Effect of delayed induction of postischemic hypothermia on spinal cord damage induced by transient ischemic insult in rabbits.
OBJECTIVE
This study was performed to determine the effect of delayed induction of mild hypothermia after transient spinal cord ischemia in rabbits.


METHODS
Abdominal aortic occlusion was performed for 15 minutes to induce spinal cord ischemia at a rectal temperature of 37.3 +/- 0.3 degrees C. Four groups of rabbits were investigated: Group 1 (n = 8) was subjected to ischemia and reperfused at the same temperature for 7 hours; Group 2 (n = 8) was subjected to ischemia and reperfused at the same temperature for 1 hour, followed by 6 hours of systemic hypothermia (32.5 +/- 0.5 degrees C); Group 3 (n = 8) was subjected to ischemia, reperfusion at the same temperature for 3 hours and then 6 hours of systemic hypothermia (32.5 +/- 0.5 degrees C); and Group 4 (n = 8) comprised non-ischemic controls. Neurological status of all rabbits in Groups 1-3 was recorded and animals were sacrificed 1 week after ischemic injury. Spinal cord sections were examined microscopically to determine the extent of ischemic neuronal damage.


RESULTS
Mean modified Tarlov's score at 1 week after ischemic insult was 0.5 +/- 0.8 in Group 1, compared to 43 +/- 1.5 in Group 2 and 2.9 +/- 1.8 in Group 3. Mean total number of surviving neurons within examined sections of spinal cord was significantly greater for Groups 2 and 3 compared with Group 1 (Group 1, 81 +/- 66.1; Group 2, 293.4 +/- 110.9; Group 3, 227.1 +/- 105.5; p < 0.001).


CONCLUSIONS
Delayed postischemic hypothermia induced within 3 hours after reperfusion significantly reduces ischemia-induced spinal cord neuronal damage in rabbits.
Tsutsumi
Koji
K
Department of Cardiovascular Surgery, Keio University School of Medicine, Tokyo, Japan.
Ueda
Toshihiko
T
Shimizu
Hideyuki
H
Hashizume
Kenichi
K
Yozu
Ryohei
R
D000818:Animals; D007036:Hypothermia, Induced / Q000379:methods*; D011817:Rabbits; D020760:Spinal Cord Ischemia / Q000628:therapy*; D013997:Time Factors; D016896:Treatment Outcome