title: Chronic hypobaric hypoxia effects on rat colon in vitro sensitivity to acute hypoxia and amiloride.
abstract: Chronic hypoxia induces many physiological changes, but little is known about its effects on colonic epithelial function. Isolated distal colon mucosa from rats under normobaric conditions and rats submitted to hypobaric hypoxia for either 4 or 10 days was studied in an Ussing chamber. After 4 days of hypoxia, there was only a 15% increase in transepithelial resistivity. However, 10-day hypoxic rats showed higher short circuit current, potential difference, and resistivity. In this group, but not in normal or 4-day hypoxic animals, amiloride dose-dependently depressed short circuit current. The response to acute hypoxia in vitro was unchanged after chronic hypoxia and was not affected by amiloride. Although the amiloride-sensitive increase in short circuit current in 10-day hypoxic rats might resemble mineralocorticoid action, resistivity was increased and serum aldosterone was very low. It is suggested that chronic hypoxia may enhance electrogenic sodium transport by an aldosterone-independent mechanism.
authors.affiliation: Departamento de Morfofisiologia, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina.
authors.forename: Fernando D
authors.initials: FD
authors.lastname: Saraví
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Chirino
authors.forename: Teobaldo A
authors.initials: TA
authors.lastname: Saldeña
authors.forename: Liliana M
authors.initials: LM
authors.lastname: Cincunegui
authors.forename: Graciela E
authors.initials: GE
authors.lastname: Carra
authors.forename: Leonor M E
authors.initials: LM
authors.lastname: Ituarte
mesh_terms: D000584:Amiloride / Q000494:pharmacology*; D000818:Animals; D001274:Atmospheric Pressure; D003106:Colon / Q000187:drug effects* / Q000503:physiopathology*; D000860:Hypoxia / Q000503:physiopathology*; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000187:drug effects / Q000503:physiopathology; D008297:Male; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000584:Amiloride