1. The adrenal response to a reduction in extracellular fluid volume (ECFV), sodium depletion, intravenous adrenocorticotrophic hormone (ACTH) and angiotensin II was assessed from changes in plasma aldosterone and plasma cortisol in eleven nephrectomized patients. Five patients were also studied before nephrectomy and six after successful renal transplantation.
2. Before nephrectomy, the resting concentrations of plasma aldosterone were usually raised. In the three patients out of five tested, the response to intravenous ACTH was marked. In two out of four patients, there was a good response to angiotensin II infusion. In one of two patients, there was a good response to a reduction in ECFV and sodium depletion.
3. After nephrectomy, the resting concentrations of plasma aldosterone were negligible or uniformly reduced and the response to ECFV reduction, sodium depletion, ACTH and angiotensin II was universally poor.
4. In all cases there was a normal plasma cortisol response to ACTH.
5. After renal transplantation in six patients, the four to whom an infusion of angiotensin II was given showed a return to a normal aldosterone response and all six showed a normal response to ACTH.
6. No clear correlation was shown between resting concentrations of plasma aldosterone and plasma potassium after nephrectomy.
7. It was concluded that the kidney, through the renin-angiotensin system, may play its main part by sensitizing the zona glomerulosa to other stimuli, but an alternative kidney-dependent mechanism cannot be excluded.