The Stimulation of Na+, K+-ATPase Activity in the Medulla of the Rat Kidney by [arginine] Vasopressin and Its Analogues

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Abstract
Total and Na+,K+-ATPase activities were measured in sections (10 .mu.m thick) from blocks of rat kidney cultured for 5 h at 37.degree. C, pH 7.5, in Glasgow Eagle''s Minimum Essential Medium. Synthetic [arginine]vasopressin ([Arg]VP) stimulated ATPase activity in the thick tubular cells of the renal outer medulla over the concentration range 0.01-10 fmol/l, but failed to affect ATPase activity in the proximal and distal convoluted tubules of the cortex. The increase in medullary total ATPase activity induced by [Arg]VP and its analogs was wholly due to stimulation of Na+,K+-ATPase activity. Stimulation of medullary ATPase activity was blocked by [Arg]VP antiserum. The [Arg]VP analogs desmopressin, [lysine]vasopressin, [arginine]vasotocin and oxytocin stimulated medullary Na+,K+-ATPase activity, the 3 last-named analogs being considerably less potent than [Arg]VP.