COMPARISON OF OXIDATIVE-PHOSPHORYLATION IN THE ANASTOMOSIS OF THE SMALL AND LARGE-BOWEL - AN EXPERIMENTAL-STUDY IN THE RABBIT

Dehiscence of anastomosis in the large bowel (LB) is more frequent com pared with that in the small bowel(SB). The pathophysiological mechani sms underlying the phenomenon are well known. The goal of this study i s to demonstrate the different oxidative phosphorylation roles in the response of the anastomosed SB and LB. In 45 male rabbits under genera l anaesthesia, the ileum and colon were transected always on the same side and an end-to-end anastomosis was constructed using single-layer inverting interrupted 5-0 Ethilon sutures. Tracts containing bowel ana stomoses were collected at 3, 12 and 24 h and 3, 7 and 21 days after t he operation and compared with non-anastomosed bowel. Respiratory rate s with different substrates, enzymatic activities, respiratory complex structures and cytochrome contents were measured in smooth muscle pur ified mitochondria. Mitochondrial respiration showed significant diffe rences in the LB versus anastomosed SB: respiratory rates were markedl y reduced in the LB (residual activity: 25 vs. 95% of the SB). Detaile d analysis of other mitochondrial parameters confirmed a better tolera nce of the ileum to anastomosis. From these preliminary studies we can consider two different aerobic thresholds for either the large or the small rabbit intestine, the latter being oxygen dependent. This can e xplain the mitochondrial sufferance of anastomosis in the LB whose pre valent aerobic metabolism can be more easily affected by different nox ae if compared with the tendency to glycolytic metabolism of the small intestine.