Alterações na biodisponibilidade de óxido nítrico e no estresse oxidativo em plaquetas de mulheres na pós-menopausa

• Autor(a) principal: Mury, Wanda Vianna
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/7859
• topic: Nitric oxide; Menopause; Blood platelet; Oxidative stress; Óxido nítrico; Menopausa; Plaqueta; Estresse oxidativo; Pós-Menopausa Metabolismo; Cardiopatias em mulheres; Óxido nítrico; Óxido nítrico sintase Metabolismo; Plaquetas (Sangue) Fisiopatologia; Arginina Metabolismo; CNPQ::CIENCIAS BIOLOGICAS::MORFOLOGIA

Cardiovascular risk is exponentially increased in women after menopause compared to women in reproductive age. This may be partially explained by an increased platelet activation and endothelial dysfunction. Platelet derived nitric oxide is essential for the inhibition of its activation and aggregation, and its bioavailability depends both on its synthesis and its scavenging by reactive oxygen species. Thus, our aim was to investigate L-arginine-nitric oxide signaling in platelets from postmenopausal women and its association with oxidative stress and platelet aggregation. Fifteen young women (control group) and 12 postmenopausal women without risk factors for cardiovascular diseases consented to participate in the study. Blood was collected in the fasting state in appropriate anticoagulant tubes for platelet experiments. Platelet aggregation induced by collagen was significantly increased in postmenopausal than in young women. They also showed an increased total L-arginine transport, despite lower plasma L-arginine levels. Platelet nitric oxide synthase activity was impaired in postmenopausal women, but no difference was observed in endothelial and inducible nitric oxide synthase expression between groups. The expression of 1 and 1 subunits of guanilate cyclase and phosphodiesterase V were similar between groups. The expressions of gp91phox and p47phox subunits of NADPH oxidase and glutathione peroxidase were not modified. On the other hand, there was an up-regulation of catalase protein levels. Superoxide dismutase activity, but not catalase nor glutathione peroxidase activities, was increased in climacteric women. It was also reported that sulfhydryl group content was increased in postmenopausal women. There was no difference in protein oxidative damage between groups. These findings may contribute to a better understanding of platelet hyperaggregation in postmenopausal women, which may help to further elucidate the heightened cardiovascular morbidity and mortality in this population.