title: [The influence of iron ions on ATP-hydrolases activity of cell membranes of rat colon smooth muscle and kidney].
abstract: To elucidate the specific features of the ATP-hydrolases structural resistance in the membrane under the action of the prooxidants: Fe2' and hydrogen peroxide, and N-ethylmaleimide (NEM) the colonic smooth muscle (CSM) Na+, K(+)-ATPase activity was compared with activities of the corresponding Mg(2+)-ATP-hydrolase and ATPases from kidney medullar layer of rats. The inhibition study of the CSM Na+, K(+)-ATPase by divalent iron shows the decrease of the activity by 30% at 0.1 μM FeSO4 and in the range of 0.1-10 μM--to 45% of residual activity. When comparing with kidney enzyme (rep- resents exclusively α1-isozyme) the CSM Na+, K(+)-ATPase sensitivity to Fe2+ is reliably higher at its submicromolar concentration. CSM Mg2+-ATPase is much more resistant to iron ions effect, than kidney one. However for two tissues Mg2(+)-ATPase activity is always more resistant as compared with corresponding Na+, K(+)-ATPase activity. Against 1 mM EGTA Na+,K(+)-ATPase and Mg2(+)-ATPase activities of GMOK and kidneys are equally insensitive to effect of hydrogen peroxide in concentration up to 1 mM. But in the presence of 20 μM FeSO4 in the concentration range of 1 nM-1 mM of H2O2 the Na+, K(+)-ATPase is inhibited to greater extent, than Mg2+-ATPase activity. NEM sensitivity of the two ATP-hydrolase systems corresponds to prooxidant sensitivity that indicates the distinct importance of SH-groups for their functioning. It is concluded that Na+, K+-ATPase can serve as a marker of membrane sensitivity to oxidation, Mg(2+)-ATPase is resistant to oxidation and can be considered as criterion of the oxidation resistance when comparing membrane enzyme complexes, es- pecially in GMOK.
authors.forename: A A
authors.initials: AA
authors.lastname: Kaplia
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism*; D002413:Cations, Divalent; D002462:Cell Membrane / Q000187:drug effects* / Q000201:enzymology; D003106:Colon / Q000187:drug effects / Q000201:enzymology; D004533:Egtazic Acid / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D005296:Ferrous Compounds / Q000494:pharmacology*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D006868:Hydrolysis; D007679:Kidney Medulla / Q000187:drug effects / Q000201:enzymology; D007700:Kinetics; D009130:Muscle, Smooth / Q000187:drug effects / Q000201:enzymology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000201:enzymology; D009928:Organ Specificity; D016877:Oxidants / Q000494:pharmacology*; D010084:Oxidation-Reduction; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D002413:Cations, Divalent; D005296:Ferrous Compounds; D016877:Oxidants; C020748:ferrous sulfate; D004533:Egtazic Acid; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D017301:Ca(2+) Mg(2+)-ATPase; D000254:Sodium-Potassium-Exchanging ATPase; D005033:Ethylmaleimide