Inhibitory effect of tetrahydropalmatine on calcium current in isolated cardiomyocyte of guinea pig
XU Chun, SUN Ming-Zhi, LI Yu-Rong, YANG Bao-Feng, WANG Li-Juan, LI Jin-Ming (Department of Physiology, Department of Pharmacology, Harbin Medical University, Harbin 150086, Department of Pharmacology, China Medical University, Shenyang 110001, China)
AIM: TO study the effect of tetrahydropalmatine (THP) on calcium channels in ventricular single cells of guinea pig heart. METHODS: Patch-clamp technique (whole cell recording) was used to observe calcium current in ventricular myocytes. RESULTS: THP decreased Ica in ventricular myocytes with a dose and frequency-dependent manner. THP (0.1, 1, and 10 μmol · L-1) decreased Ica from 1. 15 ± 0. 22, 0. 91 ±0.18, and 1. 60 ± 0. 42 nA (control) to 0. 9 ±0.21 (P0.01), 0.56±0.21 (P0.01), and 0.83±0.21 nA(P0.05), respectively, number of cells is five in each group (n = 5), and the rates of the depression of Ica were 22 %, 38 %, and 48 %, respectively. The effect was easily reduced by washing the cell with the Tyrode's solution. The current-voltage relation curve showed that the potential producing peak value of Ica was 0 mV at which THP had the most markedly inhibited action on Ica When the stimulating frequency was changed, Ica varied in a frequency-dependent manner 5 min after THP was given, and the inhibition of THP was stronger at 2 Hz than that at 0.1 Hz. CONCLUSION: THP possessed a Ca2± channel blocking effect.
【CateGory Index】： R96