Metabolism by Man of Intravenously Administered Adenine

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Abstract
A study was made of the metabolism by a human subject of adenine administered intravenously at a dose of 10 mg/kg with 200 .mu.Ci of 8-14C-adenine to compare this data with data from the rabbit. A rapid initial disappearance of radioactivity from the blood was followed by a slower loss with a half-life of about an hour. The 1st was probably due to diffusion into the extravascular fluid and the 2nd to metabolism in the tissues. Fifteen percent of the radioactivity infused was excreted in the urine during the 1st 3 h as unchanged adenine and another 8% was excreted during the 1st 6 h as a mixture, in almost equal parts, of 8-oxyadenine and 2,8-dioxyadenine. Radioactivity in the urine after the 2nd day, starting at 1.5% of the dose per day and declining steadily to 0.5% at 3 mo, was predominantly in uric acid, reflecting turnover of the adenine which had entered body pools of purine nucleotide. Approximately 2% of the injected radioactivity was incorporated into red blood cell AMP, ADP and ATP which by the 2nd day, had the same specific radioactivity, which then decayed at a rate of 1.3% per day. The results were remarkably similar to those obtained in a previous study on the rabbit. A variety of clinical observations and tests on blood and urine showed no abnormalities attributable to the infusion with adenine.