Ethanol may stimulate or inhibit (Na+ + K+)-ATPase, depending upon Na+ and K+ concentrations.
The influence of varying the ratios of [Na+]/[K+] on the effects of alcohol (500 mg/dl) on brain (Na+ + K+)-ATPase, using a commercial porcine enzyme preparation, showed that, generally, activity was stimulated by ethanol when [Na+] less than [K+], but inhibited when [Na+] greater than [K+] (with sum kept constant at 150 mM). In addition, when [Na+]/[K+] was 15/90 mM, representative of normal intracellular levels, ethanol (500 mg/dl) stimulated the porcine enzyme, but inhibited it when [Na+]/[K+] was 144/6 mM, representative of normal extracellular levels. Similarly, in freshly prepared enzyme from highly purified rat brain synaptic membranes, ethanol (100, 300, and 450 mg/dl) stimulated when [Na+]/[K+] was 15/88 mM (representing intracellular levels), but inhibited when [Na+]/[K+] was 142/4 mM (extracellular levels).
Foster
D M
DM
Olin E. Teague Veterans' Center, Department of Medical Pathology, TexasA&M University, Temple 76504.
Huber
M D
MD
Klemm
W R
WR
D000818:Animals; D001921:Brain / Q000378:metabolism* / Q000648:ultrastructure; D002462:Cell Membrane / Q000378:metabolism; D000431:Ethanol / Q000494:pharmacology*; D008861:Microsomes / Q000378:metabolism; D009994:Osmolar Concentration; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013552:Swine
D000431:Ethanol; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium