Housset B
Service de Pneumologie, Hôpital Saint-Antoine, Paris, France.
Bull Eur Physiopathol Respir. 1987 Jul-Aug;23(4):287-90.
The lung is particularly exposed to oxidant stresses, such as those that can be brought about by oxygen-derived free radicals. They mainly result from the monovalent reduction of molecular oxygen. The most reactive oxygen metabolite is the hydroxyl radical, whose formation appears to be dependent upon the presence of iron-chelates. Free radicals are normally produced by cellular metabolism. Furthermore, activated phagocytes, during the 'respiratory burst', release oxygen metabolites that are necessary for bacterial killing. Free radicals are highly reactive species. Their target molecules are proteins, DNA and polyunsaturated fatty acids whose alterations can lead to cell death. There are, however, several antioxidant substances which are enzymatic (superoxide dismutases, catalase and glutathione peroxidase) and non enzymatic (reduced glutathione, vitamin E and C etc...). In many experimental systems, an increase in antioxidant defences is associated with higher resistance to oxidant stress. However, the antioxidant system may be overwhelmed by an overproduction of intra and/or extracellular free radicals leading to tissue injury. Recent advances in the understanding of free radical metabolism can suggest some new therapeutic approaches such as the administration of exogenous antioxidant or iron chelators.
肺特别容易受到氧化应激的影响，比如那些由氧衍生的自由基所引发的氧化应激。它们主要源于分子氧的单价还原。最具活性的氧代谢产物是羟基自由基，其形成似乎依赖于铁螯合物的存在。自由基通常由细胞代谢产生。此外，被激活的吞噬细胞在“呼吸爆发”过程中会释放用于杀灭细菌的氧代谢产物。自由基是高活性物质。它们的靶分子是蛋白质、DNA和多不饱和脂肪酸，这些分子的改变会导致细胞死亡。然而，存在几种抗氧化物质，包括酶类（超氧化物歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶）和非酶类（还原型谷胱甘肽、维生素E和C等）。在许多实验系统中，抗氧化防御能力的增强与对氧化应激的更高抗性相关。然而，抗氧化系统可能会因细胞内和/或细胞外自由基的过度产生而不堪重负，从而导致组织损伤。对自由基代谢认识的最新进展可能会提示一些新的治疗方法，比如给予外源性抗氧化剂或铁螯合剂。
