ABSTRACT
OBJECTIVE: To investigate the effects of exercise and beer ingestion separately and combined on the plasma concentration of purine bases. METHODS: Six healthy men aged 30-39 years participated in 3 different experiments, in which they exercised for 30 min (at 70% of maximum oxygen uptake) and ingested beer (10 ml/kg body weight), or did each activity separately, with each experiment performed at 2 week intervals. RESULTS: The plasma concentration of uric acid was increased by 12% (p < 0.05), 8% (p < 0.01), and 29% (p < 0.01) with exercise, beer ingestion, and a combination of exercise and beer ingestion, respectively, which showed that it increased synergistically in the combination experiment. The fractional excretion of uric acid was decreased by 44% (p < 0.01) and 52% (p < 0.01) with exercise alone and a combination of exercise and beer ingestion, respectively, while it was increased by 15% (p < 0.05) with beer ingestion alone. Creatinine clearance was decreased by 16% (p < 0.01) with both exercise alone and a combination of exercise and beer ingestion, while it was not changed with beer ingestion alone. The increase in the plasma concentration of xanthine during the beer ingestion experiment was 2.1-fold greater than that during the combination (p < 0.05), while the increase in urinary excretion of xanthine caused by beer ingestion was 2.5-fold greater than that caused by a combination of beer and exercise (p < 0.05). Finally, exercise alone as well as a combination of beer and exercise increased the blood concentrations of lactic acid and NH3, whereas beer alone decreased concentration of pyruvic acid. CONCLUSION: These results suggest that the production of uric acid caused by both exercise and beer ingestion, as well as the inhibition of urinary uric acid excretion from a high blood lactic acid concentration, were the main contributors to the synergistic effect on the increase in plasma uric acid concentration. A decrease in creatinine clearance also contributed to the effect. We considered that pyruvic acid and NH3, produced in the muscles following exercise, relieved the beer induced increase of the plasma concentration and urinary excretion of xanthine, which may have played a minor role in the increase in plasma uric acid concentration.
