Tissue culture of sockeye salmon intestine: functional response of Na+-K+-ATPase to cortisol.
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 microg/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 microg/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.
Veillette
Philip A
PA
Department of Zoology, University of Otago, Dunedin, New Zealand. pveillette@gso.uri.edu
Young
Graham
G
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D004343:Drug Implants; D006854:Hydrocortisone / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D007408:Intestinal Absorption / Q000187:drug effects; D007413:Intestinal Mucosa / Q000033:anatomy & histology / Q000201:enzymology; D007422:Intestines / Q000033:anatomy & histology / Q000187:drug effects / Q000201:enzymology*; D007700:Kinetics; D046529:Microscopy, Electron, Transmission; D011506:Proteins / Q000378:metabolism; D012474:Salmon / Q000502:physiology*; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000096:biosynthesis*; D046509:Tissue Culture Techniques
D000893:Anti-Inflammatory Agents; D004343:Drug Implants; D007004:Hypoglycemic Agents; D007328:Insulin; D011506:Proteins; D003907:Dexamethasone; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D006854:Hydrocortisone