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This Article Full Text Full Text (PDF) All Versions of this Article: 89/3/279    most recent expphysiol.2003.026666v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Antunes, V. R. Articles by Machado, B. H. Search for Related Content PubMed PubMed Citation Articles by Antunes, V. R. Articles by Machado, B. H. Related Collections Autonomic Neuroscience Cardiovascular control

Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, 14049-900, Ribeirão Preto, São Paulo, Brazil

The possible interaction of glutamatergic metabotropic agonists and N-methyl-D-aspartate (NMDA) receptors was investigated in the nucleus tractus solitarii (NTS) of awake rats. The cardiovascular responses to unilateral microinjection of trans-1-amino-1,3-cyclopentanediocarboxylic acid (trans-ACPD; 250 pmol/50 nL) into the NTS (n= 8) produced hypotension (–64 ± 4 mmHg) and bradycardic (–206 ± 11 bpm) responses, which were blocked by previous microinjection of 2-amino-5-phosphonovaleric acid (AP-5; 10 nmol/50 nL), a selective antagonist of NMDA ionotropic receptors, into the same site. Intravenous injection of methyl-atropine blocked both the bradycardic and hypotensive responses to microinjection of trans-ACPD into the NTS, indicating that the hypotension was secondary to the intense bradycardic response. The data also showed that the bradycardic and hypotensive responses to microinjection of an NMDA agonist (10 pmol/50 nL) into the NTS were not affected by previous microinjection of -methyl-4-carboxyphenylglycine (MCPG; 5 nmol/50 nL), a non-selective antagonist of metabotropic receptors. The results showing that the cardiovascular responses to microinjection of trans-ACPD into the NTS were blocked by AP-5 indicate that the responses to metabotropic agonists in the NTS involves NMDA receptors.

(Received 6 October 2003; accepted after revision 9 February 2004; first published online 17 February 2004)
Corresponding author B. H. Machado: Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, 14049-900, Ribeirão Preto, São Paulo, Brazil. Email: bhmachad{at}fmrp.usp.br