Aerobic training workload affects human endothelial cells redox homeostasis.

PURPOSE: Moderate aerobic exercise reduces oxidative stress, whereas intense physical activity may produce the opposite result. At present, the effects of different exercise loads on oxidative stress markers and the response of human cells to different exercise volumes have not been fully elucidated. METHODS: Human (Eahy-926) endothelial cells (EC), exposed or not exposed to oxidative stress, were conditioned with sera from two groups of triathletes practicing at different workloads. RESULTS: Although no differences in functional and hemodynamic variables were observed between the two groups of triathletes, significant changes in some markers for oxidative stress were found in their sera. Thiobarbituric acid reactive substances and superoxide dismutase activity were similar, but triathletes practicing the sport at lower volume (T1) had higher serum nitric oxide and lower catalase activity than triathletes performing the training at greater load (T2). The EC conditioned with serum from T1 (T1-EC) showed higher survival and proliferation rates and lower senescence levels than the EC supplemented with T2 (T2-EC) serum both before and after oxidative stress induction. These effects depended on catalase as demonstrated via enzyme activity inhibition using 3-amino-1,2,4-triazole. After oxidative stress induction, Sirt1 activity, a regulator of the oxidative stress response, was significantly increased in the T1-EC but not in the T2-EC. Moreover, the T1-EC required less catalase activity than the T2-EC to counteract an equal amount of oxidative stress after H2O2 administration. CONCLUSION: This study demonstrates that the beneficial effects of aerobic exercise are eliminated when the training is performed at a greater workload. Moreover, we suggest an oxidative stress marker, serum catalase activity, as a valid tool to use in the supervision of changes to exercise volume.

Oxidative stress effects on endothelial cells treated with different athletes' sera.

PURPOSE: Exercise training is a nonpharmacological intervention that improves cardiovascular function and enhances endothelial homeostasis in patients with cardiovascular diseases. However, the amount of benefit achieved varies widely depending on the type and duration of exercise. Moreover, data about the long-term effects of physical activity are scarce. METHODS: In this study, endothelial cells, exposed or not to oxidative stress, were conditioned with sera from athletes regularly participating in sports classified as "aerobic" (triathlon), "mixed aerobic-anaerobic" (soccer), and "anaerobic" (sprint running). RESULTS: Functional and hemodynamic variables did not differ between groups of athletes, whereas there were dramatic changes in serum markers for oxidative stress. Lipid peroxidation assessed by the thiobarbituric acid reactive substances assay and catalase activity were the lowest and nitric oxide availability was the highest in sera of triathletes. Endothelial cells cultured in serum from triathletes (T-endothelial cells) had the highest survival, evaluated by viability assay, BrdU incorporation, and senescence-associated ß galactosidase assays, and preserved the endothelial appearance before and after stress in contrast to the cells grown in sera from the other athletes. T-endothelial cells also had the highest catalase messenger RNA expression and, after stress, the highest catalase activity of all the endothelial cells. Moreover, poststress activity of Sirt1, a NAD(+)-dependent deacetylase involved in cellular stress resistance and a key regulator of longevity, was significantly increased in T-endothelial cells. CONCLUSIONS: Different types of exercise training induced different molecular effects in terms of survival, morphology, and antioxidant system efficiency. The in vitro technique used herein may help to shed light on the molecular basis of effects of long-term physical activity in humans.