Effects of ischemia and reperfusion on production of nitrotyrosine, activation of eosinophils, and apoptosis in the large colonic mucosa of horses.
OBJECTIVE
To assess the effects of ischemia and reperfusion on indicators of oxidative stress, activation of eosinophils, and apoptosis in the large colonic mucosa of horses.


METHODS
40 horses.


METHODS
In 1 or two 20-cm-long segments of the pelvic flexure, ischemia was induced for 1 or 2 hours followed by no reperfusion or 30 minutes and 18 hours of reperfusion in anesthetized horses. Mucosal specimens were collected before (controls; n = 20 horses) and after each period of ischemia, and full-thickness tissue samples were collected after each period of reperfusion. Sections of colonic tissues were stained for histomorphometric analysis or assessment of eosinophil accumulation. Nitrotyrosine was identified immunohistochemically, and severity of apoptosis was determined via the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling method.


RESULTS
Numbers of mucosal eosinophils were similar before induction of ischemia, after ischemia, and after ischemia-reperfusion. Eosinophil nitrotyrosine production increased significantly during ischemia and continued through 30 minutes of reperfusion; production was decreased at 18 hours of reperfusion but remained greater than that of the controls. In other leukocytes, nitrotyrosine generation peaked at 1 hour of ischemia and again at 18 hours of reperfusion. Compared with control findings, epithelial apoptosis increased gradually at 1 through 2 hours of ischemia with no further progression after reperfusion.


CONCLUSIONS
Results suggested that resident eosinophils in the large colon of horses react to mucosal injury from ischemia and reperfusion and may undergo oxidative stress under those conditions. Epithelial apoptosis could contribute to tissue damage.
Island Whirl Equine Colic Research Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610, USA. agrosche@.ufl.edu
Astrid
A
Grosche
David E
DE
Freeman
Alison J
AJ
Morton
Maximilian M R
MM
Polyak
Sarah A
SA
Matyjaszek
D000818:Animals; D017209:Apoptosis; D003106:Colon / Q000166:cytology / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D003108:Colonic Diseases / Q000276:immunology / Q000378:metabolism / Q000503:physiopathology / Q000662:veterinary*; D004804:Eosinophils / Q000166:cytology; D005260:Female; D006734:Horse Diseases / Q000276:immunology / Q000378:metabolism / Q000503:physiopathology*; D006736:Horses; D020287:In Situ Nick-End Labeling / Q000662:veterinary; D007413:Intestinal Mucosa / Q000276:immunology / Q000293:injuries / Q000378:metabolism / Q000473:pathology*; D007511:Ischemia / Q000378:metabolism / Q000503:physiopathology / Q000662:veterinary*; D008297:Male; D008855:Microscopy, Electron, Scanning / Q000662:veterinary; D018384:Oxidative Stress; D011897:Random Allocation; D015427:Reperfusion Injury / Q000378:metabolism / Q000503:physiopathology / Q000662:veterinary*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
C002744:3-nitrotyrosine; D014443:Tyrosine