NUCLEIN OR PURINE METABOLISM 



881 



low and a high protein diet respectively. Although in each case 

 care was taken to exclude purine-containing bodies from the food, 

 the output of uric acid on the high nitrogenous diet was double as 

 much as on the low diet. All we can say is that uric acid is constantly 

 being derived from the tissue disintegration, but that it varies under 

 different conditions of nutrition as well as under different conditions of 

 activity of the body. 



There are two main conditions which give rise to a marked increase 

 in the output of endogenous uric acid. These are (1) severe muscular 

 activity, (2) febrile states accompanied by increased nitrogenous meta- 

 bolism. Since both these conditions are associated with an increased 

 breakdown of muscle substance we may regard the uric acid as 



11 12 



10 



11 U 



FIG. 353. Curves showing the hourly excretion of uric acid and urea after a single 

 meal. (HOPKINS.) The continuous line =,uric acid output ; the dotted 

 line = urea output. 



derived especially from the hypoxanthine or its precursors, such as 

 inosinic acid, contained in the muscle. 



The foods which are especially effective in causing increase in the 

 exogenous uric acid are those rich in nuclein, such as sweetbreads 

 or liver, and those rich in hypoxanthine or its precursors, such as meat 

 or meat extract. When these foods are taken, or when nucleic acid 

 itself is administered, a condition of leucocytosis is generally produced, 

 the number of leucocytes in the blood being increased as much as 

 three times. It has been suggested that the uric acid is actually 

 formed by a disintegration of the newly formed leucocytes and not by 

 a direct conversion of the purines of the food. It is quite possible, as 

 suggested by Schittenhelm, that the leucocytes play a part in the 

 transference of the nucleins from the intestine to the circulation. But 

 the absence of any absolute proportionality between the degree of 

 leucocytosis and the amount of uric acid excreted points to the 



56 



