Background. Ischemic preconditioning (IPC) is an endogenous cellular protec
tive mechanism whereby brief, noninjurious periods of ischemia render a tis
sue more resistant to a subsequent, more prolonged ischemic insult. We hypo
thesized that IPC of the spinal cord would reduce neurologic injury after e
xperimental aortic occlusion in rats and that this improved neurologic bene
fit could be induced acutely after a short reperfusion interval separating
the IPC and the ischemic insult.
Methods. Forty male Sprague-Dawley rats under general anesthesia were rando
mly assigned to one of two groups. The IPC group (n = 20) had 3 minutes of
aortic occlusion to induce spinal cord ischemia 30 minutes of reperfusion,
and 12 minutes of ischemia, whereas the controls (n = 20) had only 12 minut
es of isehemia. Neurologic function was evaluated 24 and 48 hours later. So
me animals from these groups were perfusion-fixed for hematoxylin and eosin
staining of the spinal cord for histologic evaluation.
Results. Survival was significantly better at 48 hours in the IPC group. Se
nsory and motor neurologic function were significantly different between gr
oups at 24 and 48 hours. Histologic evaluation at 48 hours showed severe ne
urologic damage in rats with poor neurologic test scores.
Conclusions. Ischemic preconditioning reduces neurologic injury and improve
s survival in a rat model of spinal cord ischemia. The protective benefit o
f IPC is acutely invoked after a 30-minute reperfusion interval between the
preconditioning and the ischemic event. (Ann Thorac Surg 1999;68:874-80) (
C) 1999 by The Society of Thoracic Surgeons.