THE ROLE OF FREE-RADICALS IN COLD INJURIES

Cold injury is a tissue trauma produced by exposure to freezing temper atures and even brief exposure to a severely cold and windy environmen t. Rewarming of frozen tissue is associated with blood reperfusion and the simultaneous generation of free oxygen radicals. In this review i s discussed the current understanding of the mechanism of action of fr ee oxygen radicals as related to cold injury during rewarming. Decreas ed energy stores during ischaemia lead to the accumulation of adenine nucleotides and liberation of free fatty acids due to the breakdown of lipid membranes. On rewarming, free fatty acids are metabolized via c yclo-oxygenase and adenine nucleotides are metabolized via the xanthin e oxidase pathway. These may be the source of free oxygen radicals. Le ukocytes may also play a major role in the pathogenesis of cold injury . Oxygen radical scavengers, such as superoxide dismutase and catalase , may help to reduce the cold induced injury but their action is limit ed due to the inability readily to cross the plasma membrane. Lipid so luble antioxidants are likely to be more effective scavengers because of their presence in membranes where peroxidative reactions can be arr ested.