Navegando por Palavras-chave "Adrenérgicos"

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    Papel dos receptores beta2-adrenérgicos na proteção de arritmias cardíacas induzidas em camundongos normais e hiperlipidêmicos
    (Universidade Federal de São Paulo (UNIFESP), 2013-12-20) Ternes, Simone Correia [UNIFESP]; Spadari, Regina Celia [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Hypercholesterolemia, hypertension and atherosclerosis are associated comorbidities with high incidence of cardiovascular events, including arrhythmias and sudden cardiac death. The genetic profile associated to a high fat diet can result in anatomical and functional cardiac changes that may lead to pathological events and remodeling of the β-adrenergic receptors population. The β1 and β2 adrenoceptor subtypes play different roles in regulating heart function and structure. While the β1 subtype plays pro-apoptotic and proarrhythmic effects mediated by its interaction with stimulatory G protein (Gs), β2 adrenoceptors play the opposite effect by coupling with inhibitory G protein (Gi). Thus, in vivo receptors activation or inactivation by drugs and simultaneous record electrocardiogram is an interesting method to evaluate its effects on cardiac rhythm and performance hemodynamic status. This study aims to evaluate in vivo the β-adrenoceptor subtypes involvement in the generation of cardiac arrhythmias in normal mice and mice treated with high-cholesterol diet. It also aims to develop a protocol for evaluation of these parameters in conscious mice. The results showed that feeding mice with high-cholesterol diet increased serum cholesterol concentrations, mean arterial blood pressure and heart rate, the autonomic modulation reversing on the heart, increasing responsiveness to the positive chronotropic effect of isoproterenol and to the blocking effect of the β2 adrenergic antagonist ICI118.551. Furthermore, it induced arrhythmia that was accentuated by the β2 adrenoceptor blockade. It is concluded that the present data show that feeding high-cholesterol diet induced hemodynamic changes and heart rhythm disturbances. Moreover, this data reinforce the specificity of roles played by both adrenoceptor subtypes in the generation and protection cardiac arrhythmias, showing a possible protective anti-arrhythmic role played by β2 subtype and suggesting a compensatory or adaptive remodeling of β-adrenergic receptors population induced by stress and/or chronic overload imposed on the heart. We also conclude that this experimental model is suitable for the study cardiovascular physiology and of drugs effect on cardiovascular parameters in mice.