Isoflurane provides long-term protection against focal cerebral ischemia in the rat.
BACKGROUND
Long-term neuroprotection by isoflurane has been questioned. The authors examined factors in experimental models potentially critical to definition of enduring isoflurane neuroprotection.


METHODS
Rats were prepared for temporary middle cerebral artery occlusion (MCAO). Pericranial normothermia was maintained. Neurologic deficits (range, 0-48; 0=no deficit) and cerebral infarct volumes were measured. In experiment 1, rats underwent 50 or 80 min MCAO while awake or anesthetized with 1.8% isoflurane. Blood pressure was controlled with phenylephrine. Outcome was evaluated 2 weeks later. In experiment 2, rats underwent 50 min MCAO while awake or anesthetized with isoflurane, with outcome evaluated 8 weeks later. In experiment 3, rats underwent 50 min MCAO while awake or anesthetized with isoflurane and 2 weeks recovery. Effects of phenylephrine and the mitochondrial adenosine triphosphate-sensitive K channel antagonist 5-hydroxydecanoate were studied. In experiment 4, isoflurane-anesthetized rats underwent 50 min MCAO with permanent or temporary common carotid artery occlusion, with outcome evaluated 2 weeks later.


RESULTS
In experiment 1, isoflurane reduced neurologic deficit (median+/-interquartile range; awake vs. isoflurane: 11+/-12 vs. 8+/-6 for 80 min and 13+/-4 vs. 3+/-9 for 50 min; P=0.0006) and infarct size (160+/-97 vs. 84+/-62 mm for 80 min and 169+/-78 vs. 68+/-61 mm for 50 min; P<0.0001). In experiment 2, isoflurane protection persisted at 8 weeks after ischemia. In experiment 3, there was no effect of phenylephrine or 5-hydroxydecanoate. In experiment 4, permanent common carotid ligation increased infarct size threefold versus temporary occlusion.


CONCLUSIONS
Isoflurane repeatedly improved long-term neurologic and histologic outcome from focal ischemia independent of ischemia duration, perfusion pressure, or pretreatment with 5-hydroxydecanoate.
Sakai
Hiroaki
H
Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA.
Sheng
Huaxin
H
Yates
Robert B
RB
Ishida
Kazuyoshi
K
Pearlstein
Robert D
RD
Warner
David S
DS
D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002545:Brain Ischemia / Q000517:prevention & control*; D020244:Infarction, Middle Cerebral Artery / Q000188:drug therapy; D007530:Isoflurane / Q000494:pharmacology*; D008297:Male; D018696:Neuroprotective Agents / Q000494:pharmacology*; D015221:Potassium Channels / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar
D018685:Anesthetics, Inhalation; D018696:Neuroprotective Agents; D015221:Potassium Channels; C117780:mitochondrial K(ATP) channel; D007530:Isoflurane