Effects of ginkgo biloba extract on cation currents in rat ventricular myocytes.
Ginkgo biloba extract (GBE), a valuable natural product for cerebral and cardiovascular diseases, is mainly composed of two classes of constituents: terpene lactones (e.g., ginkgolide A and B, bilobalide) and flavone glycosides (e.g., quercetin and kaempferol). Its electrophysiological action in heart is yet unclear. In the present study, using whole-cell patch clamp technique, we investigated electrophysiological effects of GBE on cation channel currents in ventricular myocytes isolated from rat hearts. We found that GBE 0.01-0.1% inhibited significantly the sodium current (I(Na)), L-type calcium current (I(Ca)) and transient outward potassium current (IK(to)) in a concentration-dependent manner. Surprisingly, its main ingredients, ginkgolide A (GB A), ginkgolide B (GB B) and bilobalide (GB BA) at 0.1 mM did not exhibit any significant effect on these cation channel currents. These results suggested that GBE is a potent non-selective cation channel modulator in cardiaomyocytes. Other constituents (rather than GB A, GB B and GB BA) might be responsible for the observed inhibitory effects of GBE on cation channels.
Chen
Biyi
B
Section of Learning and Memory, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China. bichen@iupui.edu
Cai
Jingxia
J
Song
Long-Sheng
LS
Wang
Xiaoqing
X
Chen
Zhihe
Z
D000818:Animals; D020746:Calcium Channels, L-Type / Q000187:drug effects; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D020441:Ginkgo biloba; D006352:Heart Ventricles; D007473:Ion Channels / Q000187:drug effects*; D008297:Male; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology*; D015221:Potassium Channels / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D015222:Sodium Channels / Q000187:drug effects
D020746:Calcium Channels, L-Type; D007473:Ion Channels; D010936:Plant Extracts; D015221:Potassium Channels; D015222:Sodium Channels; D004121:Dimethyl Sulfoxide