Effect of paeonol on L-type calcium channel in rat ventricular myocytes.

In order to study the possible mechanisms of paeonol on the cardiovascular system, the effect of paeonol on L-type Ca(2+) channel current (I(Ca,L)) was studied in rat ventricular myocytes using the whole cell patch-clamp technique. Exposure to paeonol (approximately 10 to 1000 microm/l) resulted in a concentration-dependent inhibition of peak I(Ca,L), with a half maximum inhibition concentration, IC(50), of 561 microm/l. Paeonol 600 microm/l inhibited I(Ca,L) by 55.3%, shifted the steady state activation and inactivation curve of I(Ca,L) to more positive and negative potentials, respectively, tended to prolong the recovery of I(Ca,L) from inactivation and did not have a use-dependent effect. However, the current-voltage relationship and reversal potential of I(Ca,L) were not altered. These results suggest that the protection by paeonol against myocardial injury is due to its blocking effect on I(Ca,L).