Vitamin C Research Today is a free monthly online journal that collates and summarizes the latest research about Vitamin C, including details on benefits, dosage, supplements, information.

Ascorbate uptake and antioxidant function in peritoneal macrophages.

May JM, Li L, Qu ZC, Huang J

Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232-6303, USA. james.may@vanderbilt.edu

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 alpha-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 alpha-tocopherol, which may protect these long-lived cells from necrosis or apoptosis.

Published 15 August 2005 in Arch Biochem Biophys, 440(2): 165-72.
Full-text of this article is available online (may require subscription).

© 2004-2008 Vitamin C Research Today. All Rights Reserved.