Metabolic effects of dietary purine in rats

The effect of different dietary purines on the metabolism of serum and urinary uric acid, allantoin, creatinine, urea nitrogen and urea was examined in the rat. Experimental diets were synthetic and they were given ad libitum during a 6-day experimental period. The results were compared with the renal morphological changes. The results obtained were as follows: Hypoxanthine, inosine, guanosine and guanine were readily converted to uric acid and allantoin, whereas adenine was metabolized quite differently from other purines. In particular, the intake of adenine exhibited a decrease of the uric acid excreted in the urine. Furthermore, an increase of creatinine, urea nitrogen and urea in the serum as well as a reduction in their urine excretion were observed in rats fed on the adenine diet. Adenine produced a nephrotoxic condition as reflected in the histological changes. From these observations, it is concluded that although the administered purines are closely related structurally, they are metabolized in so many different ways that some of the metabolites, particularly of adenine, may cause a potential nephrotoxicity.