Effects of exercise and grape juice ingestion in combination on plasma concentrations of purine bases and uridine

BackgroundSince grape juice contains considerable amounts of fructose, which may increase the plasma concentration of urate, the combination of exercise and grape juice may increase the plasma concentration of urate to a greater degree than grape juice or exercise alone.MethodsWe performed 3 experiments with 6 healthy male Japanese. The first was exercise alone (exercise alone experiment), the second was grape juice ingestion alone (grape juice alone experiment), and the third was a combination of exercise and grape juice ingestion (combination experiment).ResultsIn the exercise alone experiment, the concentrations of purine bases and uridine in plasma, and lactate in blood, as well as the urinary excretion of oxypurines were increased, whereas the urinary excretion of uric acid and fractional excretion of purine bases were decreased. In the grape juice alone experiment, the concentrations of purine bases and uridine, as well as lactate in blood were increased, whereas the fractional excretion of uric acid was decreased. In the combination experiment, the concentrations of purine bases and uridine in plasma, and lactate in blood, as well as the urinary excretion of oxypurines were increased, whereas the urinary excretion of uric acid and fractional excretion of hypoxanthine, xanthine, and uric acid were decreased. The increase in plasma concentration of urate by the combination of exercise and grape juice was greater than that by each alone, though it was not significantly different from the sum of increases in those 2 experiments.ConclusionIncreases in adenine nucleotide degradation and lactic acid production caused by both exercise and grape juice ingestion play an important role in the increase in plasma concentration of urate, while those in combination have an additive effect on that concentration.