Molecular Pathways Involved in Aerobic Exercise Training Enhance Vascular Relaxation
Suliana Mesquita Paula, Tiago Lazzaretti Fernandes, Gisele Kruger Couto, Maria Tereza Jordão, Edilamar Menezes de Oliveira, Lisete Compagno Michelini, Luciana Venturini Rossoni
Abstract
PURPOSE: The beneficial effects of exercise training on the cardiovascular system are well known. Because our knowledge of exercise-induced vascular function is still limited, we aimed to uncover the molecular mechanisms conditioning the improved vascular relaxation in muscular arteries. METHODS: Male Wistar-Kyoto rats with the same ability to run on a treadmill after maximal exercise tests were allocated to the following two groups: trained (Tr) (treadmill, 50%-60% of maximal capacity, 5 d·wk) and untrained (UnTr). After 13 wk, the femoral arteries were harvested and used for functional, structural, and molecular analyses. RESULTS: Acetylcholine (ACh)-induced relaxation and nitric oxide (NO) production were enhanced in arteries from Tr rats compared with UnTr rats. Tr arteries exhibited reduced microRNA (miRNA)-124a expression (whose target is caveolin-1), increased the density of caveolae aligned along the sarcolemma and reduced ACh-induced relaxation in the presence of methyl-β-cyclodextrin, which disrupts caveolae. Higher endothelial NO synthase (eNOS) expression with lower miRNA-155 expression and the posttranslational modification of eNOS (phosphorylation of stimulatory Ser1177 and dephosphorylation of inhibitory Thr495) by the PI3-kinase/Akt1/2/3 pathway also contributed to the higher NO production induced by exercise training. Furthermore, increased Cu/Zn- and extracellular-superoxide dismutase expression and enhanced effects of their pharmacological scavenger activity on the ACh-induced response were observed in Tr arteries. CONCLUSIONS: The results of the present study provide a molecular basis for exercise-induced NO bioavailability in healthy femoral arteries. Increased caveolae domain and eNOS expression/activity in Tr arteries are associated with downregulation of miRNA-124a and -155, as well as are involved with higher antioxidant defense, subsequently inducing a favorable endothelium-dependent milieu in Tr arteries.