NMDA receptors in NTS are involved in the bradycardic but not in the pressor response of chemoreflex.
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Date
1995
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Abstract
Activation of carotid chemoreceptors with intravenous potassium
cyanide (KCN) produces increases in arterial pressure,
bradycardia, and tachypnea. In the present study, we activated
carotid chemoreceptors with KCN and the neurotransmission
of the chemoreceptor reflex into the commissural nucleus
tractus solitarii (NTS) was blocked with phosphonovaleric acid
@P-5), an N-methyl-D-aspartate (NMDA)-selective antagonist.
The aim of this study was to evaluate the involvement of
NMDA receptors in the cardiovascular and respiratory responses
produced by chemoreceptor activation in unanesthetized
rats. The pressor response to KCN was not changed after
microinjection of three different doses of AP-5 into the NTS,
whereas the bradycardic response was reduced in a dosedependent
manner. The increase in respiratory frequency in
response to carotid chemoreceptor activation was also not
affected by AP-5 microinjected into the NTS. The data indicate
that the activation of the cardiovagal component of the
chemoreflex in the commissural NTS is mediated by NMDA
receptors, whereas pressor and ventilatory responses are not.
Description
Keywords
Excitatory amino acid, phosphonovaleric acid, Cardiovascular regulation, Heart rate control
Citation
HAIBARA, A. S. et al. NMDA receptors in NTS are involved in the bradycardic but not in the pressor response of chemoreflex. American Journal of Physiology. Heart and Circulatory Physiology , v. 38, n.269, p. H1421-H1427, 1995. Disponível em: <http://ajpheart.physiology.org/content/269/4/H1421.long>. Acesso em: 19 fev. 2017.