Abstract
1760 Our previous research showed decreased lytic units per natural killer (NK) cell after one month of intensive training. Although the proportion of NK cells with a low cytotoxicity was increased, this change did not entirely explain the observed changes. PURPOSE: We thus investigated plasma levels of glutamine (the essential energy source of lymphcytes) to test the hypothesis that intensive training decreased plasma glutamine and thus NK cell cytotoxicity. METHODS: Eight college-level female volleyball players undertook one-month of heavy pre-season training 5h/day, 6 days per week. After an overnight fast, four morning resting blood samples were collected: pre-training, on the 10th day of training, one day before the end of training and one week after training, respectively. Plasma glutamine, glutamic acid and total amino acid concentrations were determined by HPLC. RESULTS: Plasma glutamine, glutamic acid and total aminoacid levels remained unchanged throughout the experiment. However, all glutamine concentrations (46.2–171.1 mmol/l) were substantially below the normal range (420–500 mmol/l). In contrast, glutamic acid levels were higher than normal, and total amino acid concentrations remained within the normal range. DISCUSSION: Our results do not explain training-induced changes in NK cell cytotoxicity, although low initial plasma glutamine levels may already have depressed NK cell cytotoxicity. CONCLUSIONS: One-month of heavy training did not change plasma glutamine levels of female volleyball players. These results do not support a link between plasma glutamine concentrations and decreased NK cell cytotoxicity during training. Supported by the Grant-in-Aid for Scientific Research C-2, 11680058, Japan Society for the Promotion of Science.
Published Version
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