Ss. Osmanovic et Sa. Shefner, ETHANOL ENHANCES INWARD RECTIFICATION IN RAT LOCUS-CERULEUS NEURONS BY INCREASING THE EXTRACELLULAR POTASSIUM CONCENTRATION, The Journal of pharmacology and experimental therapeutics, 271(1), 1994, pp. 334-342
The effect of ethanol on the current-voltage relationship of rat locus
ceruleus (LC) neurons was examined under voltage-clamp conditions in
a totally submerged brain slice preparation. LC neurons have the class
ic K+-specific type of inward rectification (IR), which is blocked by
Ba++ and Cs+. Ethanol (40-200 mM) was found to enhance IR in LC neuron
s; it increased both the maximal slope conductance and shifted the vol
tage range for activation of IR in the depolarizing direction. These e
ffects of ethanol were concentration dependent and fully reversible on
washout. When IR was blocked with Ba++ or intracellular acetate, etha
nol increased the slope conductance of the linear current-voltage rela
tionship but did not restore IR. Ethanol also reduced the amplitude of
afterhyperpolarizations that follow individual action potentials and
trains of action potentials in LC neurons. Ethanol caused a depolarizi
ng shift in the K+ equilibrium potential and its effects on IR could b
e mimicked by an increase in the K+ concentration in the medium. Speci
fically, 100 mM ethanol, on average, shifted the K+ equilibrium potent
ial by 6.3 mV and its enhancement of IR was mimicked by an increase in
the external K+ of 0.5-0.7 mM. From these data, it was concluded that
ethanol enhances IR in LC neurons by increasing the extracellular Kconcentration.