Sevoflurane pre- and post-conditioning protect the brain via the mitochondrial K ATP channel.

Background: This study aimed to evaluate whether exposure to sevoflurane at the onset of reperfusion provides protection similar to sevoflurane preconditioning and whether the effect depends on mitochondrial potassium ATP-dependent channel (mitoK(ATP)) in a rat model of focal cerebral ischaemia.
Methods: Adult Wistar male rats were subjected to focal cerebral ischaemia for 1 h followed by 24 h or 7 days of reperfusion. Preconditioning consisted of 15 min exposure to sevoflurane at 1 minimum alveolar concentration (2.6%) 72 h before ischaemia. Post-conditioning was performed by exposure to sevoflurane immediately at the onset of reperfusion or by a delayed exposure 5 min after the onset of reperfusion. The role of the mitoK(ATP) channel was assessed by i.p. injection of the selective blocker 5-hydroxydecanoate before each sevoflurane administration or by the mitoK(ATP) channel opener, diazoxide (DZX), given in place of sevoflurane. Cerebral infarct size, neurological deficit score, and motor coordination were evaluated 24 h and 7 days after reperfusion.
Results: Sevoflurane preconditioning and early post-conditioning reduced both cerebral infarct size and neurological defect score at 24 h of reperfusion whereas the sole sevoflurane post-conditioning improved motor coordination. At 7 days, only infarct volume remained lower in pre- and post-conditioned animals. Neuroprotection mediated by sevoflurane was lost when it was given 5 min after the onset of reperfusion and was abolished by inhibition of mitoK(ATP). DZX alone mimicked sevoflurane-induced pre- and post-conditioning.
Conclusions: The pretreatment with sevoflurane or its early administration at reperfusion provides neuroprotection via mitoK(ATP) in a rat model of focal cerebral ischaemia.