Effects of combined physical training on arterial stiffness of dexamethasone-treated rats

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Arterial stiffness, determined by pulse wave velocity (PWV) has been considered an important cardiovascular risk predictor. It has been shown that high arterial stiffness contributes to develop hypertension (HT) and may be determined by an unbalance between the main extracellular proteins, like collagen and elastin. Previous studies have demonstrated that dexamethasone (DEX) increases arterial pressure (AP) in rats and humans; however the DEX effects on arterial stiffness are unclear. On the other hand, combined physical training (CT) has been recommended to control hypertension, but almost nothing is known about its effects on mechanisms responsible to control arterial stiffness. We hypothesized that CT could control collagen and elastin levels and attenuate arterial stiffness and AP increase in DEX-treated rats. Therefore, the aim of this study was to evaluate the effects of CT on arterial stiffness and AP in DEX-treated rats. Thirty-seven Wistar rats (200-250g) were allocated into 4 groups: sedentary control (SC, n = 8), sedentary treated with DEX (SD, n = 9), trained control (TC, n=10) and trained and treated with DEX (TD, n = 10). All rats performed a maximum voluntary carrying capacity test (MVCC, on the ladder) and a maximal physical capacity test (TEM, on the treadmill) and underwent CT (60% maximum, 5d / week, 1h / on alternate days, for 74 days) or were kept sedentary. Through the last 14 days, they were treated with DEX (50μg / kg per day, s.c.) or saline. At the end experimental protocol, rats underwent pulse wave velocity (PWV) and tail AP measurements. Two-way ANOVA and T-Student t-test were used to compare the groups. Tukey post-hoc test was used when necessary. Maximal physical capacity test or MVCC values, PWV and AP were correlated by Pearson/Spearman test (p