PART II. THE MEDULLA 



The medulla of the adrenal is characterized by the presence 

 within it, in rather high concentration, of epinephrine, a sub- 

 stance whose remarkable pharmacological actions has made it 

 the subject of intense study. The existence of this chemically 

 potent substance was first observed by Vulpian, 652 who, in 

 1856, noted the green coloration which occurred on moisten- 

 ing the medulla with a dilute solution of ferric chloride. 

 Henle 293 first observed the "bichromate" reaction in which the 

 medulla assumes a characteristic brownish discoloration when 

 treated with a solution of a salt of chromic acid. Because of 

 this reaction, which is shared by certain extra-medullary tis- 

 sues, the generic term "chromaphir' tissue is applied to these 

 structures. 



Oliver and Schafer 480 in 1894 and Szymonowicz, 616 inde- 

 pendently, first called attention to the remarkable blood pres- 

 sure rise which followed the injection of an extract of the 

 adrenal medulla. Lewandowsky, 391 in 1898, and Langley, 378 in 

 1901, called attention to the similarity in the pharmacody- 

 namic effects of epinephrine and the effects elicited by stimu- 

 lation of the sympathetic nerve fibers. With rare exceptions 

 this similarity in function has been confirmed, and epinephrine 

 is classed as a sympathomimetic substance because it mimics 

 in its effects the results of sympathetic nervous stimulation. 36 



The iron chloride reaction of the adrenal medulla (Vulpian's 

 reaction) and the relatively high concentration in which epi- 

 nephrine occurs in the adrenals rendered it relatively easy to 

 isolate and identify this substance. The discovery of epi- 

 nephrine, its isolation, and the demonstration of its powerful 

 pharmacodynamic action focused all attention on this sub- 

 stance as the important product of the adrenal gland. For 

 the following two decades much work was done on its pharma- 



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