Acute inhibition of the renin-angiotensin system: interest and limits to detect surgically curable hypertension.

The acute blockade of the renin-angiotensin system has been made it possible to investigate its role in the maintenance of blood pressure and aldosterone secretion in normotensive and hypertensive subjects. The administration of saralasin or captopril and, in the near future, of renin inhibitors induces a fall in blood pressure that is variable from one subject to the other according to the sodium balance and the level of activation of the system. These blockers also decrease the angiotensin II-dependent aldosterone production and increase renin secretion according to the circulating level of angiotensin II and the functional state of adrenal and juxtaglomerular receptors. In practice the definition of an abnormal response to renin-angiotensin blockade is difficult to define precisely, but the hypotensive effect has been tentatively used for the diagnosis of renin-dependent hypertension, especially renovascular hypertension and primary hyperaldosteronism. In renal artery stenosis the most convincing results mainly concern the lateralization of an abnormal unilateral renin secretion, which is potentiated by an acute blockade of the renin-angiotensin system. The acute administration of converting enzyme inhibitor is also useful to detect the absence of decrease in plasma aldosterone, which is characteristic of a solitary tumor or of other anatomical and functional disorders of the adrenal glands.