576 GASTROINTESTINAL "AUTOINTOXICATION" 



Cresol (chiefly paracresol), para-oxyphenyl acetic acid, and para- 

 oxyphenyl propionic acid appear under similar conditions, except 

 that the two oxy-acids are possibly also formed within the body 

 through cellular metabolism, as they have been found present in the 

 urine independent of intestinal putrefaction. Paracresol is quanti- 

 tatively the most important of the urinary phenols, and long continued 

 feeding produces no noticeable effects in rabbits."^'*'' Probably part of 

 the benzoic acid that appears in the urine combined with glycocoll, as 

 hippuric acid, is derived from intestinal putrefaction.^'' 



THE PRESSOR BASES 40 



Among the products of protein putrefaction are several amines that 

 have marked power to stimulate the sympathetic nervous system and 

 thus to raise the blood pressure, hence resembling epinephrine physio- 

 logically as well as chemicall.y. Since increase in blood pressure is so 

 important a condition in clinical medicine these substances are of 

 much significance. The most important of the pressure-raising bases 

 are, in the order of their pressor effect : — 



Phenyl-ethylamine C„H,.CH,.CH,.XH„ 



derived from phenylalanine C,H,.CH,.CHNH,.COOH. 



Para-hj'droxy-phenjd-ethylamine ( t^ramine ) Oil . C Jl^ . CIL . CHj . XH, 



derived from tyrosine OH.CeH,.CH,.CHXH,.COOH. 



Its relation to epinephrine is seen on comparing with the structural 

 formula of the latter ( OH ) ,CeH3 . CHOH . CH.NH . CH3 



.XH — CH 

 Beta-iminazolyl-ethyl'amine (histamine) CH^ 



^X — C — CH„:CH,.XH, 



/XH — CH 

 derived from histidine CH^ || 



\\X — C — CH, . CHXH„ . COOH 



It will be observed that these are all amines derived from the cyclic 

 amino-aeids of proteins by the process of decarboxylization (loss of 

 COo), a process which occurs only under anaerobic conditions. The 

 straight chain amines are much less active ])hysiologically. These sub- 

 stances have all been found in puti'id protein materials, produced by 

 the action of anaerobic bacteria, and possibly they are formed in the 

 intestines. Para-hydroxy-phenyl-ethylamine is also one of the active 

 constituents of ergot, and has been found in the salivary gland of 

 cephalopods, where it functions as a venom in parcilyzing the prey. 

 Beta-iniiiiazolyl-ethylamine is also })resent in ergot. 



These substances are all detoxicated by the liver, and hence have lit- 



3«b Denny and Frothingliam, Jour. Med. Res., 1914 (31), 277. 



30 See Prager, Med. Xews, 1005 (SG), 1025; Magnus-Levy, Miincli. med. Woch., 

 1905 (52), 2168. 



40 Full bihliography given l)y Hargor, "The Simph'r Xatural Bases," Mono- 

 graphs on Biochemistry, London, 1914. 



