title: Inhibition of rat brain microsomal Na+,K+-ATPase by S-adenosylmethionine.
abstract: Rat brain microsomes were preincubated with S-adenosylmethionine (SAM), MgCl2, and CaCl2, then reisolated, and the activity of Na+,K+-ATPase determined. SAM inhibited the Na+,K+-ATPase activity compared with microsomes subjected to similar treatment in the absence of SAM. A biphasic inhibitory effect was observed with a 50% decrease at a SAM concentration range of 0.4 microM-3.2 microM and a 70% reduction at a concentration range above 100 microM. Inclusion of either S-adenosylhomocysteine or 3-deazaadenosine in the preincubations prevented the SAM inhibition of Na+,K+-ATPase activity. The inhibition by SAM appeared to be Mg2+- or Ca2+-dependent.
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D006710:Homocysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D050356:Lipid Metabolism; D008745:Methylation; D008861:Microsomes / Q000201:enzymology*; D051381:Rats; D012436:S-Adenosylmethionine / Q000494:pharmacology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D014372:Tubercidin / Q000494:pharmacology
chemical_list: D006710:Homocysteine; D012436:S-Adenosylmethionine; C007957:homocysteine thiolactone; D000254:Sodium-Potassium-Exchanging ATPase; D014372:Tubercidin