title: Guanosine enhances glutamate transport capacity in brain cortical slices.
abstract: 1. The effect of guanosine on L-[3H] glutamate uptake was investigated in brain cortical slices within physio-pathological range of glutamate(1-1000 microM). In these conditions, glutamate uptake was significantly enhanced in slices treated with 100 microM guanosine only at 100 and 300 microM glutamate (44 and 52%, respectively). 2. Evaluation of kinetic parameters showed that guanosine affected significantly only uptake Vmax (23%). 3. The guanosine withdrawal did not abolish its significant effect on glutamate uptake when 100 or 300 microM glutamate were used (an increase of 66 and 35%, respectively). 4. These results support the hypothesis of a protective role for guanosine during excitotoxic conditions when glutamate levels are enhanced (e.g. brain ischemia and seizures), possibly by activating glutamate uptake. Moreover, our results may contribute to understand the antiexcitotoxic mechanism of guanosine on glutamate transport, giving new information concerning its mechanism of action.
authors.affiliation: Departamento de Bioquímica ICBS, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600 (Anexo), Porto Alegre, RS, 90035-003, Brazil. frizzo@ufrgs.br
authors.forename: Marcos Emílio
authors.initials: ME
authors.lastname: Frizzo
authors.forename: Fábio Duarte
authors.initials: FD
authors.lastname: Schwalm
authors.forename: Juliana Karl
authors.initials: JK
authors.lastname: Frizzo
authors.forename: Félix Antunes
authors.initials: FA
authors.lastname: Soares
authors.forename: Diogo Onofre
authors.initials: DO
authors.lastname: Souza
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002540:Cerebral Cortex / Q000378:metabolism*; D005260:Female; D018698:Glutamic Acid / Q000493:pharmacokinetics*; D006151:Guanosine / Q000494:pharmacology*; D008297:Male; D009924:Organ Culture Techniques; D051381:Rats; D017208:Rats, Wistar; D014316:Tritium
chemical_list: D014316:Tritium; D006151:Guanosine; D018698:Glutamic Acid