Efeitos do exercício físico sobre as propriedades morfológicas e mecânicas de miócitos cardíacos de ratos diabéticos / Effects of exercise on the morphological and mechanical properties of cardiac myocytes from diabetic rats

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

30/04/2010

RESUMO

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 (~25C). 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.

ASSUNTO(S)

ciencias da saude exercício físico cardiomiócitos cardiomiopatia diabética diabetic cardiomyopathy cardiac myocytes exercises

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