Observations on Hemodynamic Effect of Epinephrine in Unanesthetized Dog.

Abstract

The recent study by Luckhardt and Koppanyi 1 on the hemodynamic action of subcutaneously injected epinephrine shows in a most striking way the influence of anesthetics upon the vascular response to this agent. They found that a pressor response was not readily obtained in animals under barlntal after massage of the injected area, while good responses were obtained under paraldehyde. Ether was found to diminish or entirely suppress the pressor response, when administered by inhalation, and, when injected intravenously in small doses. Morphine apparently had no depressing effect. It appears, therefore, that anestheties may have an effect upon the vascular response to epinephrine per se. or, by altering the acidbase balance of the blood. 2 As most of the previous work 3 in determining the minimal effective amount of epinephrine in altering the blood pressure has been done on anesthetized animals, or animals with brain and cord pithed, it seemed necessary to restudy this problem on the unanesthetized animal.

Under ether anesthesia animals were prepared by transplanting the carotid artery externally to the skin. Such animals are suitable for use within 5 or 6 hours, or can be used after several days. They were then placed on the table and a carotid cannula inserted. Some animals required small doses of morphine for the procedure, others not. Injections were made into the saphenous vein from a Woodyatt pump. Pure crystalline adrenalin was received from Parke Davis and Co., and solutions were made in slightly acidified distilled water, fresh for each experiment. We found a marked deterioration in the higher dilutions if made with Ringer's solution. Control injections of distilled water were made frequently. The injections were made as a rule for a period of 2 minutes, and not more than 5 to 8 cc. of fluid injected in this time.