Effects of L-carnitine on RBC membrane composition and function in hyperinsulinemic rats

The purpose of the study was to investigate the effects of L-carnitine (CA) on the susceptibility of erythrocyte (RBC) to peroxide-induced lipid oxidation, RBC membrane composition, ATPases activity and oxidative stress in fructose-fed hyperinsulinemic rats. The rats were subjected to experimental hyperinsulinemia and hyperglycemia by feeding a high fructose diet (60 g/100 g) for 6 weeks. The rats showed significant alterations in the RBC membrane composition. The protein content was lower than control animals, while cholesterol, phospholipids and free fatty acids were higher in fructose-fed animals. Significant differences in the total carbohydrate and relative proportions of hexose, hexosamine, sialic acid and fucose of membranes were observed. In these rats, membrane-bound ATPases (total ATPase, Na+, K+ ATPase, Mg2+ and Ca2+ ATPases) were significantly lower while thiobarbituric acid reactive substances (TBARS) and lipid hydroperoxides (LHP) in RBC membrane were significantly higher than those of control rats. The red cells were more susceptible to peroxide-induced oxidative stress that correlated with reduced levels of vitamin E found RBC membrane. When fructose-diet fed rats were treated simultaneously with CA (300 mg/kg b.w/day, i.p.), such alterations in membrane composition and enzyme activities did not occur. Effects of fructose loading on lipid peroxidation was also alleviated by CA. These findings suggest that high levels of dietary fructose is detrimental to RBC membrane integrity and that CA may have membrane stabilizing effects in this diet-induced model of type 2-diabetes.