Navegando por Palavras-chave "Sistema nervoso parassimpático"

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    Contribuição tônica do quimiorreflexo carotídeo para o controle vagal cardíaco no repouso, ortostatismo e durante a recuperação após o exercício em pacientes com hipertensão arterial pulmonar
    (Universidade Federal de São Paulo (UNIFESP), 2018-11-28) Ribeiro, Marcelle de Paula [UNIFESP]; Silva, Bruno Moreira [UNIFESP]; http://lattes.cnpq.br/6680100353729718; http://lattes.cnpq.br/7001582128466985; Universidade Federal de São Paulo (UNIFESP)
    Pulmonary Arterial Hypertension (PAH) is a rapidly progressive disease with multiple etiologies and an extremely poor prognosis. Patients with PAH present marked autonomic dysfunction, characterized by increase in sympathetic activity and reduction in vagal activity to cardiovascular system. The augmented peripheral chemoreflex responsiveness seems to play a role on autonomic dysfunction in PAH. However, remains unclear the tonic contribution of the peripheral chemoreflex to cardiac vagal control in PAH. We hypothesized that the carotid chemoreflex would impair the cardiac vagal control at rest and during orthostatic challenge in patients with PAH and this impairment would be increased during post-exercise recovery, since evidences have shown that the peripheral chemoreflex might be sensitized by different substances released during exercise. To test these hypothesis, 20 patients with established PAH and 13 age and sex matched healthy controls (CON) took part of the study. Both groups underwent to peripheral chemoreflex sensitivity evaluation through transient hypoxic inhalation. Afterwards, they were randomly exposed to 1) hyperoxia (carotid chemoreflex inhibition, 100% O2), or 2) normoxia (control session, 21% O2); during cardiac vagal modulation assessment (baroreflex sensitivity [BRS]; heart rate variability [HRV]; heart rate recovery [HRR]). Data are shown as mean ± SD and comparisons between gases and groups were acquired using the Mixed Linear Model (p ≤ 0.05). The PAH showed peripheral chemoreflex sensitivity to hypoxia compared to CON (P=0.01). During rest, hyperoxia increased vagal indexes of HRV and BRS in both PAH and CON groups, and this increase was similar among groups, indicating that the carotid chemoreflex tonically modulates the cardiac vagal control in healthy subjects and patients with PAH. During orthostatic challenge, hyperoxia increased BRS in both groups and this effect was greater in PAH, indicating that the carotid chemoreflex is sensitized in PAH and contributes to impaired BRS during orthostatic challenge in this group. During post-exercise recovery, hyperoxia increased HRR and HRV in both groups and this effect was greater in PAH, indicating that the carotid chemoreflex is sensitized in PAH and contributes to impaired post-exercise vagal reactivation in this group. Taking together, the results suggest that the carotid chemoreflex tonically modulate the cardiac vagal control in healthy humans and contributes to cardiac vagal dysfunction during orthostatism and during post-exercise recovery in patients with PAH.
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    Mecanismos neurais envolvidos nos ajustes hemodinâmicos promovidos pela pilocarpina em ratos tratados com agonistas e antagonistas adrenérgicos
    (Universidade Federal de São Paulo (UNIFESP), 2003) Moreira, Thiago dos Santos [UNIFESP]; Colombari, Eduardo [UNIFESP]
    A pilocarpina, uma droga classificada como um agonista colinergico muscarinico, age nas glandulas salivares, produzindo vasodilatacao e salivacao. Estudos recentes tem mostrado que grande parte da salivacao induzida pela pilocarpina depende de mecanismos cerebrais. A salivacao induzida pela pilocarpina pode ser inibida pela lesao de estruturas cerebrais anteriores, como a regiao anteroventral do terceiro ventriculo (AM), area septal (AS) ou hipotalamo lateral (HL). Um mecanismo inibitorio da salivacao induzida pela pilocarpina tambem muito estudado esta relacionado com receptores adrenergicos 2 e imidazolicos. A moxonidina, assim com a clonidina (agonistas adrenergicos 2 e imidazolicos), sao drogas anti-hipertensivas que quando administradas centralmente reduzem a salivacao induzida por pilocarpina. Alem de participarem do controle de mecanismos salivatorios, essas drogas tambem estao envolvidas na regulacao cardiovascular. Assim, foram objetivos deste trabalho: a) estudar as alteracoes hemodinamicas produzidas pela associacao de moxonidina (agonista de receptores adrenergicos 2 e imidazolicos) e -metil noradrenalina (agonista de receptores adrenergicos 2) injetada nos ventriculos cerebrais (ventriculo lateral - VL e quarto ventriculo - 4°V) sobre as respostas hemodinamicas produzidas pela pilocarpina (agonista colinergico) injetada no VL. b) investigar o papel dos receptores adrenergicos 2 nos efeitos hemodinamicos da associacao de moxonidina ou -metil noradrenalina injetada no VL ou 4° V seguido de pilocarpina no VL. Para tanto, foram utilizados ratos Wistar com canulas de aco inoxidavel implantadas nos ventriculos cerebrais: VL (volume de injecao 1 a 2 L) e/ou 4°V (volume de injecao 1 L). Os ratos foram anestesiados com uretana (1,2 g/kg, i.v.) e um cateter foi inserido na arteria femoral para registro de pressao arterial media (PAM) e frequencia cardiaca (FC). Sondas miniaturizadas foram posicionadas ao redor da arteria que irriga o complexo submandibular/sublingual, da arteria mesenterica superior, da arteria renal esquerda e da extremidade da aorta abdominal para registro de fluxo sanguineo pelo metodo da fluxometria Dopplera(au)