Studies of plasma renin activity in coarctation of the aorta.

Experimental and clinical studies were performed to assess the role of the renin-angiotensin system in producing hypertension in coarctation of the aorta. Basal and stimulated peripheral plasma renin activity were determined in the canine model and in four patients with coarctation. The animal studies showed no significant elevation of peripheral plasma renin activity (PPRA), and no increase in the response of PPRA to stimuli. The human studies showed a significant elevation in the response to PPRA to postural change and to exercise in three of four patients with coarctation, as compared to the same patients after correction of the coarctation. It is concluded that hyperactivity of the renin-angiotensin system is not the primary cause in coarctation hypertension in dog or man. It is nonetheless probable that the renin-angiotensin system has a role in coarctation hypertension, and further studies will be necessary to determine its place.