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This Article Full Text Full Text (PDF) All Versions of this Article: 288/6/R1598    most recent 00741.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Veillette, P. A. Articles by Young, G. Search for Related Content PubMed PubMed Citation Articles by Veillette, P. A. Articles by Young, G.

COMPARATIVE AND EVOLUTIONARY PHYSIOLOGY

Tissue culture of sockeye salmon intestine: functional response of Na⁺-K⁺-ATPase to cortisol

¹Department of Zoology, University of Otago, Dunedin, New Zealand; and ²School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington

Submitted 2 November 2004 ; accepted in final form 26 January 2005

A method to culture tissue explants of the intestine from freshwater-adapted sockeye salmon (Oncorhynchus nerka) was developed to assess possible direct effects of cortisol on Na⁺-K⁺-ATPase activity. As judged by several criteria, explants from pyloric ceca and the posterior region of the intestine remained viable during short-term (6-day) culture, although Na⁺-K⁺-ATPase activity declined and basolateral components of the enterocytes were observed to be partially degraded. Addition of cortisol to the culture medium maintained Na⁺-K⁺-ATPase activity (over 2–12 days) above that of control explants and, in some cases, was similar to levels before culture. The response to cortisol was dose dependent (0.001–10 µg/ml). Within the physiological range, the response was specific for cortisol and showed the following hierarchy: dexamethasone cortisol > 11-deoxycortisol > cortisone. Insulin maintained Na⁺-K⁺-ATPase activity over controls in explants of ceca but not posterior intestine. To compare in vivo and in vitro responses, slow-release implants of cortisol (50 µg/g) were administered to salmon for 7 days. This treatment elevated plasma cortisol levels and stimulated Na⁺-K⁺-ATPase activity in both intestinal regions. The results demonstrate that the teleost intestine is a direct target of cortisol, this corticosteroid protects in vitro functionality of Na⁺-K⁺-ATPase, and explants retain cortisol responsiveness during short-term culture.

teleost; Oncorhynchus nerka; osmoregulation; pyloric ceca

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