EVIDENCE FOR ADRENALINE IN ADRENERGIC NEURONES

Abstract

Extracts of adrenergic fibers, whether from mesenteric nerves or from an organ containing such fibers (e.g., the heart), are like adrenaline in raising blood pressure; in being sensitized by cocaine; in causing a fall of blood pressure after ergotoxine; in producing a dilatation of the pupil; a retraction of the nictitating membrane and a relaxation of the non-pregnant cat uterus; in making the frog heart beat more rapidly and more vigorously; and in responding to a specific chemical test for adrenaline. Though extracts of liver blood vessels may have mixed effects on arterial pressure an adrenaline-like pressor action predominates; an adrenaline-like action is also demonstrable on the iris and on the nictitating membrane. Liver pulp (which doubtless contains some small vascular twigs) may produce a pure fall of pressure, have a slight mixed effect or be almost inactive. If cut hepatic nerves have degenerated, extracts of the vessels or the pulp cause a pressure fall. Extracts of uterine or intestinal muscle have mixed or depressive effects on blood pressure, and, like extracts of liver vessels and pulp, have a contractile influence on the non-pregnant uterus. Mixed and anomalous actions of the extracts are attributed to peculiar dialysates from the tissues mentioned, that act oppositely to adrenaline. Extracts of vagus nerves and skeletal muscle, and also of the heart in which sympathetic fibers have degenerated produce no distinctive adrenaline-like effects on blood pressure or iris. From these observations and those reported in the previous paper (Lissak, 1939) it is inferred adrenaline is distributed throughout adrenergic neurones. The relation of these results to the differences between adrenaline and sympathin is discussed. The results are consistent witii the view that adrenaline is liberated at the endings of adrenergic fibers, and that sympathin, which escapes from the stimulated region into the blood stream, is this adrenaline modified in the affected cells. The evidence that the parenchymal cells of the liver do not receive sympathetic fibers is considered in relation to the effect of adrenaline upon them.