Efeitos do exercício físico sobre as propriedades morfológicas e mecânicas de miócitos cardíacos de ratos diabéticos
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2010-04-30
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Universidade Federal de Viçosa
Resumo
O objetivo do presente estudo foi verificar os efeitos de um programa de natação (PN) sobre as propriedades mecânicas e morfológicas de miócitos cardíacos das regiões do subepicárdico( EPI) e endocárdio (ENDO) do ventrículo esquerdo (VE) de ratos com diabetes experimental. Ratos (Rattus novergicus) da linhagem Wistar com trinta dias de idade (massa corporal 250g) foram submetidos à injeção intraperitoneal de estreptozotocina (STZ, 60mg/kg de massa corporal) diluída em 1mL de tampão citrato de sódio (0,1 M, pH 4.5) ou a mesma dose de tampão citrato de sódio (0,1 M, pH 4.5). Aqueles com glicemia acima de 300 mg/dL foram distribuídos aleatoriamente em diabéticos sedentários (DS, n=20) e diabéticos exercitados (DE, n=20). Os animais que não receberam STZ foram separados em controle não diabéticos (CN, n=10) e controle não diabéticos exercitados (CNE, n=10). Após 45 dias dehiperglicemia os animais DE e os CNE foram submetidos a um PN (5 dias/semana, 90 min/dia), por 8 semanas. Após eutanásia, o coração foi removido e os miócitos das regiões do sub-epicárdio (EPI) e sub-endocárdio (ENDO) do VE foram isolados e estimulados eletricamente a 1 e 3 Hz em temperatura ambiente (~25ºC). O diabetes experimental reduziu o peso corporal, o peso relativo dos ventrículos e o comprimento da tíbia. O PN não alterou o peso corporal e a glicemia nos animais dos grupos experimentais, mas aumentou o peso relativo dos ventrículos tanto nos animais diabéticos quanto nos controles não diabéticos. Não houve diferenças regionais (EPI vs ENDO) significativas nas propriedades morfológicas e mecânicas em resposta ao diabetes e ao PN. O diabetes experimental reduziu o comprimento, a largura e o volume dos cardiomiócitos. O PN aumentou a largura e o volume dos cardiomiócitos, sem alterar seu comprimento, nos animais diabéticos apenas. A amplitude de contração celular foi reduzida pelo diabetes, mas o PN aumentou essa amplitude tanto nos animais diabéticos quanto nos não diabéticos. O diabetes prolongou o tempo de contração celular, entretanto, o PN reduziu esse tempo em animais diabéticos e não diabéticos. O diabetes prolongou o tempo de relaxamento celular, todavia, o PN reduziu este tempo nos animais diabéticos e nos não diabéticos. Concluiu-se que o PN alterou as propriedades morfológicas dos miócitos do VE de ratos com diabetes experimental e atenuou as disfunções mecânicas destes cardiomiócitos, sem distinção regional.
The aim of this study was to verify the effects of a swimming training (ST) on the morphological and mechanical properties of cardiac myocytes from different regions of the left ventricle (LV) of rats with experimental diabetes. One month old male Wistar rats (body mass ~ 250g) received an intraperitoneal injection of Streptozootocin (STZ, 60mg/kg body mass) diluted in 1 mL sodium citrate buffer (0, 1 M, pH 4.5) or the same dose of sodium citrate buffer (0, 1 M, pH 4.5). Those rats with blood glucose levels above 300 mg/dL were randomly divided into diabetic sedentary (DS, n=20) and diabetics exercised (DE, n=20). Age and body mass-matched animals served as control non diabetic (CN, n=10) and control non diabetic exercised (CNE, n=10). Animals from DE and CNE groups were submitted to a swimming program (SP) (5 days/week, 90 min/day), for 8 weeks. At sacrifice the heart was removed and myocytes from sub-epicardium (EPI) and sub-endocardium (ENDO) regions of the LV were isolated and stimulated at 1 and 3 Hz, at room temperature (~25ºC). Experimental diabetes reduced animals' body mass, relative LV mass and tibia length. The SP did not affect body mass and blood glucose levels, but increased the relative LV mass of diabetic and non diabetic animals. No regional differences (EPI vs ENDO) between morphological and mechanical properties were found in response to either diabetes or SP. However, diabetes reduced cell length, width, volume and amplitude of contraction, and prolonged the time course of cell contraction and relaxation. The SP increased cell width and volume of cardiac myocytes of diabetic rats without changing cell length. I addition increased the amplitude of contraction and reduced the time course of cell contraction and relaxation. It was concluded that the SP affected the morphological properties of LV myocytes from rats with experimental diabetes and attenuated the mechanical dysfunctions of this cells with no regional distinction.
The aim of this study was to verify the effects of a swimming training (ST) on the morphological and mechanical properties of cardiac myocytes from different regions of the left ventricle (LV) of rats with experimental diabetes. One month old male Wistar rats (body mass ~ 250g) received an intraperitoneal injection of Streptozootocin (STZ, 60mg/kg body mass) diluted in 1 mL sodium citrate buffer (0, 1 M, pH 4.5) or the same dose of sodium citrate buffer (0, 1 M, pH 4.5). Those rats with blood glucose levels above 300 mg/dL were randomly divided into diabetic sedentary (DS, n=20) and diabetics exercised (DE, n=20). Age and body mass-matched animals served as control non diabetic (CN, n=10) and control non diabetic exercised (CNE, n=10). Animals from DE and CNE groups were submitted to a swimming program (SP) (5 days/week, 90 min/day), for 8 weeks. At sacrifice the heart was removed and myocytes from sub-epicardium (EPI) and sub-endocardium (ENDO) regions of the LV were isolated and stimulated at 1 and 3 Hz, at room temperature (~25ºC). Experimental diabetes reduced animals' body mass, relative LV mass and tibia length. The SP did not affect body mass and blood glucose levels, but increased the relative LV mass of diabetic and non diabetic animals. No regional differences (EPI vs ENDO) between morphological and mechanical properties were found in response to either diabetes or SP. However, diabetes reduced cell length, width, volume and amplitude of contraction, and prolonged the time course of cell contraction and relaxation. The SP increased cell width and volume of cardiac myocytes of diabetic rats without changing cell length. I addition increased the amplitude of contraction and reduced the time course of cell contraction and relaxation. It was concluded that the SP affected the morphological properties of LV myocytes from rats with experimental diabetes and attenuated the mechanical dysfunctions of this cells with no regional distinction.
Descrição
Palavras-chave
Cardiomiopatia diabética, Cardiomiócitos, Exercício físico, Diabetic cardiomyopathy, Cardiac myocytes, Exercises
Citação
SILVA, Márcia Ferreira da. Effects of exercise on the morphological and mechanical properties of cardiac myocytes from diabetic rats. 2010. 86 f. Dissertação (Mestrado em Aspectos sócio-culturais do movimento humano; Aspectos biodinâmicos do movimento humano) - Universidade Federal de Viçosa, Viçosa, 2010.