Uptake and supply of purine compounds by the liver.

We have analyzed for purine compounds entering and leaving the liver in lightly anesthetized rabbits and rats and for the export of utilizable purine from liver perfused with oxypurine. The in vivo results indicate that roughly 80% of hypoxanthine, xanthine, and urate is removed in a single passage of blood through liver. Conversely, the adenosine concentration of hepatic venous blood is increased 10-fold over portal or arterial levels. When the liver is isolated and perfused with hypoxanthine there is significant release of adenosine, whether measured quantitatively by microbiological assay or qualitatively by analysis of the radioactive purines released from liver that has been prelabeled with [14C]hypoxanthine. These results provide direct evidence for the clearance of hydroxylated purines and the release of utilizable adenine derivatives by liver.