胡椒碱对H2O2致兔心房肌细胞动作电位时程及L型钙电流异常的保护作用

目的:研究胡椒碱(PIP)对H2O2引起的单个兔心房肌细胞动作电位时程（APD）及L型钙电流(ICa,L)异常的保护作用。方法:采用全细胞膜片钳技术，观察10和50 μmol/L的H2O2引起单个兔心房肌细胞APD及ICa,L的改变，以及预先应用7 μmol/L的PIP对其的作用。结果:7 μmol/L的PIP对正常兔心房肌细胞APD、ICa,L及L型钙通道动力学无明显影响。在10和50 μmol/L的H2O2作用下，兔心房肌细胞APD50和APD90明显缩短(P<0.05)，静息膜电位（RMP）绝对值显著下降(P<0.05)，ICa,L峰值由(39.3±5.4) pA/pF降低至(32.8±2.0) pA/pF(P<0.05)，电流-电压曲线上移，通道稳态激活曲线右移，通道稳态失活曲线左移，但恢复时间不变。预先给予7 μmol/L的PIP可明显减轻H2O2对APD、ICa,L的抑制作用(P<0.01)，对L型钙通道动力学的异常影响。结论:PIP可减轻氧化应激对心房肌细胞APD、ICa,L的影响。

Protective effect of piperine on abnormalities of action potential duration and L-type calcium current induced by hydrogen peroxide in rabbit atrial myocytes

AIM: To study the protective effect of piperine on the abnormalities of action potential duration and L-type calcium current(ICa,L) induced by hydrogen peroxide in single rabbit atrial myocyte.METHODS: Whole-cell patch clamp technique was used to study the effect of H2O2(10 and 50 μmol/L) on APD and ICa,L in single rabbit atrial myocyte and the effect of pretreatment with piperine(7 μmol/L).RESULTS: Piperine(7 μmol/L) had no significant effect on APD and ICa,L of normal single rabbit atrial myocyte as well as its channel dynamics.In the presence of 10 and 50 μmol/L H2O2,APD50 and APD90 decreased(P<0.05),amplitude of RMP disincreased(P<0.05),the peak of ICa,L was significantly reduced(P<0.05),I-V curve shifted upward,steady-state activation curve of ICa,L was shifted to positive potentials,and steady-state inactivation was shifted to negative potentials,but recovery from inactivation of ICa,L showed no remarkable changes.Piperine(7 μmol/L) significantly alleviated the inhibitory effect of H2O2 on APD and ICa,L(P<0.01) and protected the changes of ICa,L dynamics induced by H2O2.CONCLUSION: Piperine can alleviate abnormalities of APD and ICa,L induced by hydrogen peroxide in atrial myocytes.