Efeitos do tratamento crônico com tamoxifeno sobre a reatividade vascular do leito coronariano de ratas espontaneamente hipertensas

• Main Author: Borgo, Mariana Veronez
• Publication Date: 2009
• Format: Master thesis
• Language: por
• Source: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Download full: http://repositorio.ufes.br/handle/10/7943
• topic: Tamoxifen; Estrogen; Hypertension; Vascular reactivity; Tamoxifeno; Estrogênio; Hipertensão; Reatividade vascular; Fisiologia; 612

Epidemiologic studies have demonstrated a decreased incidence of cardiovascular disease and risk factors in pre-menopausal women when compared with postmenopausal women. These results may be related, at least in part, with a significant decrease in the release of estrogen in menopause. Hormone reposition therapy (HRT) benefits metabolic and vascular factors, reducing the incidence of cardiovascular diseases. However, clinical trials are controversial as to their effects augmenting clinical interest over different replacement therapy low dose estrogen. Tamoxifen is a non-steroidal agent classified as a selective estrogen receptor modulator (SERM) for its specific actions, acting as an agonist or antagonist of estrogen receptors in deferent tissues. It is used as adjuvant therapy in estrogen dependent breast cancer, mostly in post-menopausal patients; however the cardiovascular effects of this drug have not been totally elucidated. The goal of this study is to identify the chronic tamoxifen effects on the blood pressure, cardiac function and coronary vascular reactivity. SHR rats were divided in four groups: control (SC), tamoxifen treated (ST), ovariectomized control (SOC) and ovariectomized tamoxifen treated (SOT). The animals were treated during 90 days using the gavage method. BP, HR, dP/dTmax and coronarian vascular reactivity, in Langendorff method isolated hearts were evaluated. The results demonstrated that tamoxifen attenuates the elevated blood pressure present in ovariectomized animals (SOC), reduces heart rate (HR) and the cardiac contractility index (dP/dTmax). Coronary vascular reactivity was also affected with reduced vasoconstriction to acetilcoline and increased vasodilation to adenosine. These results show the importance of the potential benefic effects of tamoxifen over coronarian vascular reactivity through mechanisms that may contribute to the protection against cardiovascular diseases and their risk factors.