49 METABOLISM, NUTRITION, AND DIET 



the same manner. The conclusion follows that the active principle, 

 epinephrin, specifically stimulates the sympathetic and autonomic 

 mechanisms. The point of action is the nerve endings in the peripheral 

 tissue and the reaction is sympathomimetic. 



a. The Nature of the Active Principle of the Suprarenal Gland. Early 

 workers, notably Oliver and Schafer, studied this gland - by extracts of its 

 dried tissue. Thus they stated that less than y T J-^ gram (%%-$ grain) of the 



FIG. 316. Injection of Suprarenal Extract. Effect upon the heart, limb, spleen and 

 blood-pressure, after section of cord and vagi. (Oliver and Schafer.) 



desiccated gland is sufficient to produce an effect upon the heart arid arteries 

 of an adult man. 



It is a curious fact that only extracts of the medullary portion of the gland 

 are active. It has been further shown, by Christiani and others, that if only 

 small portions of the medulla remain, the animal operated upon survives; 

 while if all the medullary substance be removed, even though large portions 

 of the cortex remain, the animal invariably dies. 



Abel has succeeded in separating the blood-pressure-raising constituent 

 of the gland extract, and calls it epinephrin, C 10 H 13 NO 3 JH 2 O. Takamine 

 isolated an active principle to which he assigned the formula C 9 H 13 NO 3 , 

 and the name adrenalin. This product is now known to be an amino- 

 alcohol with a pyrocatechin base as follows: 



