Artificially imposed electrical potentials drive L-glutamate uptake into synaptic vesicles of bovine cerebral cortex.
Biochem J
; 267(1): 63-8, 1990 Apr 01.
Article
em En
| MEDLINE
| ID: mdl-1970243
ABSTRACT
L-Glutamate is a major excitatory neurotransmitter in the central nervous system. MgATP-dependent glutamate uptake and H(+)-pumping ATPase activity were reported in highly purified synaptic vesicles [Naito & Ueda (1983) J. Biol. Chem. 258, 696-699; Shioi, Naito & Ueda (1989) Biochem. J. 258, 499-504], and it is hypothesized that an electrochemical H+ gradient across the vesicle membrane, the so-called protonmotive force, elicits the neurotransmitter uptake. An inside-positive diffusion potential across the vesicle membrane was established with valinomycin plus Rb+. This artificial electrical potential promoted the uptake of glutamate, but not aspartate, in the synaptic vesicles prepared from bovine cerebral cortex. The uptake was inhibited by the protonmotive-force dissipators carbonyl cyanide p-trifluoro-methoxyphenylhydrazone or nigericin, and was enhanced by concomitant imposition of a pH jump (alkalinization) in the external medium. Subcellular and subvesicular distributions showed the uptake system to be predominantly associated with small synaptic vesicles. The results support the hypothesis that glutamate uptake into synaptic vesicles is coupled with a H+ efflux down the electrochemical potential gradient, which is generated by H(+)-pumping ATPase.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Prótons
/
Vesículas Sinápticas
/
Córtex Cerebral
/
Glutamatos
Limite:
Animals
Idioma:
En
Revista:
Biochem J
Ano de publicação:
1990
Tipo de documento:
Article