title: Vanadyl (VO2+) induced lipoperoxidation in the brain microsomal fraction is not related to VO2+ inhibition of Na,K-ATPase.
abstract: Vanadyl (VO2+) is a potent inductor of the lipid peroxidation in brain microsomes. This effect, however, is obtained at concentrations by two orders of magnitude higher (10(-4)-10(-3)M) than those which effectively inhibit the brain microsomal Na,K-ATPase. At 10(-6)M VO2+ which inhibits 50% of the Na,K-ATPase activity there is no measurable malonyldialdehyde production. Vanadate (VO-3) which is an equally potent inhibitor of Na,K-ATPase as VO2+ has almost no capacity to induce the lipoperoxidation. The addition of 10(-4)M ascorbate to the brain microsomes stimulates the lipoperoxidation to the maximum level regardless of the presence or absence of exogenous vanadium ions. Ascorbate-induced inhibition of brain Na,K-ATPase which is known to be associated with lipoperoxidation is strictly additive with the vanadyl (VO2+) inhibition of this enzyme. Even at submaximal concentrations there is no indication for any potentiation between these two inhibitory systems. The disparity between the mechanisms of ascorbate and vanadyl-induced inhibition of Na,K-ATPase is also documented by the effect of EDTA which inhibits the former type only. It is concluded, that the vanadium-induced inhibition of brain microsomal Na,K-ATPase is not related to induction of lipoperoxidative capacity of the brain.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D017301:Ca(2+) Mg(2+)-ATPase; D004492:Edetic Acid / Q000494:pharmacology; D066298:In Vitro Techniques; D008054:Lipid Peroxides / Q000096:biosynthesis*; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D014639:Vanadium / Q000494:pharmacology*
chemical_list: D008054:Lipid Peroxides; D014639:Vanadium; D004492:Edetic Acid; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D000254:Sodium-Potassium-Exchanging ATPase; D001205:Ascorbic Acid