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This Article Full Text Full Text (PDF) All Versions of this Article: 564/1/161    most recent jphysiol.2004.081455v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Lin, H. Articles by Inoue, M. Search for Related Content PubMed PubMed Citation Articles by Lin, H. Articles by Inoue, M.

⁴ Department of Cell and System Physiology
³ Department of Cellular and Molecular Biology, University of Occupational and Environmental Health School of Medicine, Kitakyushu 807-8555, Japan
¹ Department of Physiology, Fukuoka University School of Medicine, Fukuoka 814-0180, Japan
² Department of Medical Chemistry, University of Utah, 419 Wakara Way, Suite 205, Salt Lake City, UT 84108, USA

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 and ß subunits in rat and guinea-pig AM cells were examined using amperometry and immunological techniques. While exposure to 1 µM 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 1 subunit-like and ß3 subunit-like immunoreactive (IR) materials were distributed ubiquitously at the cell periphery, whereas 2- and ß2-like IR materials were present in restricted parts of the cell periphery. The 1 and 2 subunits were mainly immunoprecipitated from AM preparations by anti-ß3 and anti-ß2 antisera, respectively. Peripheral BODIPY-FL-InsP₃ binding sites were localized below membrane domains with 2- and ß2-like IR materials. The results indicate that in AM cells, 1ß3 isozymes of Na⁺,K⁺-ATPase were present ubiquitously in the plasma membrane, while 2ß2 isozymes were in the membrane domain closely associated with peripheral Ca²⁺ store sites. This close association of the 2ß2 isozyme with peripheral Ca²⁺ store sites may account for the facilitation of mobilization-dependent secretion in the presence of 1 µM ouabain.

(Received 16 December 2004; accepted after revision 28 January 2005; first published online 3 February 2005)
Corresponding author M. Inoue: Department of Cell and System Physiology, University of Occupational and Environmental Health, School of Medicine, Kitakyushu 807-8555, Japan. Email: minoue{at}med.uoeh-u.ac.jp