外源性磷脂酸对心室肌细胞钙电流的作用

目的：观察外源性磷脂酸（PA）对豚鼠心室肌细胞钙电流的影响。方法：Langendorff离体心脏逆向灌流法分离豚鼠心室肌细胞，随机选取心室肌细胞分为：正常对照组，PA 0.01、0.1和1.0 μmol·L^-13个剂量组，百日咳毒素（PTX）0.1 mg·L^-1+PA 1.0 μmol·L^-1组，蛋白激酶C(PKC)阻断剂H-7 2 μmol·L^-1+PA 10　μmol·L^-1组。应用全细胞电压钳方法分别记录各组心室肌细胞Ca²⁺电流。结果：外源性PA 0.01、0.1 和1 mmol·L^-1分别使豚鼠心室肌细胞L-型钙电流（L-I_Ca）由给药前的（288.70±28.33）、（290.83±25.12）和（279.54±31.22）pA增加到给药后的（304.10±28.31）（P>0.05）、（349.80±30.13）(P<0.01)和（388.10±28.12）pA(P<0.001)；加入G-蛋白耦联受体阻断剂PTX和PKC阻断剂H-7后，PA对²⁺通道电流的作用与给药前比较差异无显著性。结论：外源性PA可增加豚鼠心室肌细胞的L-I_Ca电流，其作用机制是通过膜受体-G蛋白-PKC通路发挥作用。

Effects of exogenous phosphatidic acid on calcium current of ventricular myocytes

Objective To study the effects of exogenous phosphatidic acid(PA) on calcium current of ventricular myocytes.Methods The Langendorff perfusion method was used to isolate the ventricular myocytes of guinea pigs and the ventricular myocytes of guinea pigs were randomly divided into control group,three dosage groups of PA 0.01,0.1 and 1.0 μmol ·L~(-1)and group of PTX 0.1 mg ·L~(-1) plus PA 1.0 μmol·L~(-1)and group of H-7(2 μmol·L~(-1)) plus PA 1.0 μmol·L~(-1).The whole cell voltage clamp technique was used to record the calcium current of isolated ventricular myocytes of guinea pigs.Results 0.01,0.1 and 1.0 μmol·L~(-1) PA enhanced the calcium current from(288.70±28.33)pA,(290.83±25.12)pA and(279.54±31.22)pA before administration to(304.10±28.31)pA(P>0.05),(349.80±30.13)pA(P<0.01) and(388.10±28.12)pA(P<0.001) after administration.The effects of PA on the calcium current was blocked by PTX(a G protein-coupled receptor blocking agent) and H-7(a PKC blocking agent).Conclusion PA can promote the opening of calcium channels of the ventricular myocytes by the pathway of membrane receptor-G protein-PKC in a dose-dependent manner.