The Thai Journal of Veterinary Medicine


Glutamine is known to modulate the uptake activity of nutrient transporters in mammalian cells. The aim of the study was to elucidate the influence of absence of extra- or intracellular glutamine on the uptake activity of the amino acid transport system A in placental BeWo cells. Extracellular glutamine was absent by culturing the cells in regular medium without glutamine. Intracellular glutamine was depleted by culturing the cells in regular medium without glutamine and by treating the cells for 16 hours with methionine sulfoximine (MSX), an inhibitor of glutamine synthetase. When BeWo cells were treated with glutamine-free culture medium for 1-30 hours, the uptakes of MeAIB and glutamine were higher than those with regular medium added glutamine. In addition, when these cells were treated with the absence of extracellular glutamine with or without 2 mM MSX, the uptake of not only methylaminoisobutyric acid (MeAIB) but also glutamine was measured in the presence of increasing concentrations (0-10 mM) of glutamine and of MeAIB, respectively. The data show that the uptake of MeAIB was inhibited by MSX treatment and the entry of MeAIB into the cells was effectively blocked by glutamine. In contrast, the uptake of glutamine was not affected by MSX treatment and that entry of glutamine into the cells was not affected by MeAIB. The reason why glutamine uptake in the placental cells was not affected by MSX treatment is there are some other amino acid transport systems for entry of glutamine instead of system A. The elucidated role of such regulation of glutamine should aid the rational utility of this amino acid in acting nutrient.

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