Effect of shenmai injection on L-type calcium current of diaphragmatic muscle in rats.

In this study, whole cell patch clamp recording technique was employed to investigate the effect of Shenmai Injection (SMI) on L-type calcium current of diaphragmatic muscle in rats. The result showed that when the diaphragmatic muscle cell was held at -80 mV and depolarized to +60 mV, 10 microl/ml, 50 microl/ml and 100 microl/ml SMI enhanced the inner peak L-type calcium current from -(6.8 +/- 0.7) pA/pF (n=7) to -(7.3 +/- 0.8) pA/pF (P>0.05, n=7), -(8.6 +/- 1.0) pA/pF (P<0.05, n=7) and -(9.4 +/- 1.2) pA/pF (P<0.05, n=7), respectively, The rates of L-type calcium current were increased by (7.34 +/- 2.37)%, (25.72 +/- 5.94)%, and (38.16 +/- 7.33)%, respectively. However, it had no significant effect on maximal activation potential and reversal potential. Our results suggested that SMI could activate the calcium channel of the diaphragmatic fibers of the rats, increase the influx of Ca2+, and enhance the contractility of diaphragmatic muscles.