Regulation of renal Na+-K+-ATPase in the rat: role of increased potassium transport.
The purpose of this study was to characterize the alterations in collecting tubule Na+-K+-ATPase activity produced by sustained increments in dietary potassium in the rat and to evaluate the role of aldosterone in their generation. In adrenal-intact animals, feeding a high-potassium diet (10-fold that of control) or administration of a high physiological dose of aldosterone (5 micrograms X 100 g-1 X day-1), which simulates the delivery rate of this hormone during potassium loading (both for 7 days), caused marked increments in Na+-K+-ATPase activity in the cortical collecting tubule (CCT) but had no effect on the enzyme in the inner stripe of the medullary collecting tubule (MCT). A significant increase in enzyme activity was also observed after smaller dietary potassium increments (2.5 and 5 times the control) and after 4 (but not 2) days of dietary potassium load. In adrenalectomized rats provided with physiological replacement doses of corticosterone and aldosterone (0.8 micrograms X 100 g-1 X day-1), Na+-K+-ATPase activity in both CCT and MCT was similar to that of adrenal-intact controls but remained unchanged after 7 days on the potassium-enriched (10-fold) diet. In contrast, adrenalectomized animals receiving the high physiological dose of aldosterone displayed an increase in Na+-K+-ATPase activity of CCT comparable with that of adrenal-intact animals, whereas the enzyme activity in the MCT was unaffected. In conclusion, 1) following chronic potassium loading Na+-K+-ATPase activity increases significantly in the CCT with no change in its activity in the inner stripe of the MCT.(ABSTRACT TRUNCATED AT 250 WORDS)
D000315:Adrenalectomy; D000450:Aldosterone / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport; D004032:Diet; D007684:Kidney Tubules / Q000201:enzymology*; D007685:Kidney Tubules, Collecting / Q000201:enzymology*; D008297:Male; D011188:Potassium / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013148:Spironolactone / Q000494:pharmacology
D013148:Spironolactone; D000450:Aldosterone; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium