Influence of diet on lipid oxidation and membrane structure in porcine muscle microsomes

The effect of oxidized dietary lipid (corn oil) and dietary vitamin E (alpha-tocopherol) on the fluidity of porcine muscle microsomal membranes was investigated. Using the membrane probe diphenylhexatriene, fluorescence anisotropy measurements showed that microsomal membrane fluidity decreased during FeCl2-induced lipid peroxidation. Microsomes from pigs fed an alpha-tocopherol-supplemented diet (200 mg of alpha-tocopheryl acetate/kg of diet) were significantly less susceptible (P 0.05) to FeCl2-induced lipid peroxidation and to changes in membrane fluidity compared to muscle microsomes from pigs fed a basal diet (10 mg/kg of diet). Compared to unoxidized dietary corn oil, consumption of oxidized oil (4.5 mequiv of peroxide/kg of diet) did not significantly affect the rate of peroxidation of the microsomal lipids but led to a significant decrease in membrane fluidity. Results suggested that the reduced exudation in pork steaks from pigs fed supplemental alpha-tocopherol, observed in this study and in an earlier study, did not appear to be directly related to oxidation-induced changes in membrane fluidity. However, further studies are needed to more adequately evaluate this observation