Analysis of the toxic effects of linoleic acid, 12,13-cis-epoxyoctadecenoic acid, and 12,13-dihydroxyoctadecenoic acid in rabbit renal cortical mitochondria

P450 epoxidation of linoleic acid has been associated with many pathologica l conditions that often lead to acute renal failure. However, there is only suggestive evidence that linoleic acid monoepoxides and/or linoleic diols directly induce mitochondrial dysfunction. Using isolated rabbit renal cort ical mitochondria (RCM), we found that linoleic acid (50 muM) and the linol eic acid monoepoxide, cis-12, 13-epoxy-9-octadecenoic acid (12,13-EOA, 50 m uM) increased state 4 and oligomycin-insensitive respiration and reduced st ate 3 and oligomycin-sensitive respiration. Concomitant with these effects, linoleic acid and 12,13-EOA decreased mitochondrial membrane potential (De lta Psi). In contrast, the hydrolyzed product of 12,13-EOA, 12,13-dihydroxy octadecenoic acid (12,13-DHOA, 50 muM), had no effect on state 3, state 4, oligomycin-sensitive, and oligomycin-insensitive respiration, and Delta Psi . Neither linoleic acid or its metabolites altered uncoupled respiration, w hich suggests that these compounds have no affect on electron transport cha in in RCM. Nucleotides such as ATP (0.5 mM) and GDP (0.5 mM) partially prev ented the decrease in Delta Psi but did not attenuate the increase in oligo mycin-insensitive respiration after exposure to linoleic acid (50 muM) and 12,13-EOA (50 muM). These results demonstrate that linoleic acid metabolism to the 12,13-DHOA is a detoxification pathway that prevents mitochondrial dysfunction in RCM. The increase in state 4 respiration concomitant with de creases in state 3 respiration and Delta Psi suggest that, in addition to u ncoupling effects, linoleic acid and 12,13-EOA may have other effects, such as alterations of mitochondrial membranes. The inability of ATP and GDP to fully attenuate the uncoupling effects of linoleic acid and 12,13-EOA sugg ests that these effects are mediated through a nucleotide-independent mecha nism. (C) 2001 Academic Press.