Effect of insulin on Na+,K(+)-ATPase in rat collecting duct.
J Physiol
; 488 ( Pt 1): 171-80, 1995 Oct 01.
Article
em En
| MEDLINE
| ID: mdl-8568653
ABSTRACT
1. The collecting duct is involved in the whole antinatriuretic effect of insulin, as indicated in vitro by the stimulatory effect of the hormone on ouabain-sensitive 86Rb+ uptake. Since Na+,K(+)-ATPase drives Na+ reabsorption, the contribution of the Na+ pump to the effect of insulin was investigated in rat isolated cortical and outer medullary collecting duct. 2. Insulin enhanced ouabain-sensitive 86Rb+ uptake in the absence, as well as in the presence, of either 5 x 10(-4) M amiloride or 10(-3) M hydrochlorothiazide (HCT). Maximal ouabain-sensitive 86Rb+ uptake, measured in Na(+)-loaded tubules, was also enhanced by insulin. The insulin effect persisted both in the absence of external Na+, when the Na+,K(+)-ATPase operates in a Rb(+)-Rb+ exchange mode, and in tubules depolarized by a high external concentration (20 mM) of Rb+ or by addition of 3 mM Ba2+. 3. Insulin treatment did not alter the intracellular Na and K concentrations, the specific binding of [3H]ouabain measured in intact tubules, or the hydrolytic activity of Na+,K(+)-ATPase measured after permeabilization of the tubule cells. 4. In conclusion, in the rat collecting duct, insulin increased Na+,K(+)-ATPase-mediated cation transport independently of Na+ availability, membrane potential and recruitment of pump units. The effect of insulin was lost after cell permeabilization, suggesting the presence of a cytosolic factor which controls the turnover of Na+,K(+)-ATPase.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
ATPase Trocadora de Sódio-Potássio
/
Insulina
/
Túbulos Renais Coletores
Limite:
Animals
Idioma:
En
Revista:
J Physiol
Ano de publicação:
1995
Tipo de documento:
Article
País de afiliação:
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