Quantificação de capilares no tecido muscular esquelético em animais com insuficiência arterial periférica induzida submetidos a treinamento de endurance

Abstract

OBJETIVO: Analisar quantitativamente o tecido muscular esquelético de ratos com insuficiência arterial periférica induzida após treinamento de endurance. MÉTODOS: Os animais foram preparados cirurgicamente para a oclusão total da artéria femoral direita. Após o procedimento cirúrgico os ratos foram limitados a atividades na própria gaiola (sedentários, n = 10) ou submetidos a treinamento de endurance com ciclo ergômetro de forma contínua (treinados, n = 10), que consistia em caminhada 2x/dia (manhã e tarde) a 17 m/min, por 5 minutos, 5 dias/semana por 8 e 12 semanas. Os grupos foram subdivididos com seus respectivos grupos sedentários. A análise foi realizada pela observação histológica do músculo vasto medial direito após o período de teste. RESULTADOS: No grupo de animais treinados durante 8 semanas, o número médio de capilares no tecido muscular foi maior (5,2 ± 3,834) do que no grupo sedentário (0,6 ± 0,894). No grupo de animais treinados durante 12 semanas o número médio de capilares foi maior (6,8 ± 3,033) do que no grupo sedentário (3,0 ± 2,345). O número médio de capilares entre os grupos treinados de 12 e 8 semanas também foi maior no primeiro, entretanto, não estatisticamente significante. O número médio de capilares do grupo sedentário de 12 semanas foi maior (3,0 ± 2,345) do que no grupo de 8 semanas (0,6 ± 0,894). CONCLUSÃO: Em animais com insuficiência arterial periférica induzida submetidos a treinamento de endurance, há um processo de adaptação muscular com um aumento no número de capilares.

The effect of endurance training on the neovascularization of skeletal musculature

“…The present study, obtained from the experimental model used to analyze the number of capillaries in the skeletal muscular tissue of animals with induction of peripheral arterial insufficiency, shows results consistent with the literature, using animals of laboratory subjected to endurance training 3,11,13,15,16,17 . With the occlusion of the femoral artery, were created acute signals of peripheral arterial insufficiency, characterized by the unsuitable blood flow for the involved musculature.…”

“…Thus, the flow reserve for the right inferior member was decreased, however, the ability of collateral distal flow for this member remains sufficient to supply the basic tissue needs of muscular groups, and does not produce signals of ischemia at rest and/or tissue necrosis. It has been experimentally demonstrated that physical exercise increases the circulation, the capillarity and the functional ability of analyzed animals 3,11,13,15,16,17 . Physical exercise in humans also induces the vascular adaptations that improve the blood flow of skeletal musculature 18,19,20 .…”

“…This physiologic adaptation must decrease the distance of diffusion between the capillaries and mitochondria, prolonging the time of transit of erythrocytes and increasing the area of surface for the change of nutrients between the microcirculation and the myocytes 13,19 . Carvalho e col. 11 also subjected rats to endurance training during 8 and 12 weeks after the occlusion of femoral artery. They observed that from the eighth week of training, occurred an increase of number of capillaries that got on up to 12 weeks, although there was not difference when the two trained groups were compared.…”

“…It has been demonstrated that injured skeletal muscle can induce these process, as well as hypoxia; although this one does not appear as a demand to angiogenesis occur 7 . The hypothesis that physical exercise causes increase of capillarization in muscular tissue has been demonstrated in various experimental studies 8,9,10,11 and in human beings 12 . A previous study in rats subjected to bilateral femoral artery ligation 13 , causing peripheral arterial insufficiency, showed that blood circulation of all calf, so the proximal component as the distal segment, was significant higher in the group of trained animals.…”

“…This includes the collateral-dependent circulation for the tissues of trained animals, which was approximately 70% higher than the ones of sedentary group. Besides that, the experimental study in rats with endurance training during eight weeks was effective to cause an increase of average number of capillaries in skeletal muscular tissue, although this effect was more evident after twelve weeks of training 11 . However, it was not determined if this effect was progressive in the increase of number of capillaries in an intermediate phase between the two analyzed periods of training.…”