THE EFFECTS OF l-EPINEPHRINE AND l-NOR-EPINEPHRINE UPON CEREBRAL CIRCULATION AND METABOLISM IN MAN 1

Abstract

Studies comparing the effects of epinephrine and nor-epinephrine, the two sympathomimetic amines which occur naturally in the mammalian body, show that these two closely related substances differ in many of their pharmacodynamic properties. The metabolic rate in man has been shown to increase after epinephrine (1, 2), whereas there is no significant change produced by nor-epinephrine (2). Systemic administration of epinephrine to man has been shown to result in a decrease in total peripheral resistance (1, 3), indicating that vasodilatation has occurred in many portions of the body; in contrast, nor-epinephrine appears to be predominantly vasoconstrictor in its action, for total peripheral resistance is increased (3).These differences may be manifestations of the specific functions which these substances perform in the body; von Euler (4) believes that nor-epinephrine is the sympathetic mediator for general purposes, while epinephrine acts as an adjuvant for more special functions, especially in regard to metabolic actions.In view of the importance of epinephrine and nor-epinephrine in physiological processes, their occurrence in pheochromocytomas, their use as therapeutic agents, and the possible relation of nor-epinephrine to essential hypertension (3), information regarding their effect on cerebral blood flow and cerebral metabolism is desirable. A preliminary report by Sensenbach, Madison, and Ochs (5) indicates that nor-epinephrine is a powerful cerebral vasoconstrictor. The animal studies upon epinephrine have yielded conflicting results (6-8). Qualitative measurements of cerebral blood flow in man by means of a thermoelectric

Autoregulation of Cerebral Blood Flow in Experimental Focal Brain Ischemia

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Significance of the Cerebrovascular Effects of Immobilization Stress in the Rabbit

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