The role of lipid peroxidation in the chemical-dependent activation of hepatic phospholipase C in vitro.

This study assessed the role of lipid peroxidation in the chemical-dependent activation of hepatic phospholipase C in vitro. Hepatocellular membranes (1000 X g) were incubated with sn-[1,3-14C] glycerol-3-P, ATP, CoA, palmitate, Ca2+, NaF and dithiothreitol to form membrane-bound, labeled phosphatidic acid. Membrane-associated phosphatidate was incubated (10-45 min) with 2 mM Fe2+SO4 or 5mM CCl4 in the presence or absence of various antioxidants. Membranes exposed to Fe2+SO4 displayed an antioxidant-sensitive, 20-fold increase in malonic dialdehyde (MDA) formation without measurable increase in phospholipase C activity. In contrast, membranes exposed to 5 mM CCl4 displayed an antioxidant-insensitive, 2-3-fold increase in phospholipase C activity without significant increase in MDA production. These results suggest that under these incubation conditions in vitro, the CCl4-dependent activation of hepatic phospholipase C is not regulated by nor dependent upon the peroxidation of membrane phospholipids.