Cardiovascular responses to microinjections of GABA or anesthetics into the rostral ventrolateral medulla of conscious and anesthetized rats

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dc.contributor.authorLacerda, J.e.c. [UNIFESP]
dc.contributor.authorCampos, Ruy Ribeiro [UNIFESP]
dc.contributor.authorAraujo, G.c. [UNIFESP]
dc.contributor.authorAndreatta-van Leyen, S. [UNIFESP]
dc.contributor.authorLopes, Oswaldo Ubriaco [UNIFESP]
dc.contributor.authorGuertzenstein, P.g. [UNIFESP]
dc.contributor.institutionUniversidade Federal de São Paulo (UNIFESP)
dc.date.accessioned2015-06-14T13:30:07Z
dc.date.available2015-06-14T13:30:07Z
dc.date.issued2003-09-01
dc.description.abstractThe rostral ventrolateral medulla (RVLM) contains neurons involved in tonic and reflex control of arterial pressure. We describe the effects of gamma-aminobutyric acid (GABA) and anesthetics injected into the RVLM of conscious and urethane (1.2 g/kg, iv) anesthetized Wistar rats (300-350 g). In conscious rats, bilateral microinjection of GABA (50 nmol/200 nl) induced a small but significant decrease in blood pressure (from 130 ± 3.6 to 110 ± 5.6 mmHg, N = 7). A similar response was observed with sodium pentobarbital microinjection (24 nmol/200 nl). However, in the same animals, the fall in blood pressure induced by GABA (from 121 ± 8.9 to 76 ± 8.8 mmHg, N = 7) or pentobarbital (from 118 ± 4.5 to 57 ± 11.3 mmHg, N = 6) was significantly increased after urethane anesthesia. In contrast, there was no difference between conscious (from 117 ± 4.1 to 92 ± 5.9 mmHg, N = 7) and anesthetized rats (from 123 ± 6.9 to 87 ± 8.7 mmHg, N = 7) when lidocaine (34 nmol/200 nl) was microinjected into the RVLM. The heart rate variations were not consistent and only eventually reached significance in conscious or anesthetized rats. The right position of pipettes was confirmed by histology and glutamate microinjection into the RVLM. These findings suggest that in conscious animals the RVLM, in association with the other sympathetic premotor neurons, is responsible for the maintenance of sympathetic vasomotor tone during bilateral RVLM inhibition. Activity of one or more of these premotor neurons outside the RVLM can compensate for the effects of RVLM inhibition. In addition, the effects of lidocaine suggest that fibers passing through the RVLM are involved in the maintenance of blood pressure in conscious animals during RVLM inhibition.en
dc.description.affiliationUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de Fisiologia
dc.description.affiliationUnifespUNIFESP, EPM, Depto. de Fisiologia
dc.description.sourceSciELO
dc.format.extent1269-1277
dc.identifierhttp://dx.doi.org/10.1590/S0100-879X2003000900019
dc.identifier.citationBrazilian Journal of Medical and Biological Research. Associação Brasileira de Divulgação Científica, v. 36, n. 9, p. 1269-1277, 2003.
dc.identifier.doi10.1590/S0100-879X2003000900019
dc.identifier.fileS0100-879X2003000900019.pdf
dc.identifier.issn0100-879X
dc.identifier.scieloS0100-879X2003000900019
dc.identifier.urihttp://repositorio.unifesp.br/handle/11600/1838
dc.identifier.wosWOS:000185667100019
dc.language.isoeng
dc.publisherAssociação Brasileira de Divulgação Científica
dc.relation.ispartofBrazilian Journal of Medical and Biological Research
dc.rightsinfo:eu-repo/semantics/openAccess
dc.subjectVasomotor toneen
dc.subjectVentrolateral medullaen
dc.subjectRVLMen
dc.subjectGABAen
dc.subjectConscious ratsen
dc.titleCardiovascular responses to microinjections of GABA or anesthetics into the rostral ventrolateral medulla of conscious and anesthetized ratsen
dc.typeinfo:eu-repo/semantics/article
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