Avian colonic ion transport: effects of corticosterone and dexamethasone

1. Corticosterone, a natural corticosteroid hormone in birds, when injected into domestic fowl (Gallus domesticus) (2000 micrograms.kg-1, 4-5 h before experiment) increases both the basal Isc (short-circuit current) and amiloride-sensitive Isc as well as the PD across the colon in vitro. Dexamethaso...

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Bibliographic Details
Published in:Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology Biochemical, systemic, and environmental physiology, 1989-01, Vol.159 (2), p.131-138
Main Authors: GRUBB, B. R, BENTLEY, P. J
Format: Article
Language:English
Subjects:
Amiloride - pharmacology
Animals
Biological and medical sciences
Biological Transport, Active - drug effects
Chickens
Chlorides - metabolism
colon
Colon - drug effects
Colon - metabolism
corticosterone
Corticosterone - pharmacology
dexamethasone
Dexamethasone - pharmacology
Electrophysiology
Fundamental and applied biological sciences. Psychology
Intestine. Mesentery
Ions
Potassium - metabolism
Sodium - metabolism
Vertebrates: digestive system
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Summary:1. Corticosterone, a natural corticosteroid hormone in birds, when injected into domestic fowl (Gallus domesticus) (2000 micrograms.kg-1, 4-5 h before experiment) increases both the basal Isc (short-circuit current) and amiloride-sensitive Isc as well as the PD across the colon in vitro. Dexamethasone, a synthetic analogue (650 micrograms.kg-1, 4-5 h before experiment) also increases the basal and amiloride-sensitive Isc as well as PD in these preparations. 2. In marked contrast, longer term injection or infusion of dexamethasone (650 micrograms.kg-1) for 3 or more days caused a decline in basal Isc and PD (the PD often reversed with the serosal side becoming electronegative) and a drop in resistance. However in these preparations, the amiloride-sensitive Isc was significantly elevated which could be accounted for by an increase in net Na flux. 3. No significant change occurs in net flux of Cl or K although unidirectional fluxes in both directions were increased for both ions in birds given dexamethasone for 3 days. 4. A disparity between the basal Isc and the amiloride-sensitive Isc appeared in these preparations from dexamethasone injected birds reflecting the transport of other ions, possibly HCO3- or H+. The possible role of corticosterone in mineral metabolism of birds is discussed.
ISSN:0174-1578
1432-136X
DOI:10.1007/BF00691733