Vascular Action of Fresh Urine and Extracts Thereof

Abstract

Human urine and extracts of urine have been known for some time to contain both pressor and depressor substances. 1 Attempts have been made to associate them with the presence of arterial hypertension with small success. Since the properties of these substances are little known, we have undertaken a study of them.

Cats anesthetized with ethyl urethane (7–10 cc. of a 25% solution given subcutaneously) or ether were employed as test animals. Blood pressure was recorded from the femoral artery and the vagus nerves were severed. Injections of the warmed fluid were made into a femoral vein. Forty-one animals have been employed for the experiments.

Injections of 5 cc. of fresh normal urine usually produced elevation of blood pressure of from 6 to 20 mm. of Hg. Boiling the urine for 1–3 minutes did not affect the pressor action, nor did preliminary atropinization of the animal. Mixtures of urea and sodium chloride, or sodium acid phosphate of the same specific gravity as the urine, did not appear to duplicate the vascular action of urine.

Often the same test animal which yielded a pressor response to normal urine exhibited depression of the blood pressure on injecting the same urine at another time during the course of the experiment. Some animals exhibited only depressor responses. We have been unable to predict which response will occur, though the pressor was the more common. At times the animals became entirely refractory to urine injections. The variability of response led us to suspect that the functional intactness of the central nervous system was essential for a vascular response to be elicited. Decerebrate and pithed cats were found to be refractory to urine injections, whereas the same animals before pithing had responded actively. It appeared, then, that the vascular action of urine was not peripheral, but central.