title: Modulations of rabbit erythrocyte ATPase activities induced by in vitro and in vivo exposure to ethanol.
abstract: Alcohol intake is associated with numerous degenerative disorders, and the detrimental effects of alcohol may be due to its influence on plasma membrane and cellular transport systems. The aim of the present study was to compare in vitro and in vivo effects of ethanol on rabbit erythrocyte ATPase activities and correlate them with ethanol-induced oxidative stress. Age-matched male rabbits were given 5% ethanol in 2% sucrose solution, for 6 weeks ad libitum; control animals were given tap water. Daily intake of ethanol was 5 g/kg body weight; this experimental regimen resulted in an average serum ethanol concentration of 16.77 +/- 2.00 mM/l. After this period, blood was collected, serum ethanol concentration was determined and erythrocyte membranes were prepared according to the method of Post et al. Activities of Na(+)/K(+)- and Mg(2+)-ATPases were determined. Thiobarbituric acid-reactive substance (TBARS) assay was used to detect levels of lipid peroxidation, a major indicator of oxidative stress. In vitro ethanol inhibits both Na(+)/K(+)-ATPase and Mg(2+)-ATPase, but Na(+)/K(+)-ATPase is more sensitive to the ethanol-induced inhibition. Increasing concentration of ethanol increased TBARS production, but significant difference was attained only at 5 and 12.5 mM of ethanol. Chronic ethanol consumption induced significant increase in Na(+)/K(+)- and Mg(2+)-ATPase activity, and TBARS production. Our results suggest that increased ATPase activity induced by chronic ethanol consumption is due to oxidative, induced modification of membrane phospholipids and proteins, which are responsible for inhibition of ATPase activity. Increased production of TBARS induced by in vitro exposure to ethanol is not the only factor that influences ATPases activity. Further research is needed to elucidate this relationship.
authors.affiliation: Institute of Physiology, School of Medicine, University of Belgrade, Visegradska 26/II, 11000 Belgrade, Serbia.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Rasić-Marković
authors.forename: Danijela
authors.initials: D
authors.lastname: Krstić
authors.forename: Zorana
authors.initials: Z
authors.lastname: Vujović
authors.forename: Vladimir
authors.initials: V
authors.lastname: Jakovljevic
authors.forename: Olivera
authors.initials: O
authors.lastname: Stanojlović
authors.forename: Dragan
authors.initials: D
authors.lastname: Hrncić
authors.forename: Dragan
authors.initials: D
authors.lastname: Djurić
authors.forename: Helena
authors.initials: H
authors.lastname: Loncar-Stevanović
mesh_terms: D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism*; D002469:Cell Separation; D004910:Erythrocyte Membrane / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects* / Q000201:enzymology*; D000431:Ethanol / Q000008:administration & dosage / Q000494:pharmacology*; D015227:Lipid Peroxidation / Q000187:drug effects; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D011817:Rabbits; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
chemical_list: D017392:Thiobarbituric Acid Reactive Substances; D000431:Ethanol; D017301:Ca(2+) Mg(2+)-ATPase; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium