Received October 6, 2003
Revised November 28, 2003
Accepted after revision February 9, 2004
NMDA receptor antagonism blocks the cardiovascular
responses to microinjection of trans-ACPD into the NTS
of awake rats
Vagner R. Antunes 1,
Leni G.H. Bonagamba 1,
Benedito H. Machado 1*
1 University of Sao Paulo
* To whom correspondence should be addressed. E-mail: bhmachad{at}fmrp.usp.br.
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Abstract |
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The possible interaction of glutamatergic metabotropic
agonists and NMDA receptors was investigated in the NTS
of awake rats. The cardiovascular responses to
unilateral microinjection of 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 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 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.
Key Words:
Blood pressure, Cardiovascular, NMDA (N-methyl-D-aspartate)
