Participação dos núcleos da rafe nas respostas cardiorespiratórias à hipóxia e hipercarbia em sapos / Role of the raphe nuclei in the ventilatory and cardiovascular response to hypoxia and hipercarbia in toads

AUTOR(ES)

Carolina Ribeiro Noronha de Souza

DATA DE PUBLICAÇÃO

2010

RESUMO

The raphe nuclei are brainstem cell groups and the main cell type is serotonergic. In adult anurans electrical or chemical stimulation of the medullary raphe has no effect on ventilation, whereas in mammals depending on the specific site of stimulation, an excitatory or inhibitory response is elicited. In mammals the medullary raphe participate in the ventilatory and cardiovascular response to hypoxia and hipercarbia while in amphibians there are no data available. Thus the present study was designed to investigate whether the raphe nuclei of toads (Rhinella schneideri) participate in the ventilatory and cardiovascular response to hypoxia (5% O2) and hipercarbia (5% CO2). First the raphe nuclei were located and identified. Fosrelated immunoreactivity was used to verify whether the raphe nuclei are activated or inhibited by hypoxia or hypercarbia. In addition, the role of raphe magnus and pontis in the respiratory and cardiovascular responses to hypoxia and hypercarbia were investigated by nonselective lesioning with ibotenic acid. Pulmonary ventilation was directly measured by pneumotachographic method and the arterial pressure by a femoral catheter. The results indicate that the medullary raphe nuclei are inhibited after hypoxic and hypercarbic stimulus (2,5h). Hypoxia caused hyperventilation and increase in the cardiac frequency in the vehicle and lesioned groups. Hypercarbia caused hyperventilation in both groups. Chemical lesions in the raphe magnus and pontis did not affect ventilatory or cardiovascular variables under resting conditions (normoxic normocárbica) or during the response to hypoxia or hipercarbia.

ASSUNTO(S)

cardiovascular response ventilation ventilação núcleos da rafe toads. resposta cardiovascular hipercarbia hypoxia raphe nuclei sapos. hypercarbia hipóxia

Documentos Relacionados

• Role of the raphe nuclei in the homeostatic responses to blood volume alteration : an immunohistochemical study of Fos expression in rats
• Estudo comparativo da expressão da proteína Fos nos núcleos da rafe entre ratos submetidos a exercício físico e sedentários
• The role of adenosine in the respiratory and cardiovascular response to systemic hypoxia in the rat.
• The human ventilatory response to stimulation by transient hypoxia.
• A dynamic analysis of the ventilatory response to hypoxia in man.