Morphologic changes and xanthine oxidase activity in the equine jejunum during low flow ischemia and reperfusion

Nicholas J. Vatistas From the Comparative Gastroenterology Laboratory (Vatistas, Snyder, Nieto, Woliner, Harmon), the Department of Surgical and Radiological Sciences (Hildebrand), the Rowe Program in Genetics (Barry), and the Department of Statistics (Drake), University of California, Davis, CA 95616.

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Jack R. Snyder From the Comparative Gastroenterology Laboratory (Vatistas, Snyder, Nieto, Woliner, Harmon), the Department of Surgical and Radiological Sciences (Hildebrand), the Rowe Program in Genetics (Barry), and the Department of Statistics (Drake), University of California, Davis, CA 95616.

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Jorge Nieto From the Comparative Gastroenterology Laboratory (Vatistas, Snyder, Nieto, Woliner, Harmon), the Department of Surgical and Radiological Sciences (Hildebrand), the Rowe Program in Genetics (Barry), and the Department of Statistics (Drake), University of California, Davis, CA 95616.

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Susan V. Hildebrand From the Comparative Gastroenterology Laboratory (Vatistas, Snyder, Nieto, Woliner, Harmon), the Department of Surgical and Radiological Sciences (Hildebrand), the Rowe Program in Genetics (Barry), and the Department of Statistics (Drake), University of California, Davis, CA 95616.

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Michael J. Woliner From the Comparative Gastroenterology Laboratory (Vatistas, Snyder, Nieto, Woliner, Harmon), the Department of Surgical and Radiological Sciences (Hildebrand), the Rowe Program in Genetics (Barry), and the Department of Statistics (Drake), University of California, Davis, CA 95616.

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Faye A. Harmon From the Comparative Gastroenterology Laboratory (Vatistas, Snyder, Nieto, Woliner, Harmon), the Department of Surgical and Radiological Sciences (Hildebrand), the Rowe Program in Genetics (Barry), and the Department of Statistics (Drake), University of California, Davis, CA 95616.

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Sean J. Barry From the Comparative Gastroenterology Laboratory (Vatistas, Snyder, Nieto, Woliner, Harmon), the Department of Surgical and Radiological Sciences (Hildebrand), the Rowe Program in Genetics (Barry), and the Department of Statistics (Drake), University of California, Davis, CA 95616.

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Christiana Drake From the Comparative Gastroenterology Laboratory (Vatistas, Snyder, Nieto, Woliner, Harmon), the Department of Surgical and Radiological Sciences (Hildebrand), the Rowe Program in Genetics (Barry), and the Department of Statistics (Drake), University of California, Davis, CA 95616.

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Abstract

Objective

To determine whether xanthine oxidase and dehydrogenase activities are altered during low flow ischemia and reperfusion of the small intestine of horses.

Animals

5 clinically normal horses without histories of abdominal problems.

Procedure

With the horse under general anesthesia, a laparotomy was performed and blood flow to a segment of the distal jejunum was reduced to 20% of baseline for 120 minutes and was then reperfused for 120 minutes. Biopsy specimens were obtained before, during, and after ischemia for determination of xanthine oxidase and dehydrogenase activities, and for histologic and morphometric analyses.

Results

Percentage of xanthine oxidase activity (as a percentage of xanthine oxidase and dehydrogenase activity) was not altered during ischemia and reperfusion. An inflammatory response developed and progressed during ischemia and reperfusion. Mucosal lesions increased in severity after ischemia and reperfusion. Mucosal surface area and volume decreased during ischemia and continued to decrease during reperfusion. Submucosal volume increased slightly during ischemia, and continued to increase during reperfusion.

Conclusions and Clinical Relevance

Evidence for conversion of xanthine dehydrogenase to xanthine oxidase during ischemia was not found. Factors other than production of reactive oxygen metabolites may be responsible for progressive epithelial loss, decrease in mucosal surface area and volume, and increase in submucosal volume observed in this study. Other methods of determining xanthine oxidase activity that detect the enzyme in sloughed epithelial cells should be used to better define the importance of this pathway in jejunal reperfusion injury in horses. (Am J Vet Res 1998;59:772-776)

Abstract

Objective

To determine whether xanthine oxidase and dehydrogenase activities are altered during low flow ischemia and reperfusion of the small intestine of horses.

Animals

5 clinically normal horses without histories of abdominal problems.

Procedure

With the horse under general anesthesia, a laparotomy was performed and blood flow to a segment of the distal jejunum was reduced to 20% of baseline for 120 minutes and was then reperfused for 120 minutes. Biopsy specimens were obtained before, during, and after ischemia for determination of xanthine oxidase and dehydrogenase activities, and for histologic and morphometric analyses.

Results

Percentage of xanthine oxidase activity (as a percentage of xanthine oxidase and dehydrogenase activity) was not altered during ischemia and reperfusion. An inflammatory response developed and progressed during ischemia and reperfusion. Mucosal lesions increased in severity after ischemia and reperfusion. Mucosal surface area and volume decreased during ischemia and continued to decrease during reperfusion. Submucosal volume increased slightly during ischemia, and continued to increase during reperfusion.

Conclusions and Clinical Relevance

Evidence for conversion of xanthine dehydrogenase to xanthine oxidase during ischemia was not found. Factors other than production of reactive oxygen metabolites may be responsible for progressive epithelial loss, decrease in mucosal surface area and volume, and increase in submucosal volume observed in this study. Other methods of determining xanthine oxidase activity that detect the enzyme in sloughed epithelial cells should be used to better define the importance of this pathway in jejunal reperfusion injury in horses. (Am J Vet Res 1998;59:772-776)

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