Ethanol effects on active and passive Na+ flux in toad bladder.
Ethanol, like other anesthetics, has been reported to interfere with active Na+ transport in living membranes. In an attempt to elucidate the mechanism by which ethanol exerts this action, we tested in the toad bladder membrane: 1) the effect of ethanol on active Na+ transport, 2) the interaction of ethanol with vasopressin on Na+ transport, and 3) the effect of ethanol on passive Na+ flux. We found that, a) 1-500 microgram/ml of ethanol stimulated, and 10,000 microgram/ml depressed active Na+ transport; b) the combined effect of stimulating concentrations of ethanol and vasopressin, although suggestive of a positive interaction, might have arisen by chance (p = 0.08); c) depressant concentrations of ethanol failed to suppress the stimulation by vasopressin; and d) passive Na+ flux in bladders treated with ouabain and ethacrynic acid was not affected by ethanol (1-100 microgram/ml). These results indicate that ethanol in concentrations ranging from 1 to 10,000 microgram/ml does not block ATP/ATPase Na+ pump but apparently exerts a dose-dependent, stimulant-depressant effect on Na+ channels in the membrane.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001693:Biological Transport, Active / Q000187:drug effects; D002024:Bufo marinus; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D001743:Urinary Bladder / Q000187:drug effects* / Q000378:metabolism; D014667:Vasopressins / Q000494:pharmacology
D014667:Vasopressins; D000431:Ethanol; D012964:Sodium