Effect of parenteral zinc sulfate on colon anastomosis repair in the rat

Background and aims To prevent colonic anastomotic dehiscence, pharmaceutical interventions should inhibit degradation of existing submucosal collagen fibers and accelerate the synthesis of new collagen molecules. Zinc has multiple functions in collagen metabolism and was recently found beneficial in colonic anastomosis repair. We have investigated the effect of daily intraperitoneal zinc (2 mg/kg) injections on the development of the biomechanical integrity of left colon anastomoses. Materials and methods Sixty Sprague-Dawley male rats (median 245 g) were allocated to treatment with zinc sulfate in saline (n=30) or with saline alone (n=30) starting 1 h before the anastomoses were made. Serum zinc levels and anastomotic breaking strength were determined on postoperative days 3 (n=30) and 7 (n=30). The initial breaking strength or suture-binding capacity was determined in additional ten non-treated animals (277 g). Results The breaking strength of the anastomoses decreased in the two groups combined (n=30) by 50% (p < 0.001) on day 3 but was regained by postoperative day 7 compared with the initial anastomotic biomechanical strength. Serum zinc levels also increased from day 3 to day 7 in both intervention groups and correlated significantly with breaking strength (r=0.57, p<0.001). Although the median serum zinc level was 14% higher (p<0.01) on day 7 in zinc-treated than in saline-treated animals, the breaking strength did not differ significantly between zinc-treated and saline-treated rats on either day 3 (p=0.95) or day 7 (p=0.70). Conclusion In contrast to previous report in rabbits, we failed to demonstrate the beneficial effects of parenteral zinc supplementation on colon anastomosis repair in a rat model.