Experiments on the Supposed Relation of Epinephrine Secretion to Hypertension

Abstract

Cannon and de la Paz 1 suggested that, in emotional excitement, “some of the adrenal secretion set free by nervous stimulation returns to the glands in the blood stream, and, within limits, stimulates them to further activity.” If this occurs, it is conceivable that it might play a significant rôle in the production of a persistent elevation of blood pressure. However, such an “autogenous continuance of adrenal secretion,” assumed to be important as an emergency function, would at the same time constitute a serious potential menace.

We made quantitative determinations of the rate of epinephrine secretion from the adrenals in dogs after intravenous administration of epinephrine. Ten to 500 times the average amount of epinephrine ordinarily secreted per minute (Stewart and Rogoff 2 ) was injected. Epinephrine concentrations were determined with segments of rabbits' intestine. Some of the results were confirmed by the method described by Rogoff. 3 In some experiments the epinephrine was administered at a constant rate, in others it was given in a single injection to simulate an “outburst” from the adrenals as is alleged to occur during emotional excitement. Injection of 0.002 mg. per kg. body weight per minute caused an elevation of blood pressure in anesthetized dogs; striking effects were produced by the larger doses.

Constant injection of epinephrine in doses equal to 10, 20, and 50 times the average normal rate of liberation from the adrenals, did not influence the rate of epinephrine secretion from the glands; nor did such quantities measurably alter the epinephrine concentration in the adrenal vein blood. Similar results were obtained with doses up to 500 times the normal output although in some cases the epinephrine concentration in the adrenal vein blood was increased by the circulating epinephrine.