Blocking effect of rhynchophylline on calcium channels in isolated rat ventricular myocytes.
The effect of rhynchophylline (Rhy) on L-type Ca2+ channel current was studied in rat ventricular myocytes using patch-clamp whole-cell recording technique. When the holding potential was -40 mV, cells were depolarized to 0 mV for 250 ms at frequency of 0.5 Hz, Rhy 10 and 50 mumol.L-1 reduced verapamil-sensitive Ca2+ inward current by 60% and 80%, respectively, without affecting the voltage-dependency of the maximal activation of Ca2+ current. This indicated that the effect of Rhy on the activation of Ca2+ channel was voltage-independent. The effect of Rhy on Ca2+ current reached the maximum at 10 min and was partially recovered by washout of Rhy. A pD2 value of 5.91 and Hill coefficient of 1.1 were obtained from the concentration-response curve.
Wang
X L
XL
Institute of Materia Medica, Chinese Academy of Medical Sciences, Beijing.
Zhang
L M
LM
Hua
Z
Z
D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects*; D002478:Cells, Cultured; D006321:Heart / Q000502:physiology; D026121:Indole Alkaloids; D008297:Male; D009206:Myocardium / Q000166:cytology; D000078183:Oxindoles; D051381:Rats; D014700:Verapamil / Q000494:pharmacology
D000470:Alkaloids; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D026121:Indole Alkaloids; D000078183:Oxindoles; C052714:rhyncophylline; D014700:Verapamil