Metabolism of exogenous adenine in a pyruvate kinase-deficient patient

Abstract

The metabolism of adenine, administered intravenously and orally, was studied in a patient with red cell pyruvate kinase (PK)-deficiency. Intravenous infusion of 58.5 μmol of adenine per kg containing 6475 Bq of 8-¹⁴C adenine caused an initial decrease in red cell ATP level and the gradual return to the pre-infusion level coincided with an increase in radiolabeled ATP. Of the infused adenine, 1.3% had entered the red cell pool after 2 h. The route of administration affected the urinary excretion of adenine and its oxymetabolites; after 6 h, 10.7% of the infused adenine had been excreted, compared with 7.4% after ingestion of a similar dose. In 10 control subjects given 45.1–55.5 μmol/kg, excretion of adenine plus oxymetabolites accounted for 13.5 ± 2.9% of the ingested dose. Differences were also observed in the urinary purine excretion patterns for the two routes of administration. This study has shown that adenine can be incorporated into ATP in the red cells of a PK-deficient patient.

Key Words:

• erythrocyte nucleotides
• urinary purines