Effects of ethanol on calcium transport across the liver cell plasma membrane.
The effect of ethanol on calcium transport by the liver cell was studied by using a rat liver slice preparation. Ethanol was shown to decrease by about 30% the rate constant for 45Ca efflux from the intracellular compartment. This inhibitory effect of ethanol was not observed in the absence of Ca2+ or Na+ from the incubation medium. Ethanol was also shown to greatly increase non-insulin calcium uptake by liver slices. This effect of ethanol appeared to be dose dependent and was not observed in the absence of Na+ from the incubation medium. The ability of ethanol to increase calcium uptake by the hepatocyte was completely blocked by 1 mM Amiloride. Amiloride, however, did not affect the increased entry of either Na+ or Ca2+ produced by 10 mM Ouabain, a specific inhibitor of the sodium pump. Carbon tetrachloride (CCl4), a well known hepatotoxin, also increased calcium uptake by the hepatocyte. Amiloride, however, was not able to block the CCl4-induced calcium uptake. These results suggest that ethanol activates a Na+ entry pathway, probably represented by a Na+/H+ exchanger, which in turn stimulates an entry of Ca2+ through a Na+/Ca2+ exchange mechanism located in the plasma membrane of the hepatocyte.
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D002251:Carbon Tetrachloride / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D000431:Ethanol / Q000494:pharmacology*; D066298:In Vitro Techniques; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism
D002132:Calcium Radioisotopes; D000431:Ethanol; D010042:Ouabain; D000584:Amiloride; D012964:Sodium; D002251:Carbon Tetrachloride; D002118:Calcium