Electrophysiological effects of ginseng and ginsenoside Re in guinea pig ventricular myocytes.
Panax ginseng is a folk medicine with various cardiovascular actions; however, its underlying mechanisms of action are not well known. In the present study, we examined the effects of ginseng and its main component, ginsenoside Re, on action potentials and membrane currents recorded from isolated guinea pig ventricular myocytes with the whole-cell patch clamp technique. Ginseng (1 mg/ml) shortened the action potential duration in a rate-dependent manner. Ginseng depressed the L-type Ca2+ current (I(Ca-L)) in a mode of both tonic block and use-dependent block, and enhanced the slowly activating component of the delayed rectifier K+ current (I(Ks)). Ginsenoside Re 3 microM exhibited similar electrophysiological effects to those of 1 mg/ml ginseng, but of slightly smaller magnitude. Inhibition of I(Ca,L) and enhancement of I(Ks) by ginsenoside Re appear to be one of the main electrophysiological actions of ginseng in the heart, although contributions from other ingredients should be considered.
Bai
Chang-Xi
CX
Department of Bio-informational Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, 2-3-10 Kandasurugadai, Chiyoda, Tokyo 101-0062, Japan.
Sunami
Akihiko
A
Namiki
Takao
T
Sawanobori
Tohru
T
Furukawa
Tetsushi
T
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D051668:Delayed Rectifier Potassium Channels; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods*; D036145:Ginsenosides / Q000494:pharmacology*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000502:physiology; D005894:Panax; D018408:Patch-Clamp Techniques; D010936:Plant Extracts / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology; D024642:Potassium Channels, Voltage-Gated
D051668:Delayed Rectifier Potassium Channels; D036145:Ginsenosides; D010936:Plant Extracts; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; C049864:ginsenoside Re