[Inactivation of Na+, K+ -ATPase from cattle brain by sodium fluoride].
The influence of the physiological ligands and modifiers on the plasma membrane Na+, K+ -ATPase from calf brain inactivation by sodium fluoride (NaF) is studied. ATP-hydrolyzing activity of the enzyme was found to be more stable as to NaF inhibition than its K+ -pNPPase activity. The activatory ions of Na+, K+ -ATPase have different effects on the process of the enzyme inhibition by NaF. K+ intensifies inhibition, but Na+ does not affect it. An increase of [Mg2+free] in the incubation medium (from 0.5 to 3.0 mM) rises the sensitivity of Na+, K+ -ATPase to NaF inhibition. But an increase of [ATP] from 0.3 to 1.5 mM has no effect on this process. Ca and Mg ions modify Na+, K+ -ATPase inhibition by fluoride differently. Ca2+free levels this process, and Mg2+free on the contrary increases it. In the presence of Ca ions and in the neutral-alkaline medium (pH 7.0-8.5) the recovery of activity of the transport ATPase inhibited by-NaF takes place. Sodium citrate also protects both ATP-hydrolizing and K-pNPPase activity of the Na+, K+ -ATPase from NaF inhibition. Under the modifing membranous effects (the treatment of plasma membranes by Ds-Na and digitonin) the partial loss of Na+, K+ -ATPase sensitivity to NaF inhibition is observed. It is concluded that Na+, K+ -ATPase inactivation by NaF depends on the influence of the physiological ligands and modifiers as well as on the integrity of membrane structure.
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Kravtsov
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D000818:Animals; D001921:Brain / Q000201:enzymology*; D002118:Calcium / Q000494:pharmacology; D002417:Cattle; D002462:Cell Membrane / Q000187:drug effects* / Q000201:enzymology; D002951:Citrates / Q000494:pharmacology; D004072:Digitonin / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007700:Kinetics; D008024:Ligands; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D000077559:Sodium Citrate; D012969:Sodium Fluoride / Q000494:pharmacology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*
D002951:Citrates; D004791:Enzyme Inhibitors; D008024:Ligands; D000077559:Sodium Citrate; D012969:Sodium Fluoride; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium; D004072:Digitonin; D002118:Calcium