Healing of experimental colonic anastomoses: III. Collagen metabolism in the colon after left colon resection

In a previous study it was shown that resection and anastomosis of the left colon is accompanied by a marked reduction of collagen concentration in the colon. These changes were not confined to the immediate vicinity of the anastomosis but extended a considerable distance along the bowel and were more marked proximally than distally. Whether the decrease in collagen concentration is due to decreased synthesis or increased breakdown of collagen was studied in the present work by measuring the rate of collagen synthesis and comparing the observations with changes in net amounts of collagen.Synthesis of collagen was studied using pulse labeling with ³H-proline. Studies on the time course of incorporation showed a biphasic pattern with maximal specific activities of collagen 4 and 24 hours after injection of the precursor. The maximal labeling occurred after 24 hours. At that time 75 to 90 percent of the label was present in insoluble collagen, indicating a high rate of turnover. Comparison of net amounts with the rate of synthesis indicates an increased breakdown of collagen. The reaction was clearly most pronounced proximal to the anastomosis. During the first 4 postoperative days breakdown (lysis) dominated. On the 7th day increased net amounts of collagen indicate that synthesis had begun to outbalance processes that break down collagen. The results indicate that the entire colon reacts to the trauma of resection and anastomosis and that in healing of the colon a delicate balance exists between the synthesis and breakdown of collagen.