The stimulation of Na+, K+-ATPase activity in the medulla of the rat kidney by [arginine] vasopressin and its analogues.

Total and Na+, K+-ATPase activities have been measured in sections (10 micron thick) from blocks of rat kidney cultured for 5 h at 37 degrees 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 analogues was wholly due to stimulation of Na+, K+-ATPase activity. Stimulation of medullary ATPase activity was blocked by [Arg]VP antiserum. The [Arg]VP analogues desmopressin, [lysine]vasopressin, [arginine]vasotocin and oxytocin stimulated medullary Na+, K+-ATPase activity, the three last-named analogues being considerably less potent than [Arg]VP.