Portal de Periódicos da CAPES

Uptake of L-glutamine into synaptosomes. Is the γ-glutamyl cycle involved?

1983; Elsevier BV; Volume: 33; Issue: 3 Linguagem: Inglês

10.1016/0024-3205(83)90380-6

1879-0631

Alain Minn, Dominique Besagni,

Lipid Membrane Structure and Behavior

Transport of L-glutamine into rat cortical synaptosomes has been investigated by (14C)L-glutamine uptake experiments. This amino acid enters synaptosomes both by an active carrier mediated system, which may be the result of gamma-glutamyl cycle activity and by a Na+-dependent transport system. This view is supported by the following observations: a) as demonstrated previously (10), glutamine inside synaptosomes reaches concentrations higher than those of the incubation medium, and initial rates of uptake approach saturation kinetics; b) the uptake of glutamine is inhibited by uncouplers; c) the uptake is inhibited by methionine sulfoximine, a suicide-inhibitor of an enzyme of the gamma-glutamyl cycle; d) the initial rate of uptake is lowered by decreasing the Na+-level of the incubation medium or by adding ouabain. The validity of this hypothesis is discussed.