Saudi Journal of Gastroenterology
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Year : 1996  |  Volume : 2  |  Issue : 1  |  Page : 19-28

Role of oxygen-derived free radicals on gastric mucosal injury induced by ischemia-reperfusion

1 Department of Pharmacology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
2 Department of Medicine, College of Medicine, King Saud University, Riyadh, Saudi Arabia
3 Department of Surgery, College of Medicine, King Saud University, Riyadh, Saudi Arabia
4 Department of Physiology, College of Medicine, King Saud University, Riyadh, Saudi Arabia

Correspondence Address:
Physiology Department, College of Medicine, King Saud University, P.O. Box 2925, Riyadh 11461
Saudi Arabia
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Source of Support: None, Conflict of Interest: None

PMID: 19864838

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A free radical is an unstable and highly-reactive chemical species capable of independent existence that contained one or more unpaired electrons in its outer orbital. A number of oxygen-derived free radicals (ODFRs) have been identified. However, superoxide (O-2) and hydroxyl (OH*) radicals are extensively studied. The univalent reduc­tion of oxygen to water produces a number of highly-reactive chemical intermediates such as O-2 and OH*, which are commonly-known as oxygen-derived free radicals. ODFRS may be formed from several sources as follows: a) mitochondrial cytochrome oxidase, b) xanthine oxidase, c) neutrophils and d) transitional metals. There are several important defense mechanisms to limit or to prevent the damage caused by excessive ODFRs activity. These antioxidant defenses can be divided into a) enzymatic defense mechanisms such as : superoxide dismutase (SOD): catalase: selenium-containing glutathione peroxidase and b) non-enzymatic defense mechanisms including: alpha­tocopherol; ascorbic acid; glutathione and any sulfhydryl-containing compounds.

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