HIGH PEROXIDATIVE SUSCEPTIBILITY OF FISH-OIL POLYUNSATURATED FATTY-ACID IN CULTURED RAT HEPATOCYTES

The peroxidative susceptibility in cultured rat hepatocytes of eicosap entaenoic acid (EPA) and other polyunsaturated fatty acids (PUFA) with different numbers of double bonds was examined. Lipid peroxidation wa s evaluated using a newly developed HPLC procedure which includes the determination of malondialdehyde (MDA). Following exposure to 0.25-1.0 mM EPA adsorbed to BSA (EPA-BSA), cultured hepatocytes produced MDA i n the fatty acid concentration- and incubation time-dependent manner. The rate of MDA production by hepatocytes varied greatly with the degr ee of PUFA unsaturation, and ranked as follows: docosahexaenoic acid > EPA > arachidonic acid > alpha-linolenic acid = gamma-linolenic acid > linoleic acid > oleic acid. Prolonged exposure of cultured hepatocyt es to 1.0 mM EPA-BSA resulted in substantial leakage of LDH into the m edium. The cell injury was associated with the loss of cellular GSH an d protein thiol groups. Cotreatment of the EPA-supplemented hepatocyte s with a GSH-depleting agent, diethylmaleate, promoted the cellular pr otein thiol loss and LDH leakage. An iron chelator, deferoxamine, and other antioxidants such as N,N-diphenyl-p-phenylenediamine and gamma-t ocopherol efficiently prevented MDA production and consequently LDH le akage in the EPA-supplemented hepatocytes. These results show that per oxidative deterioration in excess of GSH-dependent defense mechanisms may occur in hepatocytes loaded with highly peroxidizable fish oil PUF A. (C) 1994 Academic Press, Inc.