应激对大鼠心室肌细胞L-型钙离子通道的影响

EFFECTS OF STRESS ON L TYPE CALCIUM CHANNELS OF RAT VENTRICULAR MYOCYTES

目的 :研究应激对心室肌细胞L 型钙离子通道电流及激活、失活门控动力学特性的影响。方法 :制备离体心室肌细胞并用去甲肾上腺素 (NE)诱导建立应激心肌细胞模型 ,应用流式细胞术 (FCM )和Fura 2荧光分光光度法测定应激心室肌细胞的凋亡率和心肌细胞内游离钙浓度变化。利用膜片钳全细胞钳制记录法记录应激心室肌细胞L 型钙离子通道电流I V曲线图及稳态激活、失活曲线图。结果 :FCM检测发现 1 0 - 4mol/L的NE模拟应激可导致心室肌细胞凋亡率明显上升 ,对照组 :0 .36 % ,应激组 :2 .1 7% (P <0 .0 1 )。 1 0 - 4mol/L的NE干预使Ica L峰电流幅值显著性上升 ,激活曲线分析发现应激后曲线明显左移 ,半数最大激活膜电位 (V1 /2 )为 (- 1 4 .59± 0 .2 4 )mV ,较之于对照组 :(- 0 .69± 0 .36)mV ,差异显著 ,而稳态失活曲线特性未发生有意义的改变。实验组心肌细胞内游离钙浓度较对照组升高 1 6 .7%。结论 :应激可导致L 型钙离子通道电流增加 ,通道更易于激活 ,通道的这种异常活动可能导致钙超载 ,从而引起心肌细胞凋亡 。

Aim: To observe the effects of stress on Ica-L,steady-state activatio n curves and steady-state inactivation curves. Methods: Use N E to construct stress cell model, then the whole-cell patch-clamp recording te chnique was used to record the Ica-L, the steady-state activation curves and the steady-state inactivation curves. With FCM technique,we observed the rate of apoptosis of cardiomyocytes. By dying cells with Fura-2 and fluorometry, we determined [Ca 2+ ]i. Results: The amplitude of peak c urrent of Ica-L increased significantly, and by analyzing the steady-state ac tivation curve,we found that the curve was shifted to left, the V 1/2 of st ress group was (-14.59±0.24 )mV vs (-0.69±0.36)mV of control group. The ra te of apoptosis was increased from 0.36% to 2.17% ( P <0. 01).The [Ca 2+ ]i increased by 16.7%. Conclusion: Stress can bring on increasing of Ica-L, and the channels are easy to be activated. These changes can cause ' calcium overload' and then induce apoptosis which lead to injury of myocytes in stress.