The Effect of Mineralocorticoid Deficiency on Renal Concentrating and Diluting Capacity

Abstract

Summary

To examine the effect of min-eralocorticoid deficiency on sodium transport by the ascending limb of the loop of Henle, free water clearance and reabsorption were measured in the same six dogs under conditions of aldosterone deficiency and mineralocorticoid sufficiency. Aldosterone deficiency was induced by bilateral adrenalectomy with dexamethasone replacement. ^cH₂O/100 ml GFR ranged from 4.0 to 19.5 in the aldosterone deficient dogs and 4.5-18.6 in the mineralocorticoid sufficient dogs. ^cH₂O/100 ml GFR plotted against V/100 ml GFR showed no significant difference between the two groups. ^TcH₂O/100 ml GFR ranged from 1.2 to 6.5 in the mineralocorticoid sufficient group and 2.4-8.5 in the aldosterone deficient group. ^TcH₂O/100 GFR plotted against ^cOsm/100 ml GFR revealed no significant difference between the two groups. Maximal urine concentration in the mineralocorticoid sufficient group was 1356 mOsm/kg ± 254 (SD) and 1386 mOsm/kg ± 331 (SD) for the aldosterone deficient group; the difference is not significant. This study failed to demonstrate any effect of aldosterone deficiency on renal concentrating and diluting capacity and thus provides inferential evidence against an effect of aldosterone on ascending limb sodium reabsorption.