Are ethane and pentane evolution and thiobarbituric acid reactivity specific for lipid peroxidation in erythrocyte membranes?

Abstract

Peroxidation of human erythrocyte membranes was followed in vitro with head space analysis of ethane and pentane and a thiobarbituric acid assay in a standardized system liberating free oxygen radicals. Simultaneously, the decrease of the membrane palmitic, linoleic, arachidonic and docosahexaenoic acid was monitored. The recoveries of the peroxidation products of the red cell ghost preparations were compared with those obtained by peroxidation of pure fatty acids.

Experiments using purified fatty acids revealed that ethane was preferentially produced from docosahexaenoic and linolenic, and pentane from linoleic and arachidonic acids. Thiobarbituric acid-reactive material (TBAR) was produced from each unsaturated fatty acid tested, but the amount was dependent on the number of carbon chain double bonds.

During peroxidation of the erythrocyte ghosts, 72% of ethane and 51% pentane were produced during the first 12 h of incubation, whereas TBAR was produced at a constant rate throughout the 36-h test period. Hydrocarbon and TBAR production were similarly inhibited by desferoxamine (at p < 0.005 and p < 0.0001, respectively). The total recoveries of ethane, pentane and TBAR exceeded the amount expected by 7.8-, 1.4-and 5.5-fold, respectively. It was concluded that measurement of pentane is a reliable method to monitor lipid peroxidation during oxidative damage of the erythrocyte membrane.

Key Words:

• free oxygen radicals
• malondialdehyde
• membrane damage
• volatile hydrocarbons