Effects of mineralocorticoids on Na+ and K+ excretion in the adrenalectomized rat.
The short-term effects (within 4 h) of low doses of intravenous aldosterone or deoxycorticosterone on potassium and sodium urinary excretion were studied by clearance techniques in 24-h adrenalectomized, anesthetized male rats. All animals were substituted with a glucocorticoid (dexamethasone; plasma concentration approximately 6 nM) to maintain normal glomerular filtration rate. The mineralocorticoid effects were studied under various conditions of sodium and potassium load. Mineralocorticoid administration uniformly resulted in antinatriuresis, starting within 30-60 min and, at the peak effect, amounting to 1-2% sodium fractional excretion. The level of antinatriuresis was directly related to the control sodium excretion before aldosterone administration. Mineralocorticoids induced a significant kaliuresis in all groups except one, the one receiving the lowest sodium load. The aldosterone-induced kaliuresis was also related to the sodium load and the control fractional sodium excretion level and was simultaneous with the beginning of the reduced sodium excretion. In control, mineralocorticoid-deprived rats, kaliuresis was not enhanced by increasing the sodium load. Control as well as mineralocorticoid-treated rats responded by an increased kaliuresis following an acute potassium load and by a decreased kaliuresis after 3 days of low potassium diet.
D000315:Adrenalectomy; D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology*; D005919:Glomerular Filtration Rate / Q000187:drug effects*; D007700:Kinetics; D008297:Male; D011188:Potassium / Q000097:blood / Q000652:urine*; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000652:urine*
D000450:Aldosterone; D003907:Dexamethasone; D012964:Sodium; D011188:Potassium