Brain membrane disordering after acute in vivo administration of ethanol, isopropanol or t-butanol in rats.

Brain synaptosomal membranes were prepared from rats sacrificed 18 hr after a single intragastric dose of water or of ethanol (100 mmol/kg), when blood ethanol had fallen almost to zero. Fluorescence polarization of DPH, and (Na+ + K+)ATPase activity, were studied in these membranes in the presence of 0, 0.175, 0.3 or 0.7 M ethanol in vitro. After in vivo ethanol, basal ATPase activity was slightly increased, membrane fluidity was unchanged, but both measures showed increased sensitivity to the effects of ethanol in vitro. Similar results were found after an equivalent in vivo dose of isopropanol, but not of t-butanol. These findings indicate that the sensitization to in vitro effects of ethanol or isopropanol, after in vivo treatment with these alcohols, is probably not dependent principally on their lipid solubilities.