Mineralocorticoid effects on Na-K-ATPase in individual nephron segments.
A fluorometric micromethod for the assay of Na-K-ATPase was used to determine Na-K-ATPase activity in 11 segments of the rabbit nephron. The Na-K-ATPase activity was found to be highest (greater than 100 pmol.mm1-.min-1) in proximal convoluted tubules (S1), medullary thick ascending limbs, distal convoluted tubules, and connecting tubules. There was a good correlation (r = 0.94) between Na-K-ATPase activity in different segments and net Na transport previously measured by in vitro tubule perfusion. Treatment of rabbits with deoxycorticosterone (DOCA) for 8-11 days produced increases in Na-K-ATPase activity of 100 and 500% in connecting tubules and cortical collecting ducts, respectively, without significant change in other segments. Maintenance on a low sodium diet for 12-18 days was associated with a 200% increase in Na-K-ATPase activity in cortical collecting ducts only. We conclude that the Na-K-ATPase activity is stimulated by mineralocorticoids in the cortical collecting duct in association with the previously observed changes in sodium transport.
D000450:Aldosterone / Q000097:blood; D000818:Animals; D003900:Desoxycorticosterone / Q000494:pharmacology*; D004039:Diet, Sodium-Restricted; D007686:Kidney Tubules, Distal / Q000201:enzymology; D007687:Kidney Tubules, Proximal / Q000201:enzymology; D008856:Microscopy, Fluorescence; D009399:Nephrons / Q000187:drug effects / Q000201:enzymology*; D011188:Potassium / Q000097:blood; D011817:Rabbits; D012083:Renin / Q000097:blood; D012964:Sodium / Q000097:blood; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
D003900:Desoxycorticosterone; D000450:Aldosterone; D012964:Sodium; D012083:Renin; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium