BASES DERIVED FROM THE PROTEINS 229 



^-Hydroxyphenylethylamine (I.) is of interest chiefly because 

 of its relationship to adrenaline (II.) : 



I. II. 



Ho(~ ")CH 5 . CH 2 . NH 2 ™V" ^ScH(OH) . CH 2 . NH . CH 3 



There is a considerable quantitative difference between the 

 two bases with regard to the pressor action they exert when 

 injected intravenously, 1 milligram of the former base corre- 

 sponding roughly to 7 V milligram of the latter. The nature 

 of the action exercised by the two drugs is very similar, as 

 Dale and Dixon have shown (Journ. Physiol. 1909, 39, p. 25). 

 The effects produced by adrenaline (adrenine) simulate very 

 closely those produced on stimulating nerves of the true sym- 

 pathetic system, the activity being limited to muscle-fibres and 

 gland-cells innervated by this system. />-Hydroxyphenylethyl- 

 amine (and other monamines, including paraffinoid amines like 

 *s<9-amylamine) also simulate the effects of sympathetic nerves 

 and are therefore also sympathomimetic (Barger and Dale, 

 Journ. Physiol. 19 10, 41, 21). 



Of the amines derived from amino-acids by loss of carbon 

 dioxide, />-hydroxyphenylethylamine is chemically most nearly 

 related to adrenaline and, at the same time, it is most like this 

 base in its action. But many intermediate compounds of the 

 class are conceivable ; a large number of these have now been 

 synthesised and their physiological action has been ascertained. 

 The only other substance of this class occurring naturally is the 

 alkaloid hordenine or N-dimethyl-^-hydroxyphenylethylamine. 



Synthesis of Derivatives of Phenylethylamine. Relation- 

 ship of Chemical Constitution to Physiological Action 



Adrenaline. — This substance, one of the most potent drugs 

 used in therapeutics, occurs in the adrenal gland of mammals to 

 the extent of a few parts per thousand — in such minute amounts, 

 in fact, that the glands of 40,000 bullocks afford only one kilogram 

 of the substance. 1 As little as ^V of a milligram injected in- 

 travenously into a cat will produce a very great rise of blood 



1 Quite recently Abel and Ulacht (Journ. Amer. Med. Assoc. 191 1, 56, 153) 

 have met with adrenaline to the extent of about 5 per cent, in the secretion of the 

 so-called parolid gland in the skin of a Central American toad (Bu/o agua). 



