Cold- and ouabain-resistance of renal Na,K-ATPase in cold-exposed and hibernating jerboas (Jaculus orientalis).
The temperature dependence and the ouabain sensitivity of Na,K-ATPase was examined in the nephron of normal, cold-exposed, and hibernating jerboas. The transport and hydrolytic activity of renal Na,K-ATPase displayed similar temperature dependence in rats and normal jerboas. Cold-resistance of Na,K-ATPase appeared in cold-exposed jerboas and further increased during hibernation. Three subpopulations of Na,K-ATPase displaying very high (Ki approximately 10(-13) M), high (Ki approximately 10(-9) M) and low sensitivity to ouabain (Ki approximately 10(-6) M) were detected in the thick ascending limb and collecting duct of jerboas. In thick ascending limbs, the subpopulation of very high sensitivity to ouabain disappeared in cold-exposed animals, which accounted for the previously reported decrease in Na,K-ATPase activity. In collecting ducts of cold-exposed animals, the subpopulation of very high sensitivity to ouabain also disappeared, but the resulting decrease in activity was overbalanced by the appearance of the subpopulation of high sensitivity.
Bennis
C
C
Laboratoire de Physiologie Animale, Faculté des Sciences, Rabat, Morocco.
Cheval
L
L
Buffin-Meyer
B
B
Younes-Ibrahim
M
M
Barlet-Bas
C
C
Marsy
S
S
Doucet
A
A
D000818:Animals; D003080:Cold Temperature; D004305:Dose-Response Relationship, Drug; D005260:Female; D007668:Kidney / Q000187:drug effects*; D008297:Male; D010042:Ouabain / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D000254:Sodium-Potassium-Exchanging ATPase / Q000187:drug effects*
D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase