AJP - Renal Physiology, Vol 238, Issue 6 481-F487, Copyright © 1980 by American Physiological Society
Quantification of renal uric acid synthesis in the rat
T. Y. Chin, W. Cacini, M. J. Zmuda and A. J. Quebbemann
The excretion of nephrogenic uric acid in the urine of Sprague-Dawley rats
was estimated by use of the isotope-dilution technique. In nonfasted rats
the urine-to-plasma specific activity ratio (SAR) of [14C]uric acid was
0.93, suggesting that a minimum of 7% of the uric acid excreted in the
urine is synthesized in the kidney. During hypoxanthine infusion the SAR
decreased in a dose-related fashion, indicating that the rat kidney is
capable of synthesizing relatively large amounts of uric acid and that
circulating precursor levels may in part regulate the renal synthesis of
uric acid. During allopurinol infusion the SAR increased to 1.0,
demonstrating that the SAR is a valid indicator of the contribution of
nephrogenic uric acid excreted into the urine. Results of perfusion studies
in isolated rat kidneys suggest that uric acid is the major end product of
purine catabolism in the rat kidney and that some uric acid formed in the
kidney may be absorbed directly into the circulation.
