We studied the incorporation of C-14-formate into uric acid and allant
oin in different organs (liver, lung, kidney, spleen), isolated hepato
cytes, perfused liver and urine of the rat. Allantoin had a higher spe
cific radioactivity than uric acid after C-14-formate load in the live
r in vivo. This was found to be a strictly hepatic phenomenon and not
due to the influence of other tissues