Early remodeling of rat cardiac muscle induced by swimming training

Abstract

The aim of the present investigation was to study the effect of acute swimming training with an anaerobic component on matrix metallopeptidase (MMP) activity and myosin heavy chain gene expression in the rat myocardium. Animals (male Wistar rats, weighing approximately 180 g) were trained for 6 h/day in 3 sessions of 2 h each for 1 to 5 consecutive days (N = 5 rats per group). Rats swam in basins 47 cm in diameter and 60 cm deep filled with water at 33 to 35ºC. After the training period a significant increase (P < 0.05) was observed in the heart weight normalized to body weight by about 22 and 35% in the groups that trained for 96 and 120 h, respectively. Blood lactate levels were significantly increased (P < 0.05) in all groups after all training sessions, confirming an anaerobic component. However, lactate levels decreased (P < 0.05) with days of training, suggesting that the animals became adapted to this protocol. Myosin heavy chain-ß gene expression, analyzed by real time PCR and normalized with GAPDH gene expression, showed a significant two-fold increase (P < 0.01) after 5 days of training. Zymography analysis of myocardium extracts indicated a single ~60-kDa activity band that was significantly increased (P < 0.05) after 72, 96, and 120 h, indicating an increased expression of MMP-2 and suggesting precocious remodeling. Furthermore, the presence of MMP-2 was confirmed by Western blot analysis, but not the presence of MMP-1 and MMP-3. Taken together, our results indicate that in these training conditions, the rat heart undergoes early biochemical and functional changes required for the adaptation to the new physiological condition by tissue remodeling.

High molecular mass proteomics analyses of left ventricle from rats subjected to differential swimming training

“…A few morphologic alterations, such as a small sclerotic area with infiltration of granule lipofuscin, characterizing particular metabolic alterations, probably associated with overload were seen in TG 2 , (Additional file 1: Figure S1) [5,6]. This pigment is closely associated with oxygen-derived free radicals, which are an important component of muscle fatigue [7] indicating that TG 2 are inducing heart tissue modifications to the detriment of improvement in metabolism. On the other hand, microscopic morphology analysis in TG 3 indicated cellular hypertrophy, showing several modifications such as several areas with increased fibrosis (Additional file 1: Figure S1), evidencing a higher adaptation to exercise overload.…”

MMP−2 Expression in Skeletal Muscle after Strength Training

“…Additionally, the reduced tissue oxygenation promoted by highintensity resistance exercise may act as a potent physiological stimulus for fi ber type modifi cation (mainly type II) [ 6 ] . In a previous study from our laboratory, we showed that high intensity anaerobic exercise (eliciting high levels of blood lactate) could be an additional factor modifying gene expression of myocardium muscle [ 24 ] . In addition, high-intensity aerobic exercise induced an increase of MMP −2 activity in both type I and II fi berpredominant muscle groups [ 2 , 11 ] .…”

Natação e aspectos morfológicos do músculo esquelético em processo de reparo após criolesão

“…Verzola et al 17 utilizaram a natação para verificar a influência no remodelamento de miocárdio de ratos e evidenciaram benefícios desta terapia por meio de aumento na atividade da metaloprotease de matriz tipo 2 (MMP2). O treinamento utilizado consistia de sessões diárias com duração de 6 horas, realizadas em períodos de 3, 4 ou 5 dias consecutivos.…”

“…Os animais foram submetidos ao protocolo de natação em piscinas que consistiam de compartimentos de cloreto de polivinila (PVC) individuais com 24 cm de diâmetro, com água a 50 cm de profundidade e temperatura média de 33°C. Os animais nadaram por um período de 90 min/dia, 6 vezes por semana 16,17 , totalizando 3, 9 ou 15 sessões para os grupos 7, 14 e 21 dias, respectivamente. Durante todo o protocolo experimental, a água foi movimentada e os animais tiveram pesos fixados à cauda (até 20% do peso corporal) para evitar a flutuação e garantir, dessa forma, a realização do treinamento proposto.…”