During prolonged maximal exercise,
oxygen deficits occur in working muscles. Progressive
hypoxia results in the impairment of the oxidative resynthesis of
ATP and increased degradation of
purine nucleotides. Moreover,
ATP consumption decreases the conversion of
UDP to
UTP, to use
ATP as a
phosphate donor, resulting in an increased concentration of
UDP, which enhances
pyrimidine degradation. Because the metabolism of
pyrimidine nucleotides is related to the metabolism of
purines, in particular with the cellular concentration of
ATP, we decided to investigate the impact of a standardized exercise with increasing intensity on the concentration of
uridine,
inosine,
hypoxanthine, and
uric acid. Twenty-two healthy male subjects volunteered to participate in this study. Blood concentrations of metabolites were determined at rest, immediately after exercise, and after 30 min of recovery using high-performance liquid chromatography. We also studied the relationship between the levels of
uridine and indicators of myogenic
purine degradation. The results showed that exercise with increasing intensity leads to increased concentrations of
inosine,
hypoxanthine,
uric acid, and
uridine. We found positive correlations between blood
uridine levels and indicators of myogenic
purine degradation (
hypoxanthine), suggesting that the blood
uridine level is related to
purine metabolism in skeletal muscles.