Angiotensin blockade: its clinical significance.

An understanding of the possible role of excessive angiotensin II activity in the pathogenesis of hypertension in every patient is therapeutically desirable, but it is frustrated by the lack of complete reliability of peripheral plasma measurements of renin activity. Observation of a clear-cut, supranormal decrease in blood pressure during the intravenous infusion of the angiotensin II antagonist, saralasin, has provided a far more reliable indication of the presence of an angiotensinogenic component in the hypertension. There is convincing evidence, however, that the presence of sodium-overload may prevent a decrease in blood pressure during saralasin infusion in persons known to have angiotensinogenic hypertension and that saralasin may cause a slight decrease in the blood pressure of normal subjects after natriuresis. For these reasons, it is important to study hypotensive responses to saralasin under standardized conditions after the administration of a potent diuretic and to compare the observations with those made on normal subjects under identical circumstances. This angiotensin antagonist may be used in the therapy of malignant or advanced hypertension and as an aid to therapeutic decisions in hypertensive patients who have known renal diseases, are taking oral contraceptives or have had severe trauma to the area of the kidneys. Side effects of saralasin are limited to excessive falls in blood pressure levels, mainly when vasodilators or ganglioplegic drugs are being taken at the time of the saralasin infusion, and excessive rises in blood pressure levels, especially in hypertensive subjects with "low renin" activity during high rates of saralasin infusion or after intravenous injections of large boluses. This safe and reliable drug is a valuable tool in the investigation and therapy of hypertension.