Effect of bucladesine sodium on the plasma concentrations and urinary excretion of purine bases and uridine

To examine whether bucladesine sodium affects the plasma concentrations of purine bases (hypoxanthine, xanthine, and uric acid) and uridine, 100 mL of physiological saline containing bucladesine sodium (6 mg/kg weight) was administered intravenously to eight healthy subjects for 1 hour after overnight fast except for water. Blood was drawn 30 minutes before, and 30 minutes and 1 hour after the beginning of the infusion, and 1-hour urine was collected before and after the beginning of the infusion. Two weeks later, 100 mL of only physiological saline was administered under the same protocol. Bucladesine sodium decreased the plasma concentrations of hypoxanthine by 36% and by 37%, and of xanthine by 16% and 33%, and of uridine by 17% and 30%, 30 minutes and 1 hour after the beginning of the infusion, respectively, and increased the urinary excretion of hypoxanthine and uric acid by 140% and 30%, respectively, after the beginning of the infusion. However, it did not affect the plasma concentration of uric acid or the urinary excretion of xanthine, and the urinary excretion of uridine was less than 0.2 micromol/h before or after bucladesine sodium infusion. On the other hand, physiological saline alone did not affect any of the values described. These results suggest that bucladesine sodium acts on the secretory process of the renal transport of hypoxanthine, resulting in the increased urinary excretion of hypoxanthine, and further suggest that bucladesine sodium enhances the uptake of uridine in plasma to liver cells.