O treinamento físico aeróbio corrige a rarefação capilar e as alterações nas proporções dos tipos de fibra muscular esquelética em ratos espontaneamente hipertensos

Abstract

Aerobic exercise training (ET) has been established as an important non-pharmacological treatment of hypertension, since it decreases blood pressure. Studies show that the skeletal muscle abnormalities in hypertension are directly associated with capillary rarefaction, higher percentage of fast-twitch fibers (type II) with glycolytic metabolism predominance and increased muscular fatigue. However, little is known about these parameters in hypertension induced by ET. We hypothesized that ET corrects capillary rarefaction, potentially contributing to the restoration of the proportion of muscle fiber types and metabolic proprieties. Twelve-week old Spontaneously Hypertensive Rats (SHR, n=14) and Wistar Kyoto rats (WKY, n=14) were randomly assigned into 4 groups: SHR, trained SHR (SHR-T), WKY and trained WKY (WKY-T). As expected, ten weeks of ET was effective in reducing blood pressure in SHR-T group. In addition, we analyzed the main markers of ET. Resting bradycardia, increase of exercise tolerance, peak oxygen uptake and citrate synthase enzyme activity in trained groups (WKY-T and SHR-T) showed that the aerobic condition was achieved. ET also corrected the skeletal muscle capillary rarefaction in SHR-T. In parallel, we observed reduction in percentage of type IIA and IIX fibers and simultaneous augmented percentage of type I fibers induced by ET in hypertension. These data suggest that ET prevented changes in soleus fiber type composition in SHR, since angiogenesis and oxidative enzyme activity increased are important adaptations of ET, acting in the maintenance of muscle oxidative metabolism and fiber profile.

Morphofunctional characteristics of skeletal muscle in rats with cerebral palsy

“…To obtain the capillary‐to‐fibre ratio, muscle fibres covering the upper right margins were included in the count, while those found in the lower left margins were excluded from the analysis in order to minimize errors, since capillaries present in the microscopic fields belonged to the vascularization of all fibres, including those that were not complete in the image. Quantification was performed individually by two trained evaluators, and the mean of the two values was used for analysis …”

Comentário sobre: Wang Lijun, MicroRNAs no coração e na circulação durante o exercício físico

“…In Brazil, SAH affects more than 30% of the adult population, with prevalence among the elderly exceeding 60% [17]. The role of regular physical exercise stands out as a non-pharmacological measure for the treatment of SAH, since, can act by reducing sympathe-tic nervous activity (ANS) [18], decreasing capillary rarefaction, which increases the cross-sectional area of capillaries [19]. These two physiological adaptations together contribute to the reduction of peripheral vascular resistance, consequently, reducing blood pressure values.…”