Author(s): El Mernissi G, Doucet A
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Abstract The short-term effect of one single injection of aldosterone on the renal sodium transport on one hand, and the Na-K-ATPase activity on the other hand, was studied in chronic adrenalectomized rats. Sodium transport was estimated by clearances, and Na-K-ATPase was measured in microdissected fragments of the nephron, according to our microtechnique previously described. Five to eight days after adrenalectomy, only 30\% of the initial enzyme activity was recovered in the cortical collecting tubule (CCT). Administration of aldosterone completely restored the ATP-ase activity within three hours. Adrenalectomy also curtailed by 20-45\% the activity of other nephron segments but aldosterone had no stimulatory effect on them. Sodium-reabsorption also increased after the hormone injection, following the same time (0.5 less than t1/2 less than 1 h) and dose dependencies (0.8 less than K1/2 less than 0.9 micrograms/kg) as those observed for the enzyme activity in the CCT. It is concluded that the short-term stimulation of Na-K-ATPase in the collecting tubule, after an acute administration of aldosterone, may be responsible for the simultaneous increase in sodium transport.
This article was published in Pflugers Arch
and referenced in Journal of Steroids & Hormonal Science