Contribution of excitatory amino acid receptors of the retrotrapezoid nucleus to the sympathetic chemoreflex in rats

Autor(es)

Takakura, Ana C. ^[1] ; Moreira, Thiago S. ^[2]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Biomed Sci, Dept Pharmacol, BR-05508900 Sao Paulo - Brazil

^[2] Univ Sao Paulo, Inst Biomed Sci, Dept Physiol & Biophys, BR-05508900 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Experimental Physiology; v. 96, n. 10, p. 989-999, OCT 2011.
• Citações Web of Science: 23

Resumo

In the present study, we evaluated the role of glutamatergic mechanisms in the retrotrapezoid nucleus (RTN) in changes of splanchnic sympathetic nerve discharge (sSND) and phrenic nerve discharge (PND) elicited by central and peripheral chemoreceptor activation. Mean arterial pressure (MAP), sSND and PND were recorded in urethane-anaesthetized, vagotomized, sino-aortic denervated and artificially ventilated male Wistar rats. Hypercapnia (10% CO(2)) increased MAP by 32 +/- 4 mmHg, sSND by 104 +/- 4% and PND amplitude by 101 +/- 5%. Responses to hypercapnia were reduced after bilateral injection of the NMDA receptor antagonist D,L-2-amino-5-phosphonovalerate (AP-5; 100mm in 50 nl) in the RTN (MAP increased by 16 +/- 3 mmHg, sSNDby 82 +/- 3% and PND amplitudeby 63 +/- 7%). Bilateral injection of the non-NMDA receptor antagonist 6,7-dinitro-quinoxaline-2,3-dione(DNQX; 100 mm in 50 nl) and the metabotropic receptor antagonist (+/-)-alpha-methyl-4-carboxyphenylglycine (MCPG; 100mm in 50 nl) in the RTN did not affect sympathoexcitatory responses induced by hypercapnia. Injection of DNQX reduced hypercapnia-induced phrenic activation, whereas MCPG did not. In animals with intact carotid chemoreceptors, bilateral injections of AP-5 and DNQX in the RTN reduced increases in MAP, sSND and PND amplitude produced by intravenous injection of NaCN (50 mu g kg(-1)). Injection of MCPG in the RTN did not change responses produced by NaCN. These data indicate that RTN ionotropic glutamatergic receptors are involved in the sympathetic and respiratory responses produced by central and peripheral chemoreceptor activation. (AU)

• Processo FAPESP: 10/09776-3 - Mecanismos neurais envolvidos na geração do ritmo expiratório: possível envolvimento do núcleo retrotrapezoide e da região parafacial
• Beneficiário: Ana Carolina Takakura Moreira
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 06/60174-9 - Mecanismos neurais envolvidos na integração do quimioreflexo central e periférico
• Beneficiário: Thiago dos Santos Moreira
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores