Effect of Ca(2+) Channel Blockers, External Ca(2+) and Phospholipase A(2) Inhibitors on t-butylhydroperoxide-induced Lipid Peroxidation and Toxicity in Rat Liver Slices

OBJECTIVES: This study was undertaken to examine the effect of oxidant on lipid peroxidation and lethal cell injury in rat liver slices. METHODS: t-Butylhydroperoxide (t-BHP) was employed as a model of an oxidant. The lipid peroxidation and lethal cell injury were estimated by measuring the formation of malondialdehyde (MDA) and lactate dehydrogenase (LDH) release, respectively. RESULTS: t-BHP increased lipid peroxidation and LDH release in a dose-dependent manner over concentrations of 0.5–10mM. t-BHP-induced lipid peroxidation was completely prevented by an antioxidant, N,N-diphenyl-p-phenylenediamine (DPPD), but LDH release was partially decreased. Both t-BHP-induced lipid peroxidation and LDH release were significantly protected by iron chelator, deferoxamine, sulfhydryl reducing agent, dithiothreitol and glutathione. Ca(2+) channel blockers, verapamil, diltiazem and nifedipine exerted a significant protective effect against t-BHP-induced lipid peroxidation and LDH release. By contrast, addition of external Ca(2+) chelator, ethylene glycol bis(b-aminoethyl ether)-N,N-tetraacetic acid (EGTA) did not alter t-BHP-induced lipid peroxidation, whereas t-BHP-induced lethal cell injury was significantly prevented. Phospholipase A(2) (PLA(2)) inhibitors, mepacrine and butacaine produced a partial protective effect. CONCLUSIONS: These results suggest that t-BHP induces cell injury by lipid peroxidation-dependent and -independent mechanisms which can be partially prevented by Ca(2+) channel blockers and PLA(2) inhibitors.