title: Subunit composition and role of Na+,K+-ATPases in adrenal chromaffin cells.
abstract: Adrenal medullary (AM) cells are exposed to high concentrations of cortical hormones, one of which is a ouabain-like substance. Thus, the effects of ouabain on catecholamine secretion and distribution of Na+,K+-ATPase alpha and beta subunits in rat and guinea-pig AM cells were examined using amperometry and immunological techniques. While exposure to 1 microm ouabain did not have a marked effect on resting secretion, it induced an increase in secretion due to mobilization of Ca2+ ions that were stored during a 4 min interval between muscarine applications. Immunocytochemistry revealed that Na+,K+-ATPase alpha1 subunit-like and beta3 subunit-like immunoreactive (IR) materials were distributed ubiquitously at the cell periphery, whereas alpha2- and beta2-like IR materials were present in restricted parts of the cell periphery. The alpha1 and alpha2 subunits were mainly immunoprecipitated from AM preparations by anti-beta3 and anti-beta2 antisera, respectively. Peripheral BODIPY-FL-InsP3 binding sites were localized below membrane domains with alpha2- and beta2-like IR materials. The results indicate that in AM cells, alpha1beta3 isozymes of Na+,K+-ATPase were present ubiquitously in the plasma membrane, while alpha2beta2 isozymes were in the membrane domain closely associated with peripheral Ca2+ store sites. This close association of the alpha2beta2 isozyme with peripheral Ca2+ store sites may account for the facilitation of mobilization-dependent secretion in the presence of 1 microm ouabain.
authors.affiliation: Department of Physiology, Fukuoka University School of Medicine, Fukuoka, Japan.
authors.forename: Hai
authors.initials: H
authors.lastname: Lin
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Ozaki
authors.forename: Naoji
authors.initials: N
authors.lastname: Fujishiro
authors.forename: Kazuo
authors.initials: K
authors.lastname: Takeda
authors.forename: Issei
authors.initials: I
authors.lastname: Imanaga
authors.forename: Glenn D
authors.initials: GD
authors.lastname: Prestwich
authors.forename: Masumi
authors.initials: M
authors.lastname: Inoue
mesh_terms: D000313:Adrenal Medulla / Q000187:drug effects / Q000201:enzymology*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology; D019439:Chromaffin Cells / Q000187:drug effects / Q000201:enzymology*; D006168:Guinea Pigs; D007527:Isoenzymes / Q000737:chemistry / Q000502:physiology; D010042:Ouabain / Q000494:pharmacology; D021122:Protein Subunits / Q000737:chemistry* / Q000502:physiology*; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry* / Q000502:physiology*
chemical_list: D007527:Isoenzymes; D021122:Protein Subunits; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase