Effect And Mechanism Of Exhaustive Exercise Induced Oxidative Stress In Erythrocytes Of Rat

It is widely accepted that regular exercise reduces morbidity and mortality relatedto vascular diseases. The hypothesis about the mechanisms of this protective effect ismostly based on the metabolic alterations that affect cardiovascular risk factors.Alternatively, exercise-related sudden death is also a well-documented phenomenon andis accepted to have a cardiovascular origin in most cases. During the past three decades,our knowledge about the biological implications of exercise-induced oxidative stresshas expanded. Several studies have suggested that ventricular fibrillation is the mostcommon cause of exercise induced sudden death; however, the exact mechanismsleading to this fatal arrhythmia are not clear. In many cases, an existing coronarydisease process is found, but total occlusion of the coronaries is not a frequent finding.Inadequate blood supply to the myocardium as a result of atherosclerotic narrowing orthrombus generation, in addition to exercise-induced coronary artery spasm, has beendiscussed as the underlying cause of myocardial ischemia leading to fatal arrhythmias.A frequently ignored factor that affects blood flow is its fluidity, and this property ofblood might be altered dramatically during and/or after exercise. Therefore, the studyinvolve to oxidative damage, free radical scavenge, and antioxidant capacity and itsinfluence to mechanical properties and oxygen carrying capabilities of RBC duringdifferent exercise condition will provides us an important theoretical basis for exploringin a variety of exercise-induced physiological and pathological phenomena such asshock and hypoxic injury.Body will produce large amounts of reactive oxygen species (ROS) during exercise.Those ROS generated in the organization will release to the plasma quickly. AlthoughRBC has a excellent antioxidant mechanisms, enabled it to clear ROS attack from theintracellular and extracellular timely. But when the body continuously, under stress toproduce large amounts of ROS and released into the plasma, the redox equilibrium ofRBC will be broken. The antioxidant index of erythrocytes from control andexercise-exhausted groups were evaluated.The results show that: the activity oferythrocyte antioxidant enzymes SOD and CAT increased significantly after exhaustiveexercise, at the same time, the content of GSH declined significantly. RBC lipid TBARSlevels was detedted by TBA test, results show that, erythrocyte membrane lipid TBARSlevels were significantly elevated in rats after exhaustive exercise. Erythrocyte membrane protein is rich in free thiol, which plays an important role in maintain thenormal structure and function of enzymes and protein of RBC. Compared with thecontrol group, protein free thiol content of erythrocyte membranes was decreasedsignificantly after exhaustive exercise.Band3is the major integral protein of the RBC membrane, and it plays a crucialrole in membrane functional organization, stability and RBC volume regulation. Incontrast, changes in band-3structure and its membrane organization have been observedafter oxidative stress or during physiological aging of RBCs and are accompanied bycell shrinkage, decreased cell deformability and alterations in RBC metabolic activity.Thus, band-3is a potential molecular target in exercise-related blood disease, andalterations in band-3may be associated with RBC dysfunction during exerciseconditions. Our work clearly showed the formation of conjugated membrane proteins toform HMW protein complexes during exhaustive exercise. Furthermore, the significantdecrease of HMW bands along with decline in clustered EB3after incubation with DTTin ERE groups suggested that free superoxide radicals attack the free thiol groups of themembrane proteins, thereby inducing clustering among EB3in membrane proteinsthrough the formation of reducible inter-and/or intra molecular disulfide bonds. Underthese conditions, our findings suggest that oxidized/oligomeric EB3impairs withexhaustive exercise induced oxidative stress. Therefore, antioxidant therapy could beused to prevent RBCs from exhaustive exercise-induced haemorheologicalabnormalities by reducing the oxidative stress.In this report, we indeed found that the changes in oxygen tension conditionsRBCs are subject to different degrees of oxidative damage under the same oxidationmodel. Compared with hyperoxia and normoxic conditions erythrocytes are moresusceptible to free radical attack under hypoxic conditions. Besides, to reveal theunderlying mechanism we researched the changes in antioxidant capacity of RBCsunder gradient oxygen tension conditions and the relationship with the changes of RBCglucose metabolism. These experimental findings reflect an underlying molecularmechanism by which hypoxic exposure induces free radical oxidative damage invarious tissues.In summary, exhaustive exercise caused significant oxidative damage in rats,including membrane lipid peroxidation, membrane protein cross-linking andhemoglobin oxidation. Membrane protein oxidative damage, especially significantlyincreased Band3clustering and phosphorylation induced significantly decline of oxygen-carrying capacity and deformability of RBCs after exhaustive exercise. This isan underlying molecular mechanism by which inadequate supplies of blood and oxygento tissues leads to exercise-related diseases. In addition, in vitro experiments shown thatthe oxygen content of red blood cells is closely related to oxidative damage, when thered blood cells in a state of oxidative stress, decreased blood oxygen content wouldpromote oxidative damage in red blood cells.