Role of cell volume variations in Na(+)-K(+)-ATPase recruitment and/or activation in cortical collecting duct.
The aim of this study was to examine whether cell volume variations could play a role in the previously reported Na(+)-K(+)-ATPase pump recruitment and/or activation induced by an increase in intracellular Na concentration (Nai) in cortical collecting ducts (CCD). Isolated CCD from kidneys of aldosterone-repleted mice were incubated in hyper-, hypo-, or isosmotic solutions with and without Na to modify Nai and cell volume independently. Nai, cell volume, and the number of basolateral pumps were measured using 22Na, image analysis, and specific [3H]ouabain binding, respectively. Ouabain-sensitive 86Rb uptake was also measured. In CCD with high Nai, pump recruitment and/or activation was observed only when an increase in tubular volume was associated with Na load. Pump recruitment and/or activation was also induced by cell swelling in the absence of Na load. Recruited and/or activated pumps display an affinity for ouabain and a specific activity (ouabain-sensitive Rb uptake per pump unit) similar to basal pumps. We conclude that 1) cell swelling is implied in the process of Nai-dependent pump recruitment and/or activation, 2) cell swelling can promote pump recruitment and/or activation independently of Na load, 3) basal and recruited and/or activated pumps probably correspond to the same Na(+)-K(+)-ATPase isoform.
Coutry
N
N
Institut National de la Santé et de la Recherche Médicale U. 246 Unité d'Enseignement et de Recherche Xavier Bichat, Paris, France.
Farman
N
N
Bonvalet
J P
JP
Blot-Chabaud
M
M
D000818:Animals; D001692:Biological Transport; D004789:Enzyme Activation; D005260:Female; D006982:Hypertonic Solutions; D007038:Hypotonic Solutions; D066298:In Vitro Techniques; D007552:Isotonic Solutions; D007672:Kidney Cortex / Q000166:cytology / Q000201:enzymology / Q000502:physiology*; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000201:enzymology / Q000502:physiology*; D007700:Kinetics; D051379:Mice; D010042:Ouabain / Q000378:metabolism; D012413:Rubidium / Q000378:metabolism; D012462:Saline Solution, Hypertonic; D000254:Sodium-Potassium-Exchanging ATPase / Q000187:drug effects / Q000378:metabolism*; D013395:Sucrose / Q000494:pharmacology; D013997:Time Factors
D006982:Hypertonic Solutions; D007038:Hypotonic Solutions; D007552:Isotonic Solutions; D012462:Saline Solution, Hypertonic; D013395:Sucrose; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium