[Effects of stress on L type calcium channels of rat ventricular myocytes]

To observe the effects of stress on Ica-L, steady-state activation curves and steady-state inactivation curves.

Use NE to construct stress cell model, then the whole-cell patch-clamp recording technique 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 [Ca2+]i.

The amplitude of peak current of Ica-L increased significantly, and by analyzing the steady-state activation curve, we found that the curve was shifted to left, the V1/2 of stress group was (-14.59 +/- 0.24 ) mV vs (-0.69 +/- 0.36) mV of control group. The rate of apoptosis was increased from 0.36% to 2.17% (P < 0.01). The [Ca2+]i increased by 16.7%.

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.