The synergistic effect of tetrandrine and rotundine on the action potential of rabbit sinus node dominant pacemaker cell and calcium currents of ventricular myocytes from guinea-pig
Yan, S.; Yao, W.X.; Xia, G.J.; Tong, Q.S.; Jiang, M.X.
Yao Xue Xue Bao 32(3): 161-165
1997
ISSN/ISBN: 0513-4870 PMID: 11327013 Document Number: 478032
Standard microelectrode technique and the whole-cell clamp technique were used to investigate the effects of tetrandrine and rotundine on the action potential of rabbit sinus node dominant pacemaker cell and calcium currents of ventricular myocytes from guinea-pig. The results indicate that: tetrandrine 1 apprx 200 mu-mol cntdot L-1 and rotundine 3 apprx 300 mu-mol cntdot L-1 decreased the action potential amplitude(APA), the maximal upstroke velocity (Vmax), spontaneous depolarizing velocity of phase 4(SP-4) and prolonged the sinus circle length(SCL) in a dose-dependent manner. Tetrandrine 0.1 mu-mol cntdot L-1 in combination with rotundine 0.3 mu-mol cntdot L-1 was shown to effectively reduce the I-Ca of ventricular myotytes from guinea-pig, the rate of inhibition is 19.6%. The results suggest that the two drugs have a good synergistic effect on inhibiting calcium current. These results might also put foreword a valuable theoretic base for using the two drugs together in treating patients.