The Ros Scavenger Pdtc Affects Adaptation To Treadmill Running In Mice: Distinct Effects On Murine Body Mass, Resting Heart Rate And Skeletal Muscle Fiber Type Composition

Regular exercise induces a broad spectrum of adaptation reactions in a variety of tissues and organs. However, the respective mechanisms are incompletely understood. In the context of their analysis, animal model systems, specifically rodent treadmill running protocols, playan important role. However, few researchers have studied different aspects of adaptation, such as cardiorespiratory and skeletal muscle training effects, within one set of experiments. Here, we analyzed physiological adaptation to 10 weeks of regular, moderate-intensity, uphill treadmill running inmice, awidely usedmodel for endurance exercise training. To study the effects of reactive oxygen species (ROS), which have been suggested to be major regulators of training adaptation, a subgroup of mice was treated with the ROS scavenger PDTC (pyrrolidine dithiocarbamate). We found that mass gain in mice that exercised under PDTC treatment lagged behind that of all other experimental groups. In addition, both exercise and PDTC significantly and additively decreased resting heart rate. Furthermore, there was a trend towards an enhanced proportion of type 2A skeletal muscle fibers and differential expression of metabolism-associated genes, indicating metabolic and functional adaptation of skeletalmuscle fibers. By contrast, therewere no effects on grip strength and relative mass of individual muscles, suggesting that our protocol of uphill running did not increase skeletal muscle hypertrophyandstrength. Takentogether, ourdatasuggest thata standard protocolofmoderate-intensityuphill running induces adaptation reactions atmultiple levels, part ofwhich might bemodulated by ROS, but does not enhance skeletal muscle hypertrophy and force.