Anesthesia profoundly impacts peri-
infarct depolarizations (PIDs), but only one prior report has described their monitoring during experimental
stroke in awake animals. Since temporal patterns of PID occurrence are model specific, the current study examined PID incidence during focal
ischemia in the awake Spontaneously Hypertensive Rat (SHR), and documented the impact of both prior and concurrent
isoflurane anesthesia. For awake recordings,
electrodes were implanted under
isoflurane anesthesia 1day to 5weeks prior to occlusion surgery. Rats were then subjected to permanent or transient (2h) tandem occlusion of the middle cerebral and ipsilateral common carotid arteries, followed by PID monitoring for up to 3days. Comparison perfusion imaging studies evaluated PID-associated hyperemic transients during permanent
ischemia under
anesthesia at varied intervals following prior
isoflurane exposure. Prior
anesthesia attenuated PID number at intervals up to 1week, establishing 2weeks as a practical recovery duration following surgical preparation to avoid
isoflurane preconditioning effects. PIDs in awake SHR were limited to the first 4h after permanent occlusions. Maintaining
anesthesia during this interval reduced PID number, and prolonged their occurrence through several hours following
anesthesia termination. Although PID number otherwise correlated with
infarct size, PID suppression by
anesthesia was not protective in the absence of reperfusion. PIDs persisted up to 36h after transient occlusions. These results differ markedly from the one previous report of such monitoring in awake Sprague-Dawley rats, which found an extended biphasic PID time course during 24h after both permanent and transient filament occlusions. PID occurrence closely reflects the time course of
infarct progression in the respective models, and may be more useful than absolute PID number as an index of ongoing pathology.