Effect of ischemia and reperfusion on oxidative processes in the large colon and jejunum of horses.
OBJECTIVE
To evaluate and compare oxidative processes during ischemia and reperfusion of the equine large colon and jejunum.


METHODS
2 groups of 6 anesthetized horses undergoing a terminal procedure.


METHODS
Isolated loops of large colon and jejunum were subjected to 2 hours of ischemia, followed by 2 hours of reperfusion. Tissue specimens were taken after 105 minutes of ischemia and 10, 30, 60, and 120 minutes of reperfusion. Mesenteric arterial and venous blood samples were collected for blood gas analysis at the same times to evaluate ischemia and reoxygenation. Oxidative processes in tissues were evaluated by use of biochemical assays for malondialdehyde and conjugated dienes and by use of the manganese-diaminobenzidine histochemical technique for localized superoxide generation.


RESULTS
Significant quantities of malondialdehyde and conjugated dienes were detected in the jejunum after 60 and 120 minutes of reperfusion together with histochemical evidence of superoxide generation in jejunal endothelial cells and in submucosal neutrophils and eosinophils.


CONCLUSIONS
Oxidative processes do not appear to have an appreciable role in inducing damage in the equine large colon during reperfusion after 2 hours of ischemia. In contrast to the jejunum, reactive oxygen species are not generated in measurable quantities in the large colon subsequent to ischemia and reperfusion.


CONCLUSIONS
Free radical scavengers are not likely to be effective in prevention of equine colonic mucosal deterioration after ischemia.
Kooreman
K
K
Department of Basic Medical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907-1246, USA.
Babbs
C
C
Fessler
J
J
D000818:Animals; D001639:Bicarbonates / Q000097:blood; D002245:Carbon Dioxide / Q000097:blood; D003106:Colon / Q000098:blood supply* / Q000378:metabolism; D006439:Hemodynamics; D006736:Horses; D066298:In Vitro Techniques; D007511:Ischemia / Q000378:metabolism* / Q000503:physiopathology; D007583:Jejunum / Q000098:blood supply* / Q000378:metabolism; D008315:Malondialdehyde / Q000032:analysis; D008638:Mesenteric Arteries; D008642:Mesenteric Veins; D009130:Muscle, Smooth / Q000098:blood supply* / Q000378:metabolism; D018384:Oxidative Stress; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D015424:Reperfusion; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
D001639:Bicarbonates; D017392:Thiobarbituric Acid Reactive Substances; D002245:Carbon Dioxide; D008315:Malondialdehyde; D010100:Oxygen