Erythrocyte membrane fluidity and tissue lipid peroxides in female guinea-pigs on graded vitamin C intake.

The effect of low (1 mg/animal/day), medium (10 mg/animal/day) and high (100 mg/animal/day) intake of ascorbic acid on tissue lipid peroxidation (LPO) and the physical state of erythrocyte membranes was investigated in female guinea-pigs fed a vitamin E low diet. Animals were killed after 9-11 weeks and the blood, liver, lungs, kidneys and adrenals were analysed. The LPO was estimated by the determination of malondialdehyde with HPLC. The physical state of erythrocyte membranes was determined spectrofluorometrically and expressed as fluorescence polarization of membrane lipid specific probe 1,6-diphenyl-1,3,5-hexatriene. The LPO concentrations in the liver and adrenals of the group on a low vitamin C intake were significantly increased. A significant non-linear negative correlation between C vitamin levels and LPO concentrations was found in these tissues. The fluidity of erythrocyte membranes as a measure of their structural state was significantly lower in the group with a low intake of C vitamin. It is probable that the water-soluble antioxidants, such as vitamin C, act in the plasma as primary defense against oxidative stress if the radicals are formed initially in the aqueous phase of whole blood.