Paraplegia or paraparesis caused by temporary cross-clamping of the ao
rta is a devastating sequela in patients after surgery of the thoracoa
bdominal aorta. No effective clinical method is available to protect t
he spinal cord from ischemic reperfusion injury. A small animal (rat)
model of spinal cord ischemia is established to better understand the
pathophysiological events and to evaluate potential treatments. Eighty
-one male Sprague-Dawley rats weighing 300 g to 350 g were used for mo
del development (45) and treatment evaluation (36). The heparinized an
d anesthetized rat was supported by a respirator following tracheostom
y. The thoracic aorta was cannulated via the left carotid artery for p
ost-damping intra-aortic treatment solution administration. After thor
acotomy, the aorta was freed and temporarily clamped just distal to th
e left subclavian artery and just proximal to the diaphragm for differ
ent time intervals: 0, 5, 10, 15, 20, 25, 30, 35 and 40 minutes (five
animals per group). The motor function of the lower extremities postop
eratively showed consistent impairment after 30 minutes clamping (5/5
rats were paralyzed), and this time interval was used for treatment ev
aluation. For each treatment, six animals per group were used, and dir
ect local intra-aortic infusion of physiologic solution (2 mL) at diff
erent temperatures with or without buffer substances was given immedia
tely after double crossclamp to protect the ischemic spinal cord. Arte
rial blood (2 mL) was infused in the control group. The data indicate
that the addition of HCO3-(20 mM) to the hypothermic (15 degrees C) so
lution offered complete protection of the spinal cord from ischemic in
jury. We conclude that this clinically applicable treatment warrants f
urther investigation for the development of a ''neuroplegic solution''
for the protection of the ischemic spinal cord during repair of the t
horacoabdominal aorta. Additionally, this report describes a technical
ly easy and reproducible model of spinal cord ischemia suitable for ev
aluating other therapies.