Neutropenia prevents decrease in strength of rat intestinal anastomosis: partial effect of oxygen free radical scavengers and allopurinol.

A marked decrease in strength, probably due to local collagenolysis, occurs early after surgery in tissues adjacent to an incisional wound. To examine the role of the neutrophils, antineutrophil serum (ANS) was given to rats before and after a standardized end-to-end ileoileal anastomosis. Preimmune serum (PIS) was given to control rats. The decrease in anastomotic breaking strength, amounting to 55% in the PIS group, did not occur in ANS-treated rats, in which there was a decrease by more than 95% in the number of circulating polymorphonuclear cells. The decrease in tissue strength seems to be partly from oxygen free radicals, since the free radical scavengers superoxygen dismutase (SOD) and catalase prevented approximately 50% of the decrease. The xanthine oxidase inhibitor, allopurinol, prevented approximately 30% of the decrease. This is consistent with oxygen free radicals being partly generated by the neutrophils and partly generated after conversion of tissue xanthine dehydrogenase to xanthine oxidase. In contrast to ANS, SOD and catalase were unable to fully prevent the decrease in breaking strength. Therefore some other factor in addition to oxygen free radicals should be involved. One such factor may be the release of collagenolytic proteinases, e.g., elastase and cathepsin G, from the neutrophils.