the shortest. After acute amiodarone perfusion, the APD 20, 50 and 90 were sharply shortened in M cells （P 〈 0.05）. On the contrary,the APD 20, 50 and 90 in Endo ceils and the APD 20, 50 and 90 in Epi ceils were significantly prolonged （P 〈 0.05）. After acute amiodarone perfusion, there was no significant difference between APD 20, 50 and 90 of the three myocardial layers （P 〉 0.05）, but TDR was significantly decreased （P〈0.001）. （2） There were significant differences in the current density between groups （P 〈 0.05）. Ica-L was inhibited in three layers of left ventricular cardiomyocytes after acute amiodarone perfusion. There was a significant change in M cells after treatment of amiodarone （P 〈 0.05）. There were no significant differences in the I-V curve and voltage-dependence of three-layer myocytes after treatment of amiodarone. Conclusion： The AP was significandy different in the three myocyte layers. Amiodarone could decrease the TDR, but had no influence on configuration of Ica-L.