Effect of storage time on Trx reductase system in RBC. Thioredoxin reductase activity (A), thioredoxin levels (B), and NADPH levels (C) were measured in RBCs stored for 7 or 35 days as described in Materials and Methods section. Data are mean±SEM [n=8–9 for (A), and n=3 for (B, C)]. In all cases, differences were not significant by unpaired t-test. Trx, thioredoxin.