Effects of fructose and xylitol on the urinary excretion of adenosine, uridine, and purine bases

To examine whether fructose and xylitol increase the plasma concentration a nd urinary excretion of adenosine, as well as uridine and purine bases (hyp oxanthine, xanthine, and uric acid), we intravenously administered xylitol and, 2 weeks rater, fructose, to five healthy subjects. Analyses of brood a nd urine samples obtained during these infusion studies demonstrated that f ructose increased the urinary excretion of adenosine and uridine 11.9- and 105.5-fold, respectively, and caused only a smalt increase in the plasma co ncentrations of uridine and purine bases, It was further demonstrated that xylitol increased the urinary excretion of uridine 58.4-fold, with a marked increase in the plasma concentrations of purine bases and uridine but with out an increase in the urinary excretion of adenosine. However, neither inf usion increased the plasma concentration of adenosine. These results sugges t that in addition to many organs, including the liver, fructose is signifi cantly metabolized by an abrupt adenosine triphosphate (ATP) consumption in the kidney, leading to an increase in the urinary excretion of adenosine a nd uridine. They also suggest that xylitol is not significantly metabolized in the kidney. Copyright (C) 1999 by W.B. Saunders Company.