In this study we investigated the effects of ageing on the carbonyl stress (protein carbonyls and 4‐hydroxy‐2‐nonenal groups) and glutathione antioxidant defense in red blood cells (RBCs) of obese Type 2 diabetic patients with/without hypertensive complications. To this purpose the following methods were used: spectrophotometry (protein carbonyls, glutathione and glutathione peroxidase assays), immunofluorescence (4‐hydroxy‐2‐nonenal localization), western blotting (immunodetection of carbonylated proteins). The results showed that compared to RBCs of healthy subjects, in obese Type 2 diabetics, ageing is associated with: (i) an increase in the concentration and expression of carbonylated proteins, a marker of oxidative stress; (ii) a decrease of both non‐enzymatic and enzymatic endogenous glutathione defenses; (iii) a severely disturbed oxidant/antioxidant balance when obesity was associated with hypertension. The simultaneous insults of high blood pressure, obesity, and diabetes conducted to the highest carbonyl strss, exposure of 4‐hydroxy‐2‐nonenal Michel adducts at the outer leaflet of RBCs plasmalemma, and the lowest glutathione antioxidant potential, particularly in elderly patients. These results can explain the gradual age‐dependent diminishment of the detoxification potenital of RBCs that at the old age can not overcome the deleterious effects of the high systemic oxidative stress.
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