J. Arly Nelson

Transport and metabolism of purines by isolated choroid plexus, liver and brain in the spiny dogfish, Squalus acanthias☆

Abstract 1. 1. The transport and metabolism of [2-14C]-xanthine and of [8-14C]-hypoxanthine were studied in isolated choroid plexus of the spiny dogfish, Squalus acanthias. 2. 2. Both purines are accumulated in choroid plexus by a specific, carrier-mediated transport mechanism. Xanthine transport is inhibited by structural analogs containing an enolizable hydroxyl group at carbon atom No. 6 of the purine ring. 3. 3. Neither xanthine nor hypoxanthine was metabolized extensively by choroid plexus. 4. 4. The concentration of hypoxanthine in plasma, CSF and extradural fluid was measured by high pressure liquid chromatography. 5. 5. The activities of several purine metabolizing enzymes were determined for brain, liver and choroid plexus.