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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

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Previous issue date: 2014-12-03 / 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. / A redu????o da biodisponibilidade de ??xido n??trico (NO) est?? envolvida em in??meros
mecanismos cardiovasculares, musculares e inflamat??rios, principalmente na
popula????o idosa; enquanto o exerc??cio f??sico tem sido apontado como importante
estrat??gia para prevenir e minimizar os efeitos delet??rios do envelhecimento. A
presente tese ?? composta por dois estudos quantitativos, de delineamento quaseexperimental,
que objetivaram 1) Investigar a influ??ncia do polimorfismo (Glu298Asp)
da ??xido n??trico sintase endotelial (eNOS) sobre a resposta aguda do NO ao
exerc??cio de for??a exc??ntrico (EFE), bem como sobre os marcadores bioqu??micos, a
composi????o corporal e a for??a muscular de idosas obesas; 2) Identificar a presen??a
de idosas com alta ou baixa responsividade do NO ao EFE, e a influ??ncia dos
distintos graus de responsividade sobre os marcadores bioqu??micos, inflamat??rios,
composi????o corporal e for??a muscular. Participaram do primeiro estudo 87 idosas
(69,4 ?? 6,1 anos, 74,9 ?? 12,7 kg, estatura 151,9 ?? 6,0 cm e IMC 32,5 ?? 5,7 kg/m2), 49
das quais compuseram a amostra do segundo estudo. As volunt??rias completaram
sete s??ries de 10 repeti????es exc??ntricas a 110% de 10 repeti????es m??ximas (10RM),
sendo a concentra????o s??rica de nitrito medida imediatamente ap??s e 3, 24 e 48
horas ap??s o EFE. Resultados: o EFE provocou eleva????o da concentra????o de nitrito,
sem influ??ncia significativa do polimorfismo da eNOS (estudo 1). As carreadoras do
alelo T apresentaram maior concentra????o de triglicer??deos (p=0,014), VLDL
(p=0,025) e ureia (p=0,038), e menor peso corporal total (p=0,013), IMC (p=0,031),
preval??ncia de obesidade (81% versus 56%) e for??a muscular relativa (p=0,047) em
compara????o ??s idosas com gen??tipo GG. Foram encontradas diferen??as interindividuais
na magnitude de aumento do nitrito p??s-EFE, o que permitiu a
identifica????o de grupos pouco (PR) e muito responsivos (MR) (estudo 2). Idosas PR
apresentaram maior percentual de gordura (p=0,017), colesterol total (p=0,043) e
LDL (p=0,044), e menor massa livre de gordura de membros superiores (p=0,045)
em compara????o ??s MR (estudo 2). Estes resultados demonstram que: a) a
concentra????o de nitrito em idosas obesas se eleva at?? 48 horas ap??s o EFE, sendo
a magnitude influenciada por varia????es inter-individuais, independentemente do
polimorfismo da eNOS; b) a presen??a do polimorfismo Glu298Asp eNOS (gen??tipo
TT ou TG) e a baixa responsividade do nitrito ao EFE s??o indicativos de piores perfil
lip??dico e percentual de gordura corporal em idosas obesas. Sendo assim, estes
par??metros podem ser utilizados na pr??tica cl??nica para melhorar a identifica????o do
grau de acometimento durante o envelhecimento, bem como para entendimento das
diferentes respostas ao exerc??cio.

Identiferoai:union.ndltd.org:IBICT/oai:bdtd.ucb.br:tede/2037
Date03 December 2014
CreatorsTeixeira, Tatiane Gomes
ContributorsPrestes, Jonato
PublisherUniversidade Cat??lica de Bras??lia, Programa Strictu Sensu em Educa????o F??sica, UCB, Brasil, Escola de Sa??de e Medicina
Source SetsIBICT Brazilian ETDs
LanguagePortuguese
Detected LanguageEnglish
Typeinfo:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis
Formatapplication/pdf
Sourcereponame:Biblioteca Digital de Teses e Dissertações da UCB, instname:Universidade Católica de Brasília, instacron:UCB
Rightsinfo:eu-repo/semantics/openAccess
Relation6095716513072507778, 500, 500, 600, 3870802503144686128, 5178284805913411594

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