Recently, myoglobin has been implicated as a free radical generator that results in lipoperoxidation during ischemia-reperfusion injury of myocardium . The generation of free radicals is one damaging effect of hypoxia . Normally, oxygen free radicals are maintained at low levels by endogenous antioxidant systems (mainly SOD, CAT, etc). SOD especially scavenges superoxide free radicals, and CAT scavenges peroxide. SOD and CAT prevent activation of the lipid peroxidation chain reaction. Extensive lipid peroxidation results in a variety of degradation products, one of which is MDA. As shown in Table 2, an increase in SOD activity was accompanied by a decrease in MDA content in the left myocardium after intermittent hypoxia (3500 m, 6 h daily for six weeks). The results indicate that the increase in antioxidant enzyme activity makes the myocardium more resistant to hypoxia by suppressing lipoperoxidation.Because a stress reaction is evoked by the most diverse external factors acting on the organism, the stress-limiting systems are also activated naturally. Intermittent hypoxia arouses and mobilizes organic self protection. However, the mechanism by which this occurs is not clear. Adaptation to intermittent hypoxia is accompanied by an increase in antioxidant enzymes. Meerson postulated that the protective effects of intermittent hypoxia on myocardium were related mainly to the antioxidant system. In his opinion, increased tolerance to hypoxia, induced by intermittent hypoxia, occurs through increasing antioxidant enzyme activity. Our studies showed that SOD and CAT activity increased only after six weeks of intermittent hypoxia. Changes in SOD and CAT activity were different in the left and right myocardium. You can finally enjoy safe online shopping for Symbicort Dosage with the pharmacy you can fully trust no matter if you need a small amount of this medicine or would like to purchase it in bulk not to have to think about it for a long time.