800 PHYSIOLOGY OF DIGESTION AND SECRETION. 



possess secretory nerve fibers. Abel * has succeeded in isolating a 

 substance from the gland that produces the effect on blood-pressure 

 and heart rate, and proposes for it the name epinephrin hydrate. 

 He assigns to it the formula C 10 H 13 NO 3 H 2 O and describes it as 

 a peculiar, unstable, basic body. Salts of epinephrin may be ob- 

 tained which when injected into the circulation cause the typical 

 effects produced by injection of extracts of the gland. 



The active principle of the gland has been prepared in crystalline 

 form and named adrenalin (Takamine, Aldrich); its formula is 

 given as C 9 H 13 NO 3 . This substance is much used practically in 

 minor surgical operations as a hemostatic to check the flow of blood. 

 The constriction of the blood-vessels seems to be due to a direct 

 effect upon the walls of the vessels, either upon the musculature 

 itself or upon the endings of the peripheral nerve fibers distributed 

 to these muscles. That the effect is not entirely central is indicated 

 by the fact that after destruction of the vasoconstrictor center and 

 removal of the spinal cord injection of the extracts causes a rise 

 of blood-pressure of 100 per cent, or more. Langley has called 

 attention to the peculiar fact that the action of adrenal extracts 

 or solutions of adrenalin on plain muscle resembles always the 

 effect of stimulating the sympathetic nerves supplying the same 

 tissue. It has been proposed, therefore, to use these solutions to 

 determine whether or not given vascular areas, such as those of the 

 brain or lungs, are provided with vasoconstrictor nerve fibers. 

 When adrenalin is injected into a normal animal it may have an 

 influence upon the nerve centers of the vasomotor nerves as well 

 as upon the peripheral endings. Meltzer f has shown that mod- 

 erate doses under such conditions may cause a dilatation, while 

 in parts whose connection with the nerve center is destroyed only 

 a constriction is obtained. Under normal conditions at least 

 these extracts when injected into the circulation soon lose their 

 effect. This fact may explain why injection of the extracts has 

 failed to give permanent relief in animals from whom the adrenals 

 had been removed or in human beings suffering from Addison's 

 disease. Bearing in mind the results obtained in the case of thy- 

 roidectomy, it has been suggested that grafts of the adrenals under 

 the skin or into the peritoneal cavity may prove more effective. 

 Results by this method have been chiefly negative, owing apparently 

 to the fact that in such grafts the medullary substance, which con- 

 tains the material that causes constriction of the blood-vessels, 

 readily undergoes atrophy and absorption, but Busch and Van 

 Bergen J report at least one successful transplantation of the adrenal 



*Abel, "Berichte d. deut. chem. Gesellschaft," 37, 368, 1904. 



t S. J. and Clara Meltzer, "American Journal of Physiology, " 9. 252, 

 1903. 



J Busch and Van Bergen. "American Journal of Physiology," 1906, xv., 

 444. 



