Renal urate transport during variations in urate synthesis in the rat

Summary In order to determine the effect of intrarenal synthesis of urate upon the urinary urate excretion in the rat, we effected large changes in urate synthesis by increasing it with hypoxanthine and decreasing it with allopurinol. Hypoxanthine infusion increased plasma urate rapidly and also increased the urinary urate excretion and its renal clearance. However, when the plasma urate was maintained constant, hypoxanthine had no effect upon renal urate transport. Conversely, allopurinol infusion rapidly diminished the plasma urate, urinary urate excretion and its renal clearance. Again, the maintenance of a constant plasma urate concentration prevented any change in urate transport during allopurinol. The urinary degradative purine metabolite pattern was altered pre-dictably by hypoxanthine and allopurinol. Assuming that any putative intrarenal component of urate synthesis would be affected predictably and consistently by hypoxanthine and allopurinol, these results suggest that changes in intrarenal urate synthesis are not an important determinant of urate excretion in the rat.Reported in abstract form in Clinical Research23, 508 A (1975)