Red blood cell glucose-6-phosphate dehydrogenase activity in aged humans.

The enzyme glucose-6-phosphate dehydrogenase (G6PD) was assayed in the circulating erythrocytes of 38 20-to 30-year-old subjects and 29 80- to 90-year-old subjects. The red blood cell G6PD activity of an aged-unbiased erythrocyte population in the young group was found to be significantly higher than in the older group (5.46 +/- 1.06) vs (4.31 +/- 0.99) (P less than 0.001), respectively (mean +/- SD). No significant difference was observed between the mean enzyme values of the male and female subjects in the two age groups. Since the mature red blood cell is devoid of regenerative capabilities, one may propose an explanation for this observation that implicates either an alteration in G6PD synthesis in the erythrocyte precursor cells in aged hosts, and/or the presence of an inhibitory factor that has the effect of decreasing the assayed activity for this enzyme.