422 THE METABOLISM OF THE PURIN BODIES 



dissolved in from 25-50 c.c. isotonic Nad were injected intra- 

 venously into dogs l the purin excretion, total N, and, in some 

 cases, the P 2 5 and NH 3 excretions, being determined every 

 one or two hours. In all cases a marked rise in purin-N was 

 observed during the hour or two following the injection of the 

 diuretic. This increase might, of course, have another cause than 

 that described above, viz. the injected substance might induce 

 an increased decomposition of tissue nucleins and a consequent 

 rise in endogenous production. That such was not the case was 

 proved in the dextrose experiments by the fact that the hourly 

 NH 3 excretion was also raised ; and, in the urea experiments, by 

 the fact that the P 2 5 excretions remained constant though the 

 purin-N rose. In the former case, the rise of NH 3 was probably 

 due to the same cause as the rise of purin-N, viz. that a larger 

 fraction of blood than normal had been carried directly to the 

 kidneys before it had traversed the liver, and that as a conse- 

 quence the precursors of urea which it contained (viz. NH 3 salts), 

 and which are converted into urea by the hepatic cells, were ex- 

 creted in large amount. The fact that the P 2 5 excretion 

 remained constant when urea was injected shows that no in- 

 creased nuclein disintegration could have occurred. 



The same type of experiment was attempted on man, diuretics 

 being given in the diet. No distinct increase could, however, 

 be observed in the hourly excretions of purins. The integral 

 factor in man is only 2, so that it would take an enormous 

 hyperaemia of the kidneys (to divert sufficient uric acid to 

 them) before any difference could be observed in the urinary 

 purins. 



Wiener ( 19 ) has suggested that the rise following the injection 

 of these substances indicates a synthesis of uric acid, and is not 

 due to the cause ascribed above. This possibility we will discuss 

 later. Siven ( 25 ) and Pfeil ( 26 ) have both noticed that on a 

 purin-free diet the purin excretion is greater in the forenoon and 

 least during night. It is greatest, therefore, just after the erect 

 posture is assumed, and when there is, conceivably, more active 

 circulation through the kidneys. 



1 These animals are very suitable for this experiment, as their integral 

 factor is high (i.e. their uric acid destructive power is great), and consequently 

 a marked difference would be expected to follow the diverting of uric acid 

 from the destructive organ. 



