Decrease in collagenous proteins and mechanical strength of distal colon after diverting colostomy in rats

The effects of a diverting colostomy on weight, collagen content, and biomechanical strength of the left colon was investigated in rats. Female rats received either a diverting colostomy or a sham-operation and were killed randomly 1, 2, 4, or 12 weeks after surgery. The dry weight and hydroxyproline content of excluded colon decreased by 37% (P < 0.001, confidence limits (CL) = 21-53%) and 25% (P < 0.001, CL = 18-31%), respectively, after 4 weeks, and by 52% (P < 0.001, CL = 38-66%) and 40% (P < 0.001, CL = 27-53%), respectively, after 12 weeks compared to sham-operated rats. The breaking strength of the defunctioned colon decreased by 21% (P < 0.05, CL = 2-40%) after 4 weeks and by 25% after 12 weeks (P < 0.05, CL = 4-46%). The tensile strength of defunctioned colon (load per unit collagen) was reduced by 19% after 4 weeks (P < 0.05, CL = 6-32%). Proximal to the colostomy site we found no differences in the hydroxyproline content or biomechanical strength. In conclusion, defunctioning of the left colon in rats leads to deterioration in the biomechanical properties caused by a lesser content and a decreased quality in the collagen of the left colon.