title: Effect of insulin on Na+,K(+)-ATPase in rat collecting duct.
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.
authors.affiliation: Division de Néphrologie, Hôpital Cantonal Universitaire, Genève, Switzerland.
authors.forename: E
authors.initials: E
authors.lastname: Féraille
authors.forename: M
authors.initials: M
authors.lastname: Rousselot
authors.forename: R
authors.initials: R
authors.lastname: Rajerison
authors.forename: H
authors.initials: H
authors.lastname: Favre
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D006868:Hydrolysis; D007328:Insulin / Q000494:pharmacology*; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D009399:Nephrons / Q000187:drug effects / Q000201:enzymology; D010042:Ouabain / Q000378:metabolism / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012414:Rubidium Radioisotopes / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000187:drug effects / Q000378:metabolism*; D014316:Tritium
chemical_list: D007328:Insulin; D012414:Rubidium Radioisotopes; D014316:Tritium; D010042:Ouabain; D000255:Adenosine Triphosphate; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium