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08:39
Murine Colitis Modeling using Dextran Sulfate Sodium (DSS)
Published on: January 19, 2010
Low-dose glucocorticoids stimulate electroneutral NaCl absorption in rat colon
C P Bastl1, G Schulman, E J Cragoe
1Department of Medicine, Temple University Health Sciences Center, Philadelphia, Pennsylvania 19140.
The American Journal of Physiology
|December 11, 1989
Summary
Glucocorticoids regulate colonic sodium (Na) and chloride (Cl) absorption through an amiloride-resistant pathway, likely the Na-H antiport. This differs from aldosterone, which induces amiloride-sensitive Na absorption.
Area of Science:
- Physiology
- Endocrinology
- Gastroenterology
Background:
- Aldosterone stimulates conductive Na absorption in the colon, which is inhibited by amiloride and spironolactone.
- Basal colonic NaCl transport is electroneutral and resistant to amiloride and spironolactone.
- Glucocorticoids may play a role in regulating basal colonic NaCl transport.
Purpose of the Study:
- To investigate the Na absorptive pathway induced by glucocorticoids in the rat colon in vivo.
- To differentiate the effects of glucocorticoids from aldosterone on colonic Na absorption.
- To identify the specific mechanism of glucocorticoid-induced Na and Cl absorption.
Main Methods:
- Administration of specific glucocorticoid doses (dexamethasone, RU26988) in vivo.
- Utilized various amiloride analogues, including the Na-H antiport inhibitor 5-N-ethyl-N-isopropylamiloride (NENIA).
- Measured Na and Cl absorption and transmural potential difference (PD) in proximal and distal colon.
Main Results:
- Glucocorticoids (dexamethasone, RU26988) stimulated Na absorption via an amiloride-resistant mechanism at low doses.
- NENIA (a Na-H antiport inhibitor) eliminated glucocorticoid-induced Na and Cl absorption without altering PD.
- NENIA did not affect aldosterone-induced transport, and resistance to NENIA developed with time in adrenal-intact animals.
Conclusions:
- Glucocorticoids induce an electroneutral Na absorptive pathway in the rat colon, potentially via the luminal Na-H antiport.
- This glucocorticoid-induced pathway is distinct from aldosterone-mediated conductive Na absorption.
- Glucocorticoids likely regulate adrenal-dependent electroneutral Na absorption in the colon.
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