Envelhecimento e exerc??cio de for??a exc??ntrico: responsividade do ??xido n??trico e influ??ncia do polimorfismo (Glu298Asp) da ??xido n??trico sintase endotelial

• Autor(a) principal: Teixeira, Tatiane Gomes
• Data de Publicação: 2014
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UCB
• Texto Completo: https://bdtd.ucb.br:8443/jspui/handle/tede/2037
• topic: Gen??tica; Obesidade; Envelhecimento; ??xido n??trico; Polimorfismo; Exerc??cio de For??a Exc??ntrico (EFE); Idoso; CIENCIAS DA SAUDE::EDUCACAO FISICA

Reduced nitric oxide (NO) bioavailability is involved in a number of cardiovascular, muscular and inflammatory mechanisms, mainly in the elderly; while physical exercise has been pointed as an important tool in preventing and minimizing the negative effects of aging. The present thesis comprises two studies that aimed 1) To investigate the influence of the endothelial nitric oxide synthase (eNOS) polimorphysm (Glu298Asp) on the acute response of NO to eccentric resistance exercise (ERE), and also on the biochemical markers, body composition and muscular strength of obese elderly women. 2) To identify the presence of subjects with low or high responsivity of NO to ERE, and the influence of distinct levels of responsivity on biochemical and inflammatory markers, body composition and muscular strength. Eighty-seven older women (69.4 ?? 6.1 years, 74.9 ?? 12.7 kg, heigh 151.9 ?? 6.0 cm and BMI 32.5 ?? 5.7 kg/m2) participated in the study. Forty-nine of them participated of the second study. The exercise protocol consisted of seven sets of ten eccentric repetitions at 110% of ten repetitions maximum (10RM) and the serum concentration of nitrite was measured immediately after and 3, 24 and 48 hours after the ERE. Results: The ERE elevated the serum concentration of nitrite, without a significative influence of eNOS polymorphism (study 1). The group of T allele carriers (TT or TG genotype) presented higher triglicerides (p=0.014), VLDL (p=0.025) and urea (p=0.038) concentrations, and lower body weight (p=0.013), BMI (p=0.031), prevalence of obesity (81% versus 56%) and relative muscle strength (p=0.047) as compared with the GG genotype carriers. Inter-individual differences were found in the magnitude of serum response of nitrite to ERE, which allowed the identification of low (LR) and high responsive (HR) groups (study 2). The LR group presented higher percentual body fat (p=0.017), total cholesterol (p=0.043) and LDL (p=0.044), and lower upper limb fat-free mass (p=0.054) as compared with the HR group. These results demonstrate that: a) in obese older women, nitrite concentration is elevated up to 48 h after ERE, and the magnitude is influenced by inter-individual variations, independently of eNOS polymorphism; b) the presence of the eNOS polymorphism Glu298Asp (TT or TG genotype) and the low responsivity of nitrite to ERE are indicative of unhealthier lipid profile and higher fat percentage in older obese women. Furthermore, these parameters can be used in clinical practice to improve the identification of the impairment degree during aging, as well for understanding the different responses to exercise.