Blocking Effect of Salvianolic Acid A on Calcium Channels in Isolated Rat Ventricular Myocytes

Objective:To study the effect of salvianolic acid A（SAA） on L-type calcium current（l-CaL） in isolated ventricular myocytes of Sprague-Dawley rats.Methods:SAA powder was dissolved in normal Tyrode’s solution to reach the concentrations of 1,10,100,and 1000μmol/L.The traditional whole-cell patch-clamp recording technique was employed to evaluate the effects of SAA on 1-CaL in single ventricular myocytes which were prepared by Langendorff perfusion apparatus from Sprague-Dawley rats.Results:SAA（1,10,100, and 1000μmol/L） inhibited l-CaL peak value by 16.23%±1.3%（n=6,P<0.05）,22.9%±3.6%（n=6,P<0.05）, 53.4%±3.0%（n=8,P<0.01）,and 62.26%±2.9%（n=6,P<0.01）,respectively.SAA reversibly inhibited l-CaL in a dose-dependent manner and with a half-blocking concentration(IC;) of 38.3μmol/L.SAA at 100μmol/L elevated theⅠ-Ⅴcurve obviously,and shifted the half-active voltage(V;) from（-15.78±0.86） mV to（-11.24±0.77） mV（n=6,P<0.05） and the slope（K） from 5.33±0.74 to 4.35±0.74（n=6,P>0.05）.However,it did not alter the shapes ofⅠ-Ⅴcurve,steady-state inactivation curve,or recovery from inactivation curve.Conclusions: SAA inhibited l-CaL in a dose-dependent manner.It shifted the steady-state activation curve to a more positive voltage,which indicated that the drug affected the activated state of calcium channels,and suggested that the Ca;antagonistic effect of SAA be beneficial in the treatment of myocardial ischemia reperfusion injury.