Lipid peroxidation in electroporated hepatocytes occurs much more readily than does hydroxyl-radical formation.
1. Rat hepatocytes suspended in 0.25 M-sucrose were electropermeabilized. This completely disrupted their plasma-membrane permeability barrier. 2. The endoplasmic reticulum in electroporated hepatocytes appeared morphologically preserved and maintained its permeability barrier as evidenced by electron-microscopic examination and latency measurements on luminal reticular enzymes. 3. Upon aerobic incubation with an NADPH-generating system and iron/ADP, porated hepatocytes peroxidized their membrane lipids at rates similar to those of matched microsomal preparations. 4. When hepatocytes were incubated with iron/EDTA and azide, radical formation detectable with dimethyl sulphoxide (DMSO) was only 10-20% that shown by microsomes. Omitting azide abolished hepatocyte reactivity with DMSO completely. Effects of hydroxyl-radical (.OH) scavengers and of added catalase suggest that the radical detected by DMSO is .OH. 5. Cytosolic inhibitor(s) from hepatocytes seemed to be a major factor limiting .OH formation. These were macromolecular, but showed a degree of heat-stability. Dialysis largely abolished inhibition, but this could be restored again by adding GSH. 6. Since .OH formation in hepatocytes seems to be much more stringently prevented than lipid peroxidation, free-radical damage originating from intracellular redox systems seems more likely to take the form of lipid peroxidation.
Hallinan
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Department of Biochemistry, Royal Free Hospital School of Medicine, London, U.K.
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Rice-Evans
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Stanley
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O'Reilly
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Brown
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D000818:Animals; D002463:Cell Membrane Permeability; D003600:Cytosol / Q000378:metabolism; D004560:Electricity; D004721:Endoplasmic Reticulum / Q000201:enzymology; D005609:Free Radicals; D005952:Glucose-6-Phosphatase / Q000378:metabolism; D014453:Glucuronosyltransferase / Q000378:metabolism; D006878:Hydroxides / Q000737:chemistry* / Q000378:metabolism; D008054:Lipid Peroxides / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D005609:Free Radicals; D006878:Hydroxides; D008054:Lipid Peroxides; D014453:Glucuronosyltransferase; D005952:Glucose-6-Phosphatase