Regulation of renal Na+-K+-ATPase in the rat by adrenal steroids.
The effects of single and multiple injections of aldosterone and dexamethasone on renal Na+-K+-ATPase, in vitro renal gluconeogenesis, and urinary electrolyte excretion were examined in adrenalectomized rats in a dose-dependent manner. Single maximal and supramaximal doses of aldosterone (defined by the effect of electrolyte excretion) had no effect on Na+-K+-ATPase or gluconeogenesis. By contrast, a single administration of dexamethasone (in a dose range that increased fasting blood sugar, stimulated renal gluconeogenesis, and had no mineralocorticoid effects) yielded clear-cut activation of Na+-K+-ATPase. Multiple submaximal doses of dexamethasone produced quantitatively similar stimulation of Na+-K+-ATPase and gluconeogenesis. Multiple supramaximal doses of aldosterone stimulated Na+-K+-ATPase and gluconeogenesis, but maximal and submaximal doses of the hormone were without effect. Aldosterone had no effect on hepatic Na+-K+-ATPase or gluconeogenesis. These results suggest that activation of renal Na+-K+-ATPase can be considered a putative glucocorticoid (not mineralocorticoid) effect. Renal Na+-K+-ATPase activation by chronic aldosterone treatment may be mediated by glucocorticoid receptor sites and, hence, may not represent a genuine mineralocorticoid effect.
D000305:Adrenal Cortex Hormones / Q000502:physiology*; D000450:Aldosterone / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D003907:Dexamethasone / Q000008:administration & dosage / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004573:Electrolytes / Q000652:urine; D005260:Female; D005943:Gluconeogenesis / Q000187:drug effects; D007668:Kidney / Q000201:enzymology* / Q000378:metabolism; D008099:Liver / Q000201:enzymology / Q000378:metabolism; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D000305:Adrenal Cortex Hormones; D001786:Blood Glucose; D004573:Electrolytes; D000450:Aldosterone; D003907:Dexamethasone; D000254:Sodium-Potassium-Exchanging ATPase