Sevoflurane-induced delayed neuroprotection involves mitoK(ATP) channel opening and PKC ε activation

There is an increasing body of evidence that a brief exposure to anesthesia induces ischemic tolerance in rat brain (anesthetic preconditioning). However, it is unknown whether preconditioning with sevoflurane, a commonly used volatile anesthetic in current clinical practice, produces a delayed window of neuroprotection against ischemia and what the mechanisms are for this protection. To address these issues, adult male Sprague-Dawley rats were subjected to middle cerebral arterial occlusion (MCAO) for 2 h. Sevoflurane preconditioning was induced 24 h before brain ischemia by exposing the animals to sevoflurane at 1.0 minimum alveolar concentration (2.4%) in oxygen for 60 min. Animals preconditioned with sevoflurane had lower neurological deficit scores and smaller brain infarct volumes than animals with brain ischemia at 6 and 24 h after MCAO, respectively. Application of a selective antagonist for mitochondrial ATP-sensitive potassium (mitoK(ATP)) channel, 5-hydroxydecanoate (5-HD, 40 mg/kg i.p.) 30 min before sevoflurane exposure attenuated this beneficial effect. Moreover, protein kinase C ε (PKC ε) was translocated to the membrane fraction at 6 h, but not 24 h, after brain reperfusion in animals preconditioned with sevoflurane and this effect was also abolished by 5-HD. We concluded that sevoflurane preconditioning induces a delayed neuroprotection and that mitochondrial K(ATP) channels and PKC ε may be involved in this neuroprotection.