Inhibitory effect of ethanol on voltage-dependent potassium currents in single aortic smooth muscle cells

The effect of ethanol on voltage-dependent K+ currents was examined in single aortic smooth muscle cells. The aortic smooth muscle cells were isolated from guinea pigs. The tight-seal patch clamp technique in whole cell configuration was employed. Ethanol (500 mM) reversibly inhibited voltage-dependent transient outward K+ current, the spontaneous transient oscillatory K+ current (STOC) and steady-state K+ current, whereas ethanol (50 mM) did not produce any change in these K+ currents. When the peak-height amplitudes of STOC were analyzed, the application of ethanol (50 mM) was noted to produce significant inhibition on both amplitude and frequency of STOC evoked at the holding potential of +10 mV. The results shown in the present study indicate that ethanol-induced inhibition of the voltage-dependent K+ channel, which is not required for the elicitation of either GTP-binding protein(s) or inositol triphosphate, may contribute to its vasoconstrictor effect because the inhibition of the voltage-dependent K+ channel may lead to the increase of cell excitability in vascular smooth muscle.