Cell sodium-induced recruitment of Na(+)-K(+)-ATPase pumps in rabbit cortical collecting tubules is aldosterone-dependent.
The influence of intracellular sodium concentration ( [Na+]i) on the number of Na(+)-K(+)-ATPase pumps was examined in cortical collecting tubules (CCD) of kidneys from rabbits in different aldosterone conditions. Specific [3H]ouabain binding was measured in isolated CCD with various [Na+]i. Experiments were performed on adrenalectomized rabbits receiving only a substitutive dose of dexamethasone and on adrenalectomized rabbits replete with aldosterone. In aldosterone-replete rabbits, the number of binding sites increased linearly with [Na+]i, from 16 fmol/nl tubular volume at 15 mM Na+i to 39 fmol/nl tubular volume at 140 mM Na+i. Neither actinomycin D (5 microM) nor cycloheximide (10 microM) prevented this [Na+]i-dependent increase. In adrenalectomized rabbits, the number of ouabain-binding sites was reduced and did not increase with [Na+]i. These results are in favor of the presence of a "latent" pool of pumps in CCD, rapidly recruited under [Na+]i influence. Aldosterone appears to be required for the constitution and/or activation of this pool.
Blot-Chabaud
M
M
Departement de Biologie, Institut National de la Santé et de la Recherche Médicale U246, Gif-sur-Yvette, France.
Wanstok
F
F
Bonvalet
J P
JP
Farman
N
N
D000315:Adrenalectomy; D000450:Aldosterone / Q000097:blood / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology; D005260:Female; D007672:Kidney Cortex / Q000201:enzymology*; D007684:Kidney Tubules / Q000201:enzymology*; D007685:Kidney Tubules, Collecting / Q000201:enzymology*; D007700:Kinetics; D010042:Ouabain / Q000378:metabolism; D011485:Protein Binding; D011817:Rabbits; D012016:Reference Values; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D000450:Aldosterone; D010042:Ouabain; D003907:Dexamethasone; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase