ETHANOL ENHANCES INWARD RECTIFICATION IN RAT LOCUS-CERULEUS NEURONS BY INCREASING THE EXTRACELLULAR POTASSIUM CONCENTRATION

Citation
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
Citations number
45
Categorie Soggetti
Pharmacology & Pharmacy
ISSN journal
00223565
Volume
271
Issue
1
Year of publication
1994
Pages
334 - 342
Database
ISI
SICI code
0022-3565(1994)271:1<334:EEIRIR>2.0.ZU;2-F
Abstract
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.