Low-dose glucocorticoids maintain Na-H exchange in distal colon of adrenalectomized rats
| Autor: | C. P. Bastl, M. Mendez, E. J. Cragoe, G. Schulman, L. Bressler |
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| Rok vydání: | 1991 |
| Předmět: |
medicine.medical_specialty
Sodium-Hydrogen Exchangers Physiology Colon medicine.medical_treatment Antiporter In Vitro Techniques Dexamethasone Amiloride Chlorides In vivo Reference Values Internal medicine medicine Animals Intestinal Mucosa Aldosterone Ion transporter Chemistry Adrenalectomy Sodium Rectum Biological Transport Muscle Smooth Hydrogen-Ion Concentration Rats Endocrinology Intestinal Absorption Carrier Proteins Perfusion Glucocorticoid medicine.drug |
| Zdroj: | The American journal of physiology. 261(3 Pt 2) |
| ISSN: | 0002-9513 |
| Popis: | With in vivo perfusion we demonstrated that physiological doses of glucocorticoids restore Na and Cl absorption in adrenalectomized rat colon. The absorption is spironolactone and amiloride resistant and is inhibited by the Na-H inhibitor, 5-(N-ethyl-N-isopropyl)amiloride (EIPA), suggesting that glucocorticoids modulate Na-H antiport. The present in vitro study examines pathways mediated by glucocorticoids in adrenalectomized rat distal colon and rectum. In vivo administration of 2.5 micrograms/100 g body wt dexamethasone did not alter serosal-to-mucosal flux or tissue electrical parameters but restored mucosal-to-serosal flux and net Na and Cl absorption within 2–3 h of administration to levels found in intact rat colon. Transport was not inhibited by 10(-5) M amiloride but was eliminated by 10(-5) M EIPA. After 26 h of dexamethasone, an amiloride-resistant short-circuit current was stimulated, accompanied by increased residual ion flux in rectum, but not distal colon, suggesting that a delayed or secondary effect of glucocorticoids is stimulation of electrogenic anion secretion. Thus adrenalectomy reduces net ion flux in distal colon by its effect on electroneutral mucosal-to-serosal NaCl flux. Small doses of glucocorticoids completely ameliorate this effect via stimulation of the Na-H antiport. Glucocorticoids maintain basal electroneutral NaCl absorption in distal rat colon. |
| Databáze: | OpenAIRE |
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