AMINES DERIVED FROM PROTEIN 



an intravenous injection of 0-065 grm. of the hydrochloride [Berthelot 

 and Bertrand, 1912, 3]. 



Lately the close similarity between the symptoms of poisoning by 

 /9-iminazolyl-ethylamine and those of anaphylactic shock have been 

 emphasised anew by Oehme [1913]. He and Loewit [1913 ; Ch. V, 

 methyl guanidine] both criticise the conclusion of Heyde [1912 ; Ch. 

 V, methylguanidine] that methylguanidine rather than iminazolyl- 

 ethylamine is of importance in this respect. 



The supposed connection between /8-iminazolyl-ethylamine and ana- 

 phylactic shock has even led to the statement (by Aronson [1912]) 

 that the amine is formed by incubating histidine with normal guinea-pigs' 

 serum, but this has been disproved by Friedberger and Moreschi 

 [1912] and Modrakowski [1912] denies that the amine is the cause of 

 anaphylactic shock since it does not render the blood incoagulable. 



In recording the fact, " as a point of interest and possible signifi- 

 cance," that the immediate symptoms with which an animal responds 

 to an injection of a normally inert protein, to which it has been 

 previously sensitised, are to a large extent those of poisoning by 

 ^-iminazolyl-ethylamine, Dale and Laidlaw consider that "the corre- 

 spondence cannot yet be regarded as sufficient basis for theoretical 

 speculation ". Pfeiffer thinks that y9-iminazolyl-ethylamine will cer- 

 tainly be of significance for the solution of the problem of anaphylaxis. 



The effect of iminazolyl-ethylamine on the vascular system is 

 complex and varies in different species, as well as in the same species 

 under different conditions. In rodents a rise of blood-pressure occurs, 

 owing to constriction of the arterioles, but may be masked by embar- 

 rassed respiration. It was the different behaviour of rabbits to the 

 base from histidine and that from ergot, which led Kutscher [1910, I] 

 to regard the two bases as different. Barger and Dale [1910, 3] have 

 however shown that both kinds of physiological effect are obtainable 

 with the base from either source, so that the identity cannot be doubted. 

 In carnivora, in the fowl, in the monkey (and probably therefore in 

 man) iminazolyl-ethylamine causes vasodilatation and a fall of systemic 

 blood pressure. The following table (Barbour [1913]) gives the effects 

 of the amine, compared with those of adrenaline and p-hydroxy-phenyl- 

 ethylamine : 



+ means rise of blood pressure or constriction, - the opposite ; the last-named amine 

 may have a pressor effect in some animals. 



