Avaliação cardiovascular e respiratória de ratas ooforectomizadas submetidas a hipertensão arterial pulmonar induzida pela monocrotalina

• Ano de defesa: 2010
• Autor(a) principal: Gava, Pablo Lúcio
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Mestrado em Ciências Fisiológicas; Centro de Ciências da Saúde; UFES; Programa de Pós-Graduação em Ciências Fisiológicas
• Palavras-chave em Português: Ooforectomy; Pulmonary arterial hypertension; Monocrotaline; Cardiovascular reflexes; Ooforectomia; Hipertensão arterial pulmonar; Monocrotalina; Reflexos cardiovasculares; Fisiologia; 612
• Link de acesso: http://repositorio.ufes.br/handle/10/7952

Pulmonary arterial hypertension (PAH) induced by monocrotaline (MCT) constitutes the pathophysiological conditions that involve several cardiovascular, respiratory and autonomic changes. Previous experimental model studies suggest that female sex hormones provide protective effects in the development of PAH. However, effects arising from the deficiency of these hormones on the PAH remain to be elucidated. The aims of the present study were to evaluate the possible hemodynamic, morphological, respiratory and gasometrical changes arising from PAH in female rats submitted to ooforectomy and shamoperated. Wistar female rats were used (200-220 g) and divided into 4 groups: control (CON), MCT, OVX and OVX+MCT. Rats were submitted to OVX or SHAM, and 10 days later, received a single injection of MCT (60 mg/kg, SC), or the same volume of saline (~0.8 mL). After 4 weeks, recordings of cardiovascular, respiratory, gasometric were made and pulmonary histology. The results showed a significant increase of the dry and wet weight of the right ventricle, as well as pulmonary index in MCT groups, compared to respective control groups. We also observed that MCT groups showed values significantly higher of the peak systolic pressure (PSmax) of VD in relation to the respective control group. These findings were also observed in relation to the OVX group and the respective control group. The morphological analysis showed a marked thickening of the media layer of the distal branches of the pulmonary artery in the MTC groups. In relation to autonomic evaluation, we observed a significant increase of a sympathetic component, as well as an attenuation of the parasympathetic component in the MCT, OVX and OVX+MCT groups. For the respiratory parameters, we observed an increase of the alveolar ventilation in the MCT group, while OVX+MCT group showed an attenuation of this parameter. Gasometric evaluation showed that MCT groups present a reduction in the partial pressure of O2 (PaO2) and reduction of the percentage of the hemoglobin saturation (% Sat Hb) when compared to respective control groups, but OVX+MCT group showed an attenuation of the %Sat Hb when compared to MCT. In relation to cardiovascular reflexes, we observed an attenuation of the baroreflex 17 gain in the MCT groups and also a higher reduction in the OVX+MCT group compared to MCT. In the Bezold-Jarisch reflex evaluation, we observed an attenuation of the hypotensive responses in the MCT groups, but only in OVX+MCT group was an attenuation of the bradicardic responses observed. These data suggest that MCT produces important cardiovascular, autonomic, morphological, respiratory and gasometric changes, which are worsened by ooforectomy. Therefore, these results indicate that female sex hormones play an important protective function in this model of PAH.