Mismatch recovery of regional cerebral blood flow and brain temperature during reperfusion after prolonged brain ischemia in gerbils.
BACKGROUND
Recovery of cerebral reperfusion after stroke or cardiac arrest can take a long time. We aimed to identify differences in the postischemic recovery of physiologic parameters between short and prolonged brain ischemia.


METHODS
Eighteen Mongolian gerbils were assigned to one of three groups: 5-minute (G5), 15-minute (G15), or 30-minute (G30) ischemia. With the use of our original microspectroscopy system, global ischemic reperfusion was performed. We measured changes in regional cerebral blood flow (r-CBF), microvessel diameter, and brain temperature (BrT) simultaneously. We also monitored somatosensory evoked potentials (SEPs) to evaluate electrophysiologic response.


RESULTS
Both G5 and G15 showed concurrent recovery of r-CBF and BrT with hyperemia and hyperthermia, respectively, 10 to 15 minutes after reperfusion. The increase in BrT was <1 degree C and recovered to baseline within 60 minutes after reperfusion. In G30, recovery of r-CBF was significantly delayed relative to that of BrT. The increase in BrT was >2 degrees C, peaking approximately 15 minutes after reperfusion, and then maintained increases of >1 degree C for 120 minutes. SEPs in G5 and G15 showed concomitant recovery with that of r-CBF, whereas SEP recovery in G30 was delayed relative to that of r-CBF, eventually disappearing. All except one of the G30 gerbils died within 24 hours, but all in G5 and G15 survived.


CONCLUSIONS
These results suggest that mismatch recovery of r-CBF and BrT after prolonged ischemia initiates metabolic derangement in brain tissue, leading to the electrochemical dysfunction and mortality.
Tajima
Goro
G
Departments of Traumatology and Acute Critical Medicine, Osaka University Graduate School of Medicine, Osaka, Japan. tajima@emerg-hp.osaka-u.ac.jp
Shiozaki
Tadahiko
T
Seiyama
Akitoshi
A
Mohri
Tomoyoshi
T
Kajino
Kentaro
K
Nakae
Haruhiko
H
Tasaki
Osamu
O
Ogura
Hiroshi
H
Kuwagata
Yasuyuki
Y
Tanaka
Hiroshi
H
Shimazu
Takeshi
T
Sugimoto
Hisashi
H
D000704:Analysis of Variance; D000818:Animals; D001831:Body Temperature; D002545:Brain Ischemia / Q000209:etiology / Q000628:therapy*; D002560:Cerebrovascular Circulation; D005073:Evoked Potentials, Somatosensory; D005849:Gerbillinae; D006323:Heart Arrest / Q000150:complications / Q000628:therapy*; D007036:Hypothermia, Induced; D008297:Male; D015427:Reperfusion Injury / Q000503:physiopathology* / Q000517:prevention & control*; D016019:Survival Analysis; D013997:Time Factors