Pharmacological characterization of glutamate Na+-independent transport in retinal cell cultures: implications in the glutathione metabolism.
L-glutamate is the primary excitatory neurotransmitter in the mammalian central nervous system (CNS). Mechanisms for the removal of glutamate are vital for maintaining normal function of retina. In the present study, using retinal cell cultures obtained from chick embryos, we characterize, pharmacologically, the presence of two glutamate transporter mechanisms, Na(+)-dependent and Na(+)-independent uptake systems. Na(+)-independent uptake system seems to present characteristics related to system x(CG)(-) (cystine-glutamate exchanger) that in the current work demonstrated highlighted contribution to the glutamate transport in retina, which is not observed in other tissues. Our results showed that glutamate shares x(CG)(-) system with another amino acid, L-cysteine, suggesting the possible involvement of this component in processes related to the release of the glutathione antioxidant molecule. Furthermore, cysteine uptake by Na(+)-independent transport appears to be more evident in glial cell cultures than in neuronal cell cultures. So, Na(+)-independent transport system seems to have other functions besides amino acid transport, demonstrating a physiological role in modulating cell redox status.
Oliveira
Karen Renata Matos
KR
Laboratório de Neuroquímica Molecular e Celular, Universidade Federal do Pará, Belém, PA, Brazil.
Herculano
Anderson Manoel
AM
Crespo-López
Maria Elena
ME
do Nascimento
José Luiz Martins
JL
D027182:Amino Acid Transport System y+ / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D003545:Cysteine / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D012160:Retina / Q000187:drug effects / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*
D027182:Amino Acid Transport System y+; C492255:Slc7a11 protein, mouse; D018698:Glutamic Acid; D012964:Sodium; D005978:Glutathione; D003545:Cysteine