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

Am J Physiol Regul Integr Comp Physiol. 2005 Jun;288(6):R1598-605. doi: 10.1152/ajpregu.00741.2004. Epub 2005 Feb 3.

Abstract

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.

MeSH terms

  • Animals
  • Anti-Inflammatory Agents / pharmacology
  • Dexamethasone / pharmacology
  • Drug Implants
  • Hydrocortisone / administration & dosage
  • Hydrocortisone / blood
  • Hydrocortisone / pharmacology*
  • Hypoglycemic Agents / pharmacology
  • Insulin / pharmacology
  • Intestinal Absorption / drug effects
  • Intestinal Mucosa / anatomy & histology
  • Intestinal Mucosa / enzymology
  • Intestines / anatomy & histology
  • Intestines / drug effects
  • Intestines / enzymology*
  • Kinetics
  • Microscopy, Electron, Transmission
  • Proteins / metabolism
  • Salmon / physiology*
  • Sodium / metabolism
  • Sodium-Potassium-Exchanging ATPase / biosynthesis*
  • Tissue Culture Techniques

Substances

  • Anti-Inflammatory Agents
  • Drug Implants
  • Hypoglycemic Agents
  • Insulin
  • Proteins
  • Dexamethasone
  • Sodium
  • Sodium-Potassium-Exchanging ATPase
  • Hydrocortisone