Relationship between cerebral energy failure and free fatty acid accumulation following prolonged brain ischemia.

Prolonged ischemia by bilateral carotid artery ligation in rats resulted in cerebral edema with a reduced energy state. Mitochondria isolated from the ischemic brain showed an impairment of oxidative phosphorylation. The ischemic brain was also characterized by remarkable accumulation of free fatty acids known to have properties as an uncoupling factor. The major components of increased free fatty acids were palmitic, stearic, oleic and arachidonic acids. The analysis of saponified myelin and mitochondrial lipids from the ischemic brain showed a decrease in fatty acid contents. The main components of decreased fatty acids in these subcellular fractions corresponded to those of free fatty acids accumulating in the ischemic brain. These results indicate that cerebral energy failure in the ischemic brain is related to the accumulation of free fatty acids, which are derived from endogenous brain lipids.