Identification and quantitative analysis of hydroxy-eicosatetraenoic acids in rat brains exposed to regional ischemia.

To clarify possible roles in the pathogenesis of ischemic brain edema, identification and quantitative analysis of hydroxy-eicosatetraenoic acids (HETEs) in rat brains exposed to middle cerebral artery occlusion were carried out using high-performance liquid chromatography. Rat brain sampling was done by in situ freezing 24 and 72 hours after occlusion. Only a small amount of 15-HETE was found in control rat brains. Twenty-four hours after ischemia, 11-HETE appeared, and the amount of 15-HETE tended to increase. Seventy-two hours after ischemia, when brain edema reached its maximum, 5-, 8-, 9-, 11-, 12-, and 15-HETEs were identified, and the amounts of all HETEs except 8- and 12-HETE were significantly increased. The detection of 5-HETE in ischemic rat brain indicates the simultaneous production of leukotrienes in the same brain area. The above results support the view that lipoxygenase products may play significant roles in the formation of ischemic brain edema.