OBJECTIVETo observe the effects of the separate and joint use of salvianolic acid B (SalB) and tetrahydropalmatine (THP) on the L-type calcium channel of rat ventricular myocytes.

METHODSSingle isolated ventricular myocytes of rats were obtained using acute enzymolysis separation. The current of the L-type calcium channel was recorded using whole-cell patch clamp technique. Changes of the current peak value of the calcium channel (the vertical distance between the peak value point after activation of the calcium electric current and the electric current track after complete inactivation) were observed before and after medication.

RESULTSThe inhibition rate of using SalB (at the dose of 1, 10, and 100 micromol/L) alone on the current peak value of the calcium channel was respectively (25.3 +/- 16.4)% (n=4), (44.6 +/- 24.0)% (n=6), and (86.0 +/- 20.4)% (n =4). That of using THP (at the dose of 10, 30, and 100 micromol/L) alone on the current peak value of the calcium channel was respectively (22.2 +/- 6.4)% (n=5), (27.4 +/- 1.6)% (n= 3), and (51.0 +/- 23.0)% (n=9). The inhibition potency of joint use of SalB (1 micromol/L) and THP (10 micromol/L) on the current peak value of the calcium channel was stronger than using SalB (1 micromol/L) alone or THP (10 micromol/L) alone, showing statistical difference ( P< 0.05). Atropine hydrochloric acid (14 mmol/L) could reverse the inhibition of THP on the L-type calcium channel, while strengthening the inhibition of SalB.

CONCLUSIONSBoth SalB and THP showed inhibition on the L-type calcium channel of rat ventricular myocytes. They could generate synergistic effects. Besides, their action mechanisms for regulating the L-type calcium channel were different.