Inhibitory effects of vinpocetine on sodium current in rat cardiomyocytes
Abstract
AIM: 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).
CONCLUSION: Vin inhibited sodium currents in rat ventricular myocytes.
Keywords:
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).
CONCLUSION: Vin inhibited sodium currents in rat ventricular myocytes.