Influência da obesidade sobre a composição de cadeias pesadas de Miosina e Fibrose intersticial miocárdica de ratos normotensos e espontaneamente hipertensos
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Data
2008-02-18
Autores
Oliveira Junior, Silvio Assis de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Tem sido demonstrado que a obesidade promove remodelação cardíaca em ratos. Este estudo investigou a influência da obesidade induzida por dieta hipercalórica (HP) sobre as variáveis nutricionais e o remodelamento cardíaco, considerando a hipertrofia, fibrose intersticial e composição de cadeias pesadas de miosina (MHC), em ratos normotensos Wistar Kyoto (WKY) e ratos espontaneamente hipertensos (SHR). Parcelas de SHR (20) e WKY (20) com 60 dias de idade foram distribuídas em quatro grupos: SHR-C, SHR-OB, WKY-C e WKY-OB. Os grupos C receberam uma dieta normocalórica (C, 3,15 Kcal/g) e os grupos OB foram tratados com uma dieta hipercalórica (4,5 Kcal/g) durante 20 semanas. Dois critérios foram adotados para refinar a composição dos grupos em referência à obesidade, baseados na ingestão alimentar e no peso corporal (PC). As determinações nutricionais incluíram ingestão calórica, eficiência alimentar, PC, adiposidade, glicemia e perfil lipidêmico. A pressão arterial sistólica (PAS) foi mensurada antes e após a intervenção dietética. As análises morfológicas abrangeram a pesagem dos átrios, ventrículos direito e esquerdo e o estudo da umidade procedeu-se em fragmentos cardíacos, hepáticos e pulmonares. Secções histológicas miocárdicas foram utilizadas para cálculo da área seccional do miócito (AM) e fração intersticial de colágeno (FIC). A composição relativa de MHCs foi determinada por eletroforese de gel de poliacrilamida duodecil sulfato de sódio. A composição dos grupos foi submetida à análise estatística pelo teste de proporções binomiais entre e dentro das populações. Algumas variáveis nutricionais e a PAS foram analisadas por MANOVA no modelo de medidas repetidas. Os demais dados foram avaliados por ANOVA e teste de Tukey. Uma interação vigente entre linhagem e tratamento foi notada na composição dos grupos.
Obesity has been shown to induce cardiac remodeling in rats. In this study, we investigated the influence of obesity induced by high-fat diet (HFD) on nutritional variables and cardiac remodeling, concerning hypertrophy, interstitial fibrosis and myosin heavy chain composition, in normotensive Wistar Kyoto (WKY) and spontaneously hypertensive (SHR) rats. Sixty-day-old SHR (n=20) and WKY (n=20) were distributed into four groups: SHR-C, SHR-OB, WKY-C e WKY-OB. The C groups received a control diet (C, 3,15 Kcal/g) and the OB groups were treated with a HFD (4,5 Kcal/g) during 20 weeks. Two criteria were adopted to refine the groups composition in reference to obesity based on food consumption and body weight (BW). Nutritional determinations included energy intake, feed efficiency, BW, adiposity, glycemia and lipid profile. Systolic blood pressure (SBP) was measured before and after diet intervention. Morphological analysis involved atria, right and left ventricles weights and humidity study was realized with cardiac, liver and lung pieces. Using myocardial histological sections, myocyte cross sectional areas (MA) and collagen interstitial fraction (CIF) were measured. Relative myosin heavy chain (MHC) composition was determined using sodium dodecyl sulfatepolyacrylamide gel electrophoresis. The groups compositions were submitted to statistical analysis by the binomial proportional test between and within populations. Some nutritional variables and SBP were analyzed by two-way MANOVA in repeated measures model. Other data were evaluated by two-way ANOVA and Tukey test. An interaction between strain and treatment was noted to groups composition. Alimentar efficiency was increased only in the WKYOB and glycemic tolerance was impaired in both OB groups. HFD induced an increase of BW (WKY-C 481.6±39.4 g; WKY-OB 611.4±48.2 g; p<0.05; SHRC 370.3±16.0 g; SHR-OB 410.8±9.3 g; p<0.05) and adiposity in both strains.
Obesity has been shown to induce cardiac remodeling in rats. In this study, we investigated the influence of obesity induced by high-fat diet (HFD) on nutritional variables and cardiac remodeling, concerning hypertrophy, interstitial fibrosis and myosin heavy chain composition, in normotensive Wistar Kyoto (WKY) and spontaneously hypertensive (SHR) rats. Sixty-day-old SHR (n=20) and WKY (n=20) were distributed into four groups: SHR-C, SHR-OB, WKY-C e WKY-OB. The C groups received a control diet (C, 3,15 Kcal/g) and the OB groups were treated with a HFD (4,5 Kcal/g) during 20 weeks. Two criteria were adopted to refine the groups composition in reference to obesity based on food consumption and body weight (BW). Nutritional determinations included energy intake, feed efficiency, BW, adiposity, glycemia and lipid profile. Systolic blood pressure (SBP) was measured before and after diet intervention. Morphological analysis involved atria, right and left ventricles weights and humidity study was realized with cardiac, liver and lung pieces. Using myocardial histological sections, myocyte cross sectional areas (MA) and collagen interstitial fraction (CIF) were measured. Relative myosin heavy chain (MHC) composition was determined using sodium dodecyl sulfatepolyacrylamide gel electrophoresis. The groups compositions were submitted to statistical analysis by the binomial proportional test between and within populations. Some nutritional variables and SBP were analyzed by two-way MANOVA in repeated measures model. Other data were evaluated by two-way ANOVA and Tukey test. An interaction between strain and treatment was noted to groups composition. Alimentar efficiency was increased only in the WKYOB and glycemic tolerance was impaired in both OB groups. HFD induced an increase of BW (WKY-C 481.6±39.4 g; WKY-OB 611.4±48.2 g; p<0.05; SHRC 370.3±16.0 g; SHR-OB 410.8±9.3 g; p<0.05) and adiposity in both strains.
Descrição
Palavras-chave
Obesidade, Hipertensão arterial, Essential arterial hypertension, Obesity, Cardiac remodeling
Como citar
OLIVEIRA JUNIOR, Silvio Assis de. Influência da obesidade sobre a composição de cadeias pesadas de Miosina e Fibrose intersticial miocárdica de ratos normotensos e espontaneamente hipertensos. 2008. 114 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Medicina de Botucatu, 2008.