The effect of sodium and angiotensin-converting enzyme inhibition on the classic circulating renin-angiotensin system in autosomal-dominant polycystic kidney disease patients

Background It has been suggested that inappropriate stimulation of the renin-angiotensin system (RAS) is responsible for the increase in blood pressure that occurs in autosomal-dominant polycystic kidney disease (ADPKD) before the development of renal failure. However, the interpretation of previous studies in ADPKD patients is confounded by inadequate matching with control populations for blood pressure and renal function, or failure to control the sodium intake of participants. Methods A double-blind, placebo-controlled study of two different sodium intakes (350 and 50 mmol/day for 5 days) in a group of 11 hypertensive ADPKD patients and eight matched control subjects with essential hypertension. In addition, blood pressure and hormonal responses were measured after the administration of the angiotensin-converting enzyme inhibitor enalapril for 3 days. Results Blood pressure and hormonal responses of the RAS after a reduction in sodium intake and after the administration of enalapril were identical in ADPKD patients and controls. Conclusions Activation of the classic circulating RAS is no greater in hypertensive ADPKD patients than in individuals with essential hypertension.