Ascorbate uptake and antioxidant function in peritoneal macrophages
- 作者：James M. May ; Liying Li ; Zhi-chao Qu and Junjun Huang
- 关键词：Ascorbate transport ; Dehydroascorbic acid ; Oxidant stress ; Phagocytosis ; α ; -Tocopherol ; Mouse peritoneal macrophages ; SVCT2 ; Glutathione ; Phagocytosis ; Dihydrofluorescein
- 刊名：Archives of Biochemistry and Biophysics
- 出版年：2005
- 期刊代码：116_00039861
- 类别：ch
- 出版时间：2005
- 卷：440
- 期：2
- 页码：165-172
- 文件大小：407 K
摘要
Since activated macrophages generate potentially deleterious reactive oxygen species, we studied whether ascorbic acid might function as an antioxidant in these cells. Thioglycollate-elicited murine peritoneal macrophages contained about 3 mM ascorbate that was halved by culture in ascorbate-free medium. However, the cells took up added ascorbate to concentrations of 6–8 mM by a high-affinity sodium-dependent transport mechanism. This likely reflected the activity of the SVCT2 ascorbate transporter, since its message and protein were present in the cells. Activation of the cells by phagocytosis of latex particles depleted intracellular ascorbate, although not below the basal levels present in the cells in culture. Glutathione (GSH) was unaffected by phagocytosis, suggesting that ascorbate was more sensitive to the oxidant stress of phagocytosis than GSH. Phagocytosis induced a modest increase in reactive oxygen species as well as a progressive loss of α-tocopherol, both of which were prevented in cells loaded with ascorbate. These results suggest that activated macrophages can use ascorbate to lessen self-generated oxidant stress and spare α-tocopherol, which may protect these long-lived cells from necrosis or apoptosis.