Ascorbate recycling by erythrocytes during aging in humans.

Erythrocytes play a crucial role in recycling ascorbate in blood plasma. The erythrocyte ascorbate free radical (AFR) reductase is involved in the reduction of AFR to ascorbic acid (ASC) in the plasma. In the present study, we report an age-dependent increase in the activity of erythrocyte AFR reductase in humans that shows a significant positive correlation with the activity of plasma membrane redox system (PMRS). We explain the age-dependent increase in erythrocyte ASC recycling on the basis of a compensatory/protective mechanism that operates to maintain the ASC level in plasma and thereby minimize oxidative stress during aging.