Study of the Utilization and Excretion of Dietary Purines

In a previous study of this xanthinuric subject's purine metabolism, we observed that a tracer dose of adenine-8-14C given intravenously was excreted predominately as hypoxanthine and a tracer dose of guanine-8-14C predominately as xanthine. In addition, only 1 % of the adenine-8-'4C label was excreted on the first day after administration, as compared to 63 % of the guanine-8-14C label (1). This study was designed to determine whether similar differences in the incorporation and excre-tion of these purines could be observed if they were taken orally. The form and amounts of purine given were selected to approximate physiologic conditions and yet allow accurate quantitation. Ribonucleic acid and ribonucleotides were selected, since dietary purines would ordinarily appear in these forms in the gastrointestinal tract rather than as free bases. The quantity given was se-lected to be large enough to show significant dif-ferences in purine excretion without exceeding the subject's daily purine requirements. Methods The methods used in this study were reported in de-tail in prior publications (1, 2). These include methods of urine collection and storage; enzymatic and spectro-photometric analysis of uric acid, xanthine, and hypo-xanthine in urine and plasma; chemical analysis of cre-atinine by the alkaline picrate method; column chro-matographic and gradient elution methods for the sepa-ration and quantitation of the urinary purines; spectro-photometric methods for the identification and quantitation of individual purines; and methods for counting `C ac-* Submitted for publication June 20, 1966; accepte