Nitroprusside and the Treatment of Hypertension

Abstract

…2. Intravenously injected nitroprusside is strongly hypotensive without producing tachyphylaxis. Adrenergic blocking agents and surgical ablation of portions of the central nervous system failed to abolish its action…. Dogs with experimental neurogenic hypertension are more sensitive than renal hypertensive or normotensive dogs to the depressor effect of intravenous nitroprusside. 3. Nitroprusside is moderately vasodilator in perfused kidneys of dogs and strongly dilator in perfused hind legs. In normal, conscious dogs it caused slight increase in renal blood flow and decrease in vascular resistance with no effect on the maximal tubular excretory capacity for para-aminohippurate (TmPAH) OR the maximal tubular capacity for reabsorption of glucose (TmG), when infused intravenously. A dog with neurogenic hypertension, in contrast with those with renal hypertension, exhibited large decreases in both arterial pressure and renal resistance…. 4. Moderately depressor doses induce renal vasodilatation in hypertensive patients which is roughly equivalent to the decrease of pressure. It does not increase renal blood flow appreciably nor decrease glomerular filtration conspicuously…. 7. Hypertensive patients are more sensitive to the hypotensive action of intravenously administered nitroprusside than normotensive subjects. Chronic treatment with hydralazine or hexamethonium or single doses seems to increase this sensitivity. 8. Constant infusion of nitroprusside into patients with hypertensive encephalopathy has kept the arterial pressure at normal levels as long as 14 days with complete disappearance of the signs and symptoms. No deleterious effects from such prolonged administration have been noted and the rapidity of its therapeutic effects has been striking. 1