Elevated plasma renin activity in aortitis syndrome.

Plasma renin activity (PRA) was measured in 38 cases of aortitis syndrome. The values of resting peripheral vein blood PRA were 32.2 +/- 4.2 (SE) mmug/ml. These values were 3 times higher than those of normal subjects. Hypertension due to renal arterial stenosis was observed in 18 cases. Their resting PRA values were 41.2 +/- 6.0 mmug/ml, while in the remaining 20 patients without renovascular hypertension those values were 24.2 +/- 5.4 mmug/ml. The patients belonging to aortic arch type or extensive type had 2 times higher PRA values than those of abdominal type. The patients with stenosis or obstruction of common carotid arteries had significantly higher PRA values than the patients without these lesions. Hyperresponse of renin secretion to upright posture was also observed in the same patients with carotid artery stenosis. Abnormal renin release in Takayasu's arteritis disappeared after denervation of the carotid sinus nerve. The present study suggests that the unstable state of carotid sinus reflex is the main cause for the hypersecretion of renin.