title: Evidence for a plasma membrane calcium pump in bovine adrenal medulla but not adrenal cortex.
abstract: Continuous sucrose density gradient subfractions from bovine adrenal medullary microsomes were found to accumulate 45-Ca-2+ in the presence of ATP and ammonium oxalate mainly in subfractions of intermediate density. (Na-++K-+)-ATPase (plasma membrane marker) and Ca-2+-ATPase activities were also concentrated in these intermediate subfractions but thiamine pyrophosphatase (Golgi apparatus marker) was not. NADH oxidase (endoplasmic reticulum marker) activity was distributed throughout all subfractions. 45-Ca-2+ accumulation in adrenal cortical microsomes was found to rise and fall in parallel with thiamine pyrophosphatase but not with (Na-++K-+)-ATPase or NADH oxidase activities. Accumulation of 45-Ca-2+ in membrane vesicles in these experiments suggests the existence of a calcium transfer mechanism in plasma membranes of the adrenal medulla but not adrenal cortex.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000302:Adrenal Cortex / Q000378:metabolism*; D000311:Adrenal Glands / Q000378:metabolism*; D000313:Adrenal Medulla / Q000378:metabolism*; D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism*; D002499:Centrifugation, Density Gradient; D004789:Enzyme Activation / Q000187:drug effects; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008854:Microscopy, Electron; D008861:Microsomes / Q000378:metabolism / Q000648:ultrastructure; D009928:Organ Specificity; D011188:Potassium / Q000494:pharmacology; D011955:Receptors, Drug; D012964:Sodium / Q000494:pharmacology; D013834:Thiamine Pyrophosphatase / Q000378:metabolism
chemical_list: D011955:Receptors, Drug; D012964:Sodium; D000251:Adenosine Triphosphatases; D013834:Thiamine Pyrophosphatase; D008274:Magnesium; D011188:Potassium; D002118:Calcium