RELATION BETWEEN FREE FATTY-ACID AND ACYL-COA CONCENTRATIONS IN RAT-BRAIN FOLLOWING DECAPITATION

To ascertain effects of total ischemia on brain phospholipid metabolis m, 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 ga s chromatography. Long-chain acyl-CoAs were quantitated by solubilizat ion, solid phase extraction with an oligonucleotide purification cartr idge and HPLC. Unesterified fatty acid concentrations increased signif icantly after decapitation, most dramatically for arachidonic acid (76 fold at 15 min) followed by docosahexaenoic acid. Of the acyl-CoA mol ecular species only the concentration of arachidonoyl-CoA was increase d at 3 min and 15 min after decapitation, by 3-4 fold compared with mi crowaved 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 ischem ia, likely at the expense of docosahexaenoic acid.