DEAMINIZATION 51 



The Presence of Ammonia in the Portal Blood. 



The first real experimental advance made as regards the rapid 

 deaminization which takes place during or soon after the process of 

 absorption was the work of Nencki (298) and his pupils. These 

 workers, when experimenting with dogs on which the Eck fistula opera- 

 tion had been carried out, found that the portal blood contained three 

 to four times more ammonia than the systemic blood. Further that 

 the ammonia content of the systemic blood approximated to that of 

 the portal after an Eck's fistula was made, i.e. the liver, cut out of the 

 circulation, no longer acted as a check to the entry of ammonia into 

 the systemic blood. They also noted that the gastric and intestinal 

 mucous membrane contained more ammonia at the height of digestion 

 than when at rest. Horodynski, Salaskin and Zaleski (203) confirmed 

 this work, and found that, although there was a definite increase of 

 ammonia in the portal blood compared with the systemic blood dur- 

 ing digestion, even during starvation the portal blood contained more 

 ammonia than the systemic. They also noted that the ammonia 

 content of the tissues and organs (the intestinal mucous membrane, 

 liver, etc.) intimately connected with the absorption and utilization 

 of food was diminished during starvation. Biedl and Winterberg (64) 

 denied that the portal blood contained, as a rule, more ammonia than 

 the systemic, although they admitted that the portal blood contained 

 at times more than the average amount of ammonia. They maintained 

 that the previous results of Nencki were largely due to faulty technique. 

 As their work was carried gut in 1902, and a reliable method is still 

 lacking for the quantitative estimation of ammonia in protein tissues 

 and fluids, their objection cannot be too seriously considered. The 

 comparatively recent work of Cohnheim with living tissue (97) gave 

 almost direct evidence of deaminization taking place during absorption. 

 He found that if isolated fish intestine, into which he had placed pro- 

 teose solution, were floated in Ringer's solution, partial deaminization 

 took place, as shown by the fact that ammonia and an unknown base 

 appeared in the Ringer solution. In conjunction with Makita (98) he 

 repeated this experiment introducing into the intestine glycine and 

 tyrosine as test substances. Glycine yielded ammonia, or perhaps more 

 correctly a volatile base, and from tyrosine ammonia was obtained. 

 Similar experiments were tried with the intestines of dogs and cats, 

 but without much success. 



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