Changes in antioxidative mechanisms in elderly patients with non-insulin-dependent diabetes mellitus. Investigation of the redox dynamics of alpha-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.


CONCLUSIONS
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.
Yanagawa
K
K
Department of Geriatrics, Tokyo Medical University, Tokyo, Japan.
Takeda
H
H
Egashira
T
T
Matsumiya
T
T
Shibuya
T
T
Takasaki
M
M
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D000975:Antioxidants / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D004910:Erythrocyte Membrane / Q000737:chemistry*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D011336:Probability; D012016:Reference Values; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D014810:Vitamin E / Q000097:blood*
D000975:Antioxidants; D014810:Vitamin E