Relation between free fatty acid and acyl-CoA concentrations in rat brain following decapitation.

To ascertain effects of total ischemia on brain phospholipid metabolism, anesthetized rats were decapitated and unesterified fatty acids and long chain acyl-CoA concentrations were analyzed in brain after 3 or 15 min. Control brain was taken from rats that were microwaved. Fatty acids were quantitated by extraction, thin layer chromatography and gas chromatography. Long-chain acyl-CoAs were quantitated by solubilization, solid phase extraction with an oligonucleotide purification cartridge and HPLC. Unesterified fatty acid concentrations increased significantly after decapitation, most dramatically for arachidonic acid (76 fold at 15 min) followed by docosahexaenoic acid. Of the acyl-CoA molecular species only the concentration of arachidonoyl-CoA was increased at 3 min and 15 min after decapitation, by 3-4 fold compared with microwaved brain. The concentration of docosahexaenoyl-CoA fell whereas concentrations of the other acyl-CoAs were unchanged. The increase in arachidonoyl-CoA after decapitation indicates that reincorporation of arachidonic acid into membrane phospholipids is possible during ischemia, likely at the expense of docosahexaenoic acid.