Inhibitory effects of vinpocetine on sodium current in rat cardiomyocytes.
OBJECTIVE
To study the effects of vinpocetine (Vin) on the sodium current (INa) in cardiomyocytes.


METHODS
The sodium current in adult rat ventricular myocytes was measured by whole cell patch-clamp technique.


RESULTS
The INa in cardiomyocytes was blocked reversibly by Vin, in concentration-dependent and voltage-dependent manner, but not rate- or use-dependent. The INa was attenuated by 13%-75% when the Vin concentration was raised from 10 to 80 mumol.L-1. The IC50 (95% confidence limits) was 36.4 (28.1-47.1) mumol.L-1. When the membrane potential depolarized over the range of -90 mV to +40 mV in 10-mV step, inhibitory effect of Vin on the INa was 39% at first, then maintained at a higher level, about 52% +/- 5%. The maximal depression (57%) reached at about 0 mV. Vin influenced both the activation and inactivation processes of sodium channel, and resulted in attenuation of the window currents (the slowly inactivating sodium currents).


CONCLUSIONS
Vin inhibited sodium currents in rat ventricular myocytes.
D000818:Animals; D008297:Male; D009206:Myocardium / Q000166:cytology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D015222:Sodium Channels / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology*; D014748:Vinca Alkaloids / Q000494:pharmacology*