96 MEDULLA 



based on the stimulating effect of epinephrine on oxidation in 

 Thunberg's methylene blue -muscle extract system, found the 

 peripheral venous blood of man and the rabbit to contain about 

 0.000,000,0001 mgm. of epinephrine per cc. 



THE NERVOUS CONTROL OF EPINEPHRINE SECRETION 



The rate of secretion of epinephrine has been shown to be 

 readily affected by impulses from the splanchnic nerves and 

 hence it may be assumed that these nerves normally control 

 the rate of secretion. Stimulation of the nerves to the adrenal 

 increases the rate of epinephrine secretion; sectioning the 

 nerves, abolishes the secretion. Elliott 178 showed that the 

 epinephrine store was protected against depletion by anes- 

 thesia and certain other stimulants to secretion if all the fibers 

 coming to the semilunar ganglion were cut. If the spontaneous 

 discharge of epinephrine be under nervous control, we must 

 explain Elliott's results by assuming that anesthesia and 

 certain drugs which ordinarily deplete the adrenals of epineph- 

 rine act by preventing the formation of epinephrine and at 

 the same time do not interfere with its discharge. 



The blood pressure rise observed on stimulating the splanch- 

 nics is only partly due, however, to the liberation of epineph- 

 rine, for this pressure effect is in great part obtainable after 

 occlusion of the adrenal veins. The second peak of the blood 

 pressure curve obtained during splanchnic stimulation usually 

 disappears after exclusion of the adrenals from the circulation. 

 The occurrence of this peak has, therefore, been attributed to 

 the release of epinephrine into the general circulation under the 

 influence of the splanchnic stimulation. 270 • 639 



Continued stimulation of the splanchnics may cause the 

 discharge of large amounts of epinephrine from the adrenals. 

 Thus Stewart and Rogoff 625 found that 0.4 mgms. of epi- 

 nephrine was discharged from one adrenal of a cat during 4 

 hours of intermittent faradic stimulation of the splanchnic 

 nerve. This quantity represents about twice the normal 



