Epidural cooling minimizes spinal cord injury after aortic cross-clamping through induction of nitric oxide synthase.
BACKGROUND
By using a U-shaped lumen catheter, the authors examined the effects of epidural cooling on spinal cord injury after aortic cross-clamping (ACC), with a focus on changes of spinal cord blood flow and expression of inducible nitric oxide synthase.


METHODS
Sixteen pigs were randomized into two groups: Control group (n = 8) or Cooling group (n = 8). In the latter, epidural cooling started at 30 min (baseline) before 45 min of ACC and persisted for the next 30 min of reperfusion period. Spinal cord blood flow and somatosensory-evoked potentials were assessed during peri-ACC period. At 48 h, we evaluated hind limb function by using Tarlov score and expression of inducible nitric oxide synthase on spinal cord using immunohistochemistry.


RESULTS
After ACC, spinal cord blood flow dropped to a similar extent in both groups. During the reperfusion period, spinal cord blood flow increased up to 113% (103-124%), median (interquartile range), level transiently and decreased to 32% (22-47%) level versus baseline in the Control group, whereas it increased and remained at 92% (86-97%) level in the Cooling group. Simultaneously, somatosensory-evoked potentials showed that onset of loss time was delayed and recovery time was shortened in the Cooling group. Tarlov scores in the Cooling group were significantly higher and accompanied by normal-appearing motor neurons and significantly greater expression of inducible nitric oxide synthase on spinal cord versus the Control group.


CONCLUSIONS
This study shows that epidural cooling during ACC minimized the risk of spinal cord injury, possibly by preventing delayed hypoperfusion and upregulating inducible nitric oxide synthase expression.
Ishikawa
Akiko
A
Department of Anesthesiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, Japan.
Mori
Atsuo
A
Kabei
Nobuyuki
N
Yoshitake
Akihiro
A
Suzuki
Takeshi
T
Katori
Nobuyuki
N
Morisaki
Hiroshi
H
Yozu
Ryohei
R
Takeda
Junzo
J
D000818:Animals; D001013:Aorta, Thoracic / Q000502:physiology; D003080:Cold Temperature; D003250:Constriction; D004824:Epidural Space / Q000473:pathology / Q000502:physiology*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D006614:Hindlimb / Q000502:physiology; D007150:Immunohistochemistry; D008297:Male; D009068:Movement / Q000502:physiology; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis* / Q000235:genetics; D012039:Regional Blood Flow / Q000502:physiology; D013116:Spinal Cord / Q000098:blood supply / Q000201:enzymology / Q000473:pathology; D013119:Spinal Cord Injuries / Q000201:enzymology* / Q000473:pathology / Q000628:therapy*; D013552:Swine
D052247:Nitric Oxide Synthase Type II