58 The Endocrine Organs 



The Nature of the Autacoid furnished by the Medulla 



All the physiological effects which are about to be described as yielded 

 by suprarenal extracts are obtainable from extract of medulla alone : 

 intravenous injection of extract of cortex gives no appreciable result. In 

 Teleostei, where the cortex is represented by the corpuscles of Stannius, 

 and in the Elasmobranchs, in which the cortex is represented by the inter- 

 renal body and the medulla by the entirely separate " paired bodies " of 

 Balfour, it has been shown by Vincent that the latter yield an active 

 extract, whilst extracts of the interrenal body are inactive. It was proved 

 by Moore that the action of the extract of medulla is due to the material 

 within the cells which becomes stained with chromic salts, and which, as 

 Vulpian showed, is readily oxidised by various reagents, giving character- 

 istic colour reactions with ferric chloride, chlorine water, and caustic 

 alkalies. A similar reaction was obtained by Vulpian with a material 

 contained in the blood of the suprarenal vein. With phospho-tungstic 

 acid a blue colour is yielded even in extreme dilution. 



This chromaphil substance of the suprarenal medulla, after being partly 

 isolated by Fraenkel, was prepared in a condition approaching purity by 

 v. Flirth, and by Abel, and eventually in a crystalline form by Takamine 

 and by Aldrich. It has received various names, such as suprarenin 

 (v. Fiirth), epinephrin (Abel), adrenalin (Takamine), the last being that 

 by which it is most widely known. 1 It has been estimated by Batelli that 

 the suprarenal capsules contain about 1 part of adrenalin per 1000 of the 

 whole gland, but as it only occurs in the medulla, which forms less than a 

 fourth of the gland, the proportion in this would be considerably greater. 



Adrenalin can be prepared synthetically, methyl-acetyl-pyrocatechin 

 being first obtained. This when reduced gives a racemic salt which can 

 be split into cZ-adrenalin and ^-adrenalin. The latter appears to be in all 

 respects identical with the natural product, while the racemic salt and 

 c?-adrenalin are much less active physiologically. 



Chemically adrenalin is ortho-dioxyphenyl-ethanol-methylamine : 

 CH 8 . NH . CH 2 . CH . OH 



OH 

 OH 



and is related to tyrosine (oxyphenyl-amino-propionic acid). 



Effects of Intravenous Injection of Suprarenal Extracts 

 If an extract or decoction of the medulla — made with water or Ringer's 

 solution — is injected into a vein, an immediate and marked rise of blood- 

 pressure is produced. This is caused by contraction of the peripheral 



1 This name has been adopted in the British Pharmacopoeia and will therefore be 

 employed in this work. 



