Detalhes bibliográficos
| Ano de defesa: |
2017 |
| Autor(a) principal: |
Mendonça, Michelle Mendanha
 |
| Orientador(a): |
Custódio, Carlos Henrique Xavier
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| Banca de defesa: |
Custódio, Carlos Henrique Xavier,
Pobbe, Roger Luís Henschel,
Costa, Renata Mazaro e |
| Tipo de documento: |
Dissertação
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| Tipo de acesso: |
Acesso aberto |
| Idioma: |
por |
| Instituição de defesa: |
Universidade Federal de Goiás
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| Programa de Pós-Graduação: |
Programa de Pós-graduação em Biologia (ICB)
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| Departamento: |
Instituto de Ciências Biológicas - ICB (RG)
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| País: |
Brasil
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| Palavras-chave em Português: |
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| Palavras-chave em Inglês: |
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| Área do conhecimento CNPq: |
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| Link de acesso: |
http://repositorio.bc.ufg.br/tede/handle/tede/8808
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Resumo: |
Within the hypothalamic areas involved in the control of cardiovascular function, neurons of the paraventricular hypothalamus play a key role, either by projecting to the sympathetic premotor neurons of rostroventrolateral medulla (RVLM) or by reaching preganglionic neurons of the spinal intermediolateral column (IML). Despite describing the role of PVH in the cardiovascular control, literature lacks of data on the PVH contribution to the control of cardiac function. In this regard, the aim of the present study was to assess whether gabaergic and adrenergic synapses, known for being active at the PVH, are involved in the control of cardiac function by its neurons in normotensive anesthetized animals. Experiments were performed in adult male Wistar rats (250-350g) that were anesthetized with urethane (1.2-1.4 g/kg i.p.) and underwent catheterization of femoral to record arterial pressure and heart rate. Femoral vein was used to inject the vasoactive drugs phenylephrine (10μg/kg) the sodium nitroprussiate (10μg/kg), the blocker of cardiac pacemaker zatebradine (1mg/kg) and to supplement anesthesia. The cardiac left ventricle was catheterized to record the left ventricular pressure and its derivative. Craniotomy allowed for injections into the PVH of: muscimol (20mM – 100nL), bicuculline (0,4mM - 100nL), propranolol (10mM – 100nL), isoproterenol (100μM – 100nL), fentolamine (13mM – 100nL), phenylephrine (30nM – 100nL). The main results were: i) inhibition of PVH by injecting GABAA agonist muscimol, reduced arterial pressure and cardiac inotropy; ii) disihibition of PVH neurons by injecting bicuculline evoked positive chronotropy and inotropy; iii) Alfa adrenergic receptors control cardiac function; iv) Beta adrenergic receptors of PVH do not influence cardiac function; v) afterload seems to poorly contribute to the PVH-evoked inotropy. Jointly, our results suggest that PVH provides substantial contribution to the tonic control of cardiac function. We conclude that the PVH participates in the control of cardiac function. Changes in the activity of these neurons by gabaergic and adrenergic influences may set autonomic control of cardiac function, thus resulting in contractile and heartbeat responses. Deepen the knowledge on the mechanisms underlying the control of central areas and its influence on the cardiovascular system may feed the understanding of cardiovascular pathophysiology. |
