Beneficial effect of proteinase inhibitors on early breaking strength of intestinal anastomoses.

Rats were subjected to end-to-end anastomosis of the small intestine. The breaking strength was measured in different groups immediately after suture and after 24, 72 and 120 h. Tiopronin (Thiola), soya-bean trypsin inhibitor (STI), or saline solution, was given by continuous intravenous infusion during the test periods. In the saline groups there was a marked decrease in breaking strength at 24 and 72 h. Most of the strength was restored at 120 h. The metalloproteinase inhibitor tiopronin, which in a previous study had diminished the decrease in breaking strength at 24 h, was without effect at 72 h. Rats given STI, which is a group-specific serine proteinase inhibitor, had substantially higher values of breaking strength than saline-treated controls at 24 and 72 h. At 120 h no difference was found. Since the postoperative decrease in breaking strength could be attenuated by proteinase inhibitors, it seems to be due to proteinase activities. STI-treatment did not impair subsequent gain in mechanical strength during the fibroplasia period.