Cell volume-sensitive Na+-ATPase activity in rat kidney cortex cell membranes.
A ouabain-insensitive, K+-independent, sodium pump, has been demonstrated in guinea-pig and rat kidney proximal tubular cells. This pump is thought to be distinct from the ouabain-sensitive Na+/K+ pump. We present evidence here indicating the modulation of the biochemical expression of the Na+ pump, i.e. the ouabain-insensitive Na+-ATPase, by the cell volume in rat kidney proximal tubular cells. Thus, basolateral plasma membranes from swollen cells show a ouabain-insensitive Na+-ATPase activity 10-times higher than that in membranes from control cells. If the swollen cells recover their volume, the activity decreases ten times to control values. The ouabain-sensitive Na+/K+-ATPase is not affected by changes in the cell volume.
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Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela.
Duque
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Marín
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D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D027682:Cation Transport Proteins; D002462:Cell Membrane / Q000201:enzymology; D004789:Enzyme Activation; D066298:In Vitro Techniques; D007672:Kidney Cortex / Q000201:enzymology*; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000502:physiology; D014882:Water-Electrolyte Balance
D027682:Cation Transport Proteins; D010042:Ouabain; D012964:Sodium; D000251:Adenosine Triphosphatases; C021838:sodium-translocating ATPase