Effect of NH4Cl on Plasma Aldosterone, Cortisol and Renin Activity in Supine Man

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Abstract
Plasma aldosterone, renin activity, cortisol and serum potassium were measured in six normal subjects before (control day) and during the oral administration of NH4Cl (1.9 meq/kg body weight). Blood samples were obtained with the subjects supine and fasting while in balance on a 10 meq sodium, 60 meq potassium diet. During the control day, 24 h urinary sodium excretion was 8 ± 3 (se) meq and plasma aldosterone, renin activity and cortisol followed their expected diurnal variation. Following NH4Cl (given between 0900 h and 1100 h), venous blood pH and serum bicarbonate concentrations decreased (P < 0.05 and P < 0.005, respectively) but the expected circadian decline in plasma aldosterone did not occur and the values at 1200 h and 1600 h were higher (P < 0.05 and P < 0.02, respectively) than those of the control day. There were slight but not significant increases in plasma renin activity and serum potassium concentration. These observations indicate that plasma aldosterone increases in response to NH4Cl. The observed changes may have been related to the combined effect of the slight increases in serum potassium and/or plasma renin activity. However, we can not exclude the possibility that acidosis per se, at least in part, stimulated an increased adrenal secretion of aldosterone.