Changes in antioxidative mechanisms in elderly patients with non-insulin-dependent diabetes mellitus -: Investigation of the redox dynamics of α-tocopherol in erythrocyte membranes

Background: Recently, it has been suggested that the onset and aggravation of diabetes are closely related to free radicals. Also, vitamin E is a lipophilic free radical scavenger that is localized mainly in biomembranes. Objective: The purpose of this study was to clarify the defensive mechanisms against oxidative stress by investigating the differences in the redox dynamics of alpha -tocopherol in plasma and erythrocyte membranes between elderly patients with non-insulin-dependent diabetes mellitus (NIDDM) and healthy elderly subjects. Methods: Total, alpha-, beta-, gamma- and delta -tocopherol and alpha -tocopherolquinone concentrations were determined by high-performance liquid chromatography with a redox detection mode using a series of four coulometric working electrodes. Results: The alpha -tocopherolquinone/alpha -tocopherol ratio in plasma and erythrocyte membranes was not different between the two groups. Both the alpha -tocopherol concentrations in erythrocyte membranes and ratio of alpha -tocopherol in erythrocyte membranes to alpha -tocopherol in plasma was significantly lower in elderly NIDDM patients than in healthy subjects. Conclusion: These findings suggest that alpha -tocopherol is used normally in both plasma and erythrocyte membranes and alpha -tocopherol uptake in erythrocyte membranes is significantly decreased in elderly NIDDM patients. The functional disorder of the antioxidative activity of alpha -tocopherol in erythrocyte membranes due to impairment of this transfer mechanism may be associated with the pathogenesis of NIDDM, Copyright (C) 2001 S. Karger AG, Basel.