['SS and LS mice have been used to explore the genetic and neurochemical bases for differences in sensitivity to ethanol. The present study investigated the effects of ethanol on GABAA receptor function in microsacs from these genotypes. The purpose was to test a key element of the hypothesis that differences between these lines in sensitivity to ethanol-induced enhancement of GABAA receptor function underlie their selected differences in sensitivity to ethanol-induced loss of righting reflex (LORR).', 'The effects of ethanol on GABA-activated 36Cl- uptake in brain membranes (microsacs) isolated from male SS and LS mice were tested using a chloride flux filtration assay.', 'Ethanol significantly enhanced GABA-activated 36Cl- uptake in SS microsacs at concentrations of 100-300 mM. Ethanol did not significantly affect GABA-activated chloride uptake in this preparation at concentrations of 25 and 50 mM. Ethanol significantly enhanced GABA-activated 36Cl- uptake in LS microsacs at concentrations of 25-100 mM, but not at 200 mM.'] Does ethanol enhance GABAA receptor function in short sleep and long sleep mouse brain membranes?