Effects of chronic hypoxia on electrogenic transport and transport-related oxygen consumption in rat distal colon.
The distal colon epithelium of rats submitted to chronic hypoxia shows higher short-circuit current (Isc) which, unlike non-hypoxic rat epithelium, has an amiloride-sensitive component despite low serum aldosterone levels. Isc and oxygen consumption (QO2) were simultaneously measured in mucosae from rats submitted to 0.5 atm for 10 days and from control rats in a modified Ussing chamber. Hypoxia increased Isc but not QO2. The slope of the regression line between Isc and QO2 reduction after ouabain addition was decreased in epithelia from hypoxic rats (P = 0.03). Chloride secretion blockade reduced Isc and QO2 in both groups, while sodium channel blockade did so only in the hypoxic group. Dual blockade in hypoxic rat epithelia caused correlated (P = 0.0025) additive decreases in Isc and QO2. Presented results suggest that chronic hypoxia induces an improved coupling between QO2 and electrogenic ion transport, and electrogenic sodium absorption despite low aldosterone levels.
Cincunegui
Liliana M
LM
Area de Física Biológica, Departamento de Morfología y Fisiología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Casilla de Correo 33, Mendoza 5500, Argentina.
Ituarte
Leonor M I
LM
Viera
Teresa B
TB
Ibañez
Jorge E
JE
Carra
Graciela E
GE
Saldeña
Teobaldo A
TA
Saravi
Fernando D
FD
D000450:Aldosterone / Q000097:blood; D000704:Analysis of Variance; D000818:Animals; D001274:Atmospheric Pressure; D002908:Chronic Disease; D003106:Colon / Q000378:metabolism*; D004594:Electrophysiology; D000860:Hypoxia / Q000503:physiopathology*; D017136:Ion Transport / Q000502:physiology*; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism*
D000450:Aldosterone; D012964:Sodium