PHYSIOLOGY OF EPINEPHRINE 107 



that it exerts a continuous tonic influence on the structures 

 under sympathetic control, particularly upon the blood vessels. 

 That the vascular tone is not sustained by a steady discharge 

 of epinephrine is demonstrated by the fact that ligation of the 

 adrenal vessels, cutting the splanchnic nerves, or otherwise 

 removing the supply of epinephrine has no effect upon the 

 blood pressure. 307 Adrenalectomized animals may be main- 

 tained in perfect health indefinitely without the administra- 

 tion of epinephrine. Since small doses of epinephrine have a 

 depressor effect one would, as a matter of fact, expect the 

 minute quantity normally secreted into the blood stream to 

 cause a drop in blood pressure rather than any rise. 222 



The view advanced by Elliott 177 that epinephrine is neces- 

 sary for maintaining normal sympathetic impulses has also 

 been thoroughly disproven. The response to sympathetic 

 impulses remains unimpaired in adrenalectomized animals, nor 

 does the infusion of epinephrine facilitate the passage of such 

 impulses. 269 



Gley and Quinquaud 224 in a series of papers have also vigor- 

 ously attacked the tonus theory of medullary function. They 

 demonstrated that exclusion of the adrenals from the circula- 

 tion did not influence the effects of vagal, depressor, or ac- 

 celerator stimulation on the heart rate; nor did it influence the 

 effects of splanchnic stimulation or asphyxia on the blood 

 pressure. 



The view that epinephrine exerts a continuous effect on the 

 heart and blood vessels has been more recently advocated by 

 Tournade and Chabrol, 630 and Heymans. 297 The first men- 

 tioned authors 634 found that the blood pressure of an adrenal- 

 ectomized dog under choloralose anesthesia rose when its 

 jugular vein was anastomosed with the right adrenal vein of a 

 second dog whose adrenals were intact. If the left adrenal of 

 the second dog was now excised and the right splanchnic nerve 

 cut, thus cutting off the supply of epinephrine, the blood 

 pressure of the first animal dropped from 160 to 100 mms. of 

 Hg. 



