title: Effects of manganese on rat brain microsomal Mg2+-Na+-K+-ATPase: in vivo and in vitro studies.
abstract: The effect of manganese on brain microsomal Mg2+-Na+K+-ATPase was examined both in vitro and in vivo. Daily intraperitoneal administration of MnCl2 . 4H2O (Mn2+, 6 mg/kg) to the rats for a period of 90 days produced 10% (P less than 0.05) inhibition in the activity of Mg2+-ATPase, and 72 and 63% increases in the contents of manganese and copper, respectively, in the microsomal fraction of brain. In in vitro studies, lower concentrations of Mn2+ activated while higher concentrations inhibited the activity of brain microsomal ATPase. Addition of equal concentrations of Mn2+ + Cu2+ (8 mM) in vitro produced 8% inhibition in the activity of Mg2+-ATPase and 83% inhibition in Na+-K+-ATPase. Free Cu2+ ions were able to antagonize the effect of Mn2+ on ATPase in vitro and inhibited the activity of Mg2+-Na+-K+-ATPase with more pronounced effect of Na+-K+-ATPase. The lack of change in the activity of Na+-K+-ATPase in the brain microsomes of rats administered manganese, in spite of a significant increase in copper, could not be explained. It is, however, evident that a manganese-induced elevation in brain copper was not responsible for initiating biochemical changes in manganese neurotoxicity.
mesh_terms: D000818:Animals; D001921:Brain / Q000201:enzymology*; D003300:Copper / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008345:Manganese / Q000494:pharmacology*; D008861:Microsomes / Q000201:enzymology*; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
chemical_list: D008345:Manganese; D003300:Copper; C030704:magnesium sodium potassium ATPase; D000254:Sodium-Potassium-Exchanging ATPase