Attenuation by pentobarbital of free fatty acid and diacylglycerol liberation during global ischaemia in rat brain.

The effects of global ischaemia and pentobarbital upon lipid metabolism were studied in the rat brain. Brain ischaemia was evoked by rat decapitation. Pentobarbital (60 mg/kg) was administered i.p. for 15 min prior to decapitation. The removed brains were incubated for 1, 5, 15 or 30 min at 37 degrees C and then quickly frozen in liquid nitrogen. After extraction of lipids from the brains, neutral lipid and phospholipid compositions were analysed by thin-layer and gas-liquid chromatography. The results demonstrated that free fatty acids (FFAs), either unsaturated or saturated, rapidly accumulated in the brain during the early period of ischaemia but attenuated significantly with pentobarbital pretreatment. Pentobarbital repressed the accumulations of stearate and arachidonate, with little effect on palmitate and oleate liberation. Diacylglycerols (DG) also were produced in the ischaemic brain, and their acyl chain composition was similar to that of liberated FFAs. However, the increase of DG was inhibited by pentobarbital anaesthesia. In particular, pentobarbital attenuated the formation of DG enriched in arachidonate and stearate. The fatty acyl composition of DG resembled that of phosphatidylinositol. These observations suggest that pentobarbital somehow may alter phospholipase C activity and influence inositol phospholipid breakdown during ischaemia, and this effect would be a membrane stabilizing action of pentobarbital.