RESUMO
Our aim was to evaluate whether endothelial overexpressing of the bradykinin B1 receptor could be associated with altered left ventricular and myocardial performance. Echocardiography and hemodynamic were employed to assess left ventricular morphology and function in Sprague Dawley transgenic rats overexpressing the endothelial bradykinin B1 receptor (Tie2B1 rats). The myocardial inotropism was evaluated on papillary muscles contracting in vitro. In Tie2B1 animals, an enlarged left ventricular cavity and lower fractional shortening coupled with a lower rate of pressure change values indicated depressed left ventricular performance. Papillary muscle mechanics revealed that both Tie2B1 and wild-type rat groups had the same contractile capacities under basal conditions; however, in transgenic animals, there was accentuated inotropism due to post-pause potentiation. Following treatment with the Arg(9)-BK agonist, Tie2B1 papillary muscles displayed a reduction in myocardial inotropism. Endothelial B1 receptor overexpression has expanded the LV cavity and worsened its function. There was an exacerbated response of papillary muscle in vitro to a prolonged resting pause, and the use of a B1 receptor agonist impairs myocardial inotropism.
Assuntos
Células Endoteliais/metabolismo , Contração Miocárdica , Músculos Papilares/metabolismo , Receptor B1 da Bradicinina/metabolismo , Disfunção Ventricular Esquerda/metabolismo , Função Ventricular Esquerda , Animais , Predisposição Genética para Doença , Masculino , Músculos Papilares/fisiopatologia , Fenótipo , Ratos Sprague-Dawley , Ratos Transgênicos , Receptor B1 da Bradicinina/genética , Regulação para Cima , Disfunção Ventricular Esquerda/genética , Disfunção Ventricular Esquerda/fisiopatologia , Remodelação VentricularRESUMO
The xylazine-ketamine mixture (KX) is an anesthetic approach commonly administered to assess cardiovascular function in rodents. This study aimed to examine if the cardiovascular and thermoregulatory effects of KX could persist after the anesthetic state ceased in rats. Male Wistar rats were anesthetized with K (50mg/kg) X (10mg/kg) through the intra-peritoneal route. Hemodynamic and thermoregulatory repercussions were evaluated in animals in awake state, during an anesthetic depth and after complete recovery of anesthetized state. KX was efficient to significantly induce deep anesthesia in all rats after 10min. A complete recovery of anesthetized state was observed only after 210min. Compared with preanesthetic state and control animals that received no drug, KX induced a significant reduction of systolic and diastolic blood pressure at 10min. Hypotension was more prominent at 150min. The heart rate was also significantly reduced after 10 min of KX and the highest magnitude of bradycardia was observed at 30min. In addition, rectal temperature was markedly decreased at 30min of KX and the higher reduction occurred at 150min. The hemodynamic and thermoregulatory effects of KX were maintained even after complete anesthetic recovery.
Objetivou-se com este estudo avaliar a persistência dos efeitos cardiovasculares e termorregulatórios da associação cetamina e xilasina (CX) mesmo após o período anestésico em ratos. Ratos Wistar machos foram anestesiados com cetamina 50mg/kg e xilasina 10mg/kg, por via intra-peritoneal. As repercussões hemodinâmica e termorregulatória foram avaliadas com os animais acordados, durante o período anestésico e após recuperação completa da anestesia. A CX foi eficiente em induzir significante regime anestésico em todos os ratos após 10min. A recuperação completa do estado de anestesia foi observada somente após 210min. Comparado com o estado pré-anestésico e com animais controles, que não receberam anestesia, a CX induziu significativa redução das pressões sistólica e diastólica aos 10min. A hipotensão foi mais evidente aos 150min após CX. A frequência cardíaca também foi significativamente reduzida com 10min de CX e a bradicardia foi mais acentuada aos 30min. A temperatura retal foi reduzida aos 30min, sendo mais acentuada após 150min de anestesia. Os efeitos hemodinâmicos e termorregulatórios da CX persistem mesmo após completa recuperação anestésica.
