Effect of rhyncophylline on potassium channels in isolated rat or guinea pig ventricular myocytes.
Effects of rhyncophylline (Rhy) on the voltage-dependent potassium channels in isolated rat and guinea pig ventricular myocytes were studied by using patch clamp whole cell recording techniques. Rhy was found to reduce the steady-state outward current in rat ventricular myocytes when cells were depolarized from holding potential -40 mV to 0 mV. After blocking Ca2+ inward current with CdCl2 0.1 mmol/L, a K+ transient outward current (IA) can be recorded. Rhy 30 mumol/L inhibited the IA 30% when depolarized to +50 mV from the holding potential. The delayed outward (IK) and outward tail current (I(tail)) were also reduced 30% and 60%, respectively by Rhy 30 mumol/L which responded to 4.5 sec long pulse from -40 mV to +50 mV. Whereas, the inward rectifying current (IK1) was not changed by Rhy. The present study suggests that the antiarrhythmic action of Rhy was partially due to the K+ channel blocking effects.
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; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D006168:Guinea Pigs; D026121:Indole Alkaloids; D009206:Myocardium / Q000166:cytology*; D000078183:Oxindoles; D015221:Potassium Channels / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
D000470:Alkaloids; D000889:Anti-Arrhythmia Agents; D026121:Indole Alkaloids; D000078183:Oxindoles; D015221:Potassium Channels; C052714:rhyncophylline