Plasma Membrane Redox System in the Erythrocytes of Rowers: Pilot Study

Dear Editor-in-ChiefThe oxidative stress results from a change in the physiological balance between oxidant and anti-oxidant species. This type of stress is a chemical change in the redox state of cells.The increased production of reactive species is related to an excessive metabolic activation, for example, from an intense physical exercise or an excessive caloric intake (1). In physiological con-ditions, muscle fibers are provided with an anti-oxidant system able to keep under control the ex-cessive production of Reactive Oxygen Species (ROS).Endogenous and exogenous antioxidants are in-volved in countering the damage caused by reac-tive chemical species on muscle skeletal system. High-intensity training is associated with in-creased oxidative stress, because of the muscular effort required and the activation of all the meta-bolic pathways for ATP synthesis. Rowing is very demanding of high power maintained over time, mostly produced from aerobic metabolism (2).The aim of this study was to evaluate the reduc-ing activity in plasma and in erythrocytes in a group of rowers compared to a group of sedenta-ry subjects, and then to evaluate the efficiency of the trans-plasma membrane electron transport (TPMET), also known as PMRS, in the erythro-cytes of rowers as a compensatory mechanism of cellular redox homeostasis. Twenty-six healthy volunteers who did not practice physical activity at a competitive level (control subjects group) (26.6±2.2 yr) and twenty-two professional rowers were recruited (18.6±3.1 yr). Venous blood sam-ples were collected from rowers and control group after overnight fast. After centrifugation at 3000 rpm for 10 min at 4 °C, plasma was separated from red blood cells. The resultant plasma was transferred to micro centrifuge tubes and used at least in part for ferric-reducing activi-ty power (FRAP) assay. Red blood cells, after removal of buffy coat and upper 15% of the packed red blood cells, were washed two times with cold PBS (3). The ferric reducing activity in plasma and erythrocytes (FRAP) assay was per-formed (4). The PMRS activity was evaluated by reduction of 1 mM-ferricyanide (FIC) solution in PBS (pH 7.4) in ferrocyanide (FOC), using 1, 10-phenanthroline as an indicator and measuring ab-sorption at 510 nm. All analyses were performed using GraphPad Prism 5 (GraphPad Software Inc., Chicago, IL, USA). The statistical signific-ance level was set at PThe main finding of this study concern the activi-ty of plasma membrane redox system (PMRS): it has been elevated of 35% in RBCs from rowers than in RBCs from untrained group. The PMRS operated to maintain the ascorbate level in plas-ma, concerning the compensatory/protective mechanism. …