Effects of in vitro ethanol on the brain cation pump in alcoholics and controls.
In vivo ethanol exposure reduces in vitro Na+,K(+)-adenosine triphosphatase (Na+,K(+)-ATPase) sensitivity to ethanol in some animal models, but very little is known about the effects of ethanol on human brain Na+,K(+)-ATPase. Cerebral cortex homogenates from 13 male alcoholic and 9 control subjects were assayed for K(+)-p-nitrophenylphosphatase (K(+)-pNPPase, a measure of Na+,K(+)-ATPase) and Mg(2+)-pNPPase activities at 37 degrees for 20 min in 75 mM imidazole-HCl (pH 7.4), 5 mM p-nitrophenylphosphate, 5 mM MgCl2, and 20 mM KCl, with or without 1 mM ouabain. Native K(+)-pNPPase activites were similar in control and alcoholic brains (61.5 +/- 3.5 vs 55.3 +/- 3.1 nmol/mg/min). In vitro exposure to a near lethal ethanol level (0.5%, or 110 mM) was without effect, whereas 5% ethanol inhibited K(+)-pNPPase activity by about 28% (P < 0.001) in both groups. Both 0.5 and 5% ethanol in vitro significantly stimulated Mg(2+)-pNPPase activity (1-2% and 19-20%, respectively). By comparison, mouse brain K(+)-pNPPase was inhibited significantly by in vitro ethanol, and Mg(2+)-pNPPase activity was unaffected. Ethanol levels attainable in humans may not be sufficient to alter significantly brain Na+,K(+)-ATPase activity.
Bertoni
J M
JM
Department of Neurology, Creighton University, Omaha, NE 68131.
Sprenkle
P M
PM
D009597:4-Nitrophenylphosphatase / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000437:Alcoholism / Q000378:metabolism*; D000818:Animals; D001923:Brain Chemistry; D000431:Ethanol / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008875:Middle Aged; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013045:Species Specificity
D000431:Ethanol; D009597:4-Nitrophenylphosphatase; D000254:Sodium-Potassium-Exchanging ATPase