title: NaK-ATPase in rat pancreatic islets.
abstract: Shifts in the distribution of the monovalent cations Na+ and K+ between the extra- and intracellular space seem to be important for the secretory response of the beta-cell. An attempt was therefore made to study the enzyme responsible for monovalent cation transport, the (NaK)-activated ATPase. In the presence of NaN3 as inhibitor of the mitochondrial Mg-ATPase, a NaK-ATPase with a specific activity of 72 mU X mg protein-1 could be demonstrated in crude membrane preparations of rat pancreatic islets. The enzyme, which was inactive in the absence of Mg++, needed both Na+ and K+ for activation and was inhibited by ouabain and PCMB. The main part of the NaK-ATPase was localized in the microsomal fraction. Glucose, sulphonylureas, somatostatin and diazoxide were without effect on NaK-ATPase.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D001386:Azides / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D002729:Chloromercuribenzoates / Q000494:pharmacology; D007515:Islets of Langerhans / Q000201:enzymology*; D008274:Magnesium / Q000378:metabolism; D008297:Male; D008861:Microsomes / Q000201:enzymology; D008928:Mitochondria / Q000201:enzymology; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D012964:Sodium / Q000378:metabolism*; D014508:Urea / Q000494:pharmacology
chemical_list: D001386:Azides; D002729:Chloromercuribenzoates; D010042:Ouabain; D014508:Urea; D012964:Sodium; D000251:Adenosine Triphosphatases; D008274:Magnesium; D011188:Potassium