Lipid peroxidation in rat tissue slices: Effect of dietary vitamin E, corn oil-lard and menhaden oil

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Abstract
Rats were fed for 5 weeks either 10% (w/w) menhaden oil (MO) or a 10% corn oil-lard (COL) mixture (1∶1) in diets with ≤5 IU or ≤2 IU/kg vitamin E, respectively, or the same diets supplemented with d-α-tocopheryl succinate to a total of 35 and 180 IU vitamin E/kg, respectively. Slices of liver and heart from these rats were used to study lipid peroxidationin vitro. Thiobarbituric acid-reactive substances (TBARS) were measured in the medium after incubation of the slices at 37°C for 1 hr in the absence (uninduced) and presence of 0.5 mM tert-butyl hydroperoxide (induced). The release of TBARS from slices of heart and liver from rats fed either lipid decreased with increasing levels of dietary vitamin E. At the same level of dietary vitamin E, TBARS release was greater for slices of liver and heart from the MO-fed rats than from the COL-fed rats. Application of the TBARS data to a model simulating the experimental conditions showed a good correlation (r=0.95, pin vitro lipid peroxidation, and that vitamin E decreased TBARS in tissues from rats fed COL to lower levels than for tissues from rats fed MO. The results suggest that there might also be an increased requirement for dietary antioxidants by humans using fish oil supplements.