INTRAABDOMINAL SEPSIS IMPAIRS COLONIC REPARATIVE COLLAGEN-SYNTHESIS

BACKGROUND: Intra-abdominal infection is generally considered a contra indication to primary colon anastomosis. In order to elucidate the mec hanisms by which sepsis affects colonic healing, we studied anastomoti c new collagen and protein synthesis and collagen gene expression in a relevant animal model. METHODS: Forty male Sprague-Dawley rats (240 t o 260 g) underwent sham laparotomy (SHAM, n = 18) or cecal ligation an d single puncture (CLP, n = 22). After 24 hours, animals underwent sin gle-layer left colon anastomosis. Animals were sacrificed either 1 dr 4 days postanastomosis. Anastomotic segments of colon were excised, mi nced, and incubated with 4.5 mu Ci H-3-proline. After 3 hours, tissue H-3-proline incorporation was quantitated as an index of total new pro tein synthesis. The protein fraction was then digested with purified c ollagenase enzyme to determine H-3-proline incorporation into collagen ase-digestible protein, an index of new collagen synthesis. Total RNA was extracted from anastomotic tissue samples and subjected to Norther n blot analysis for type I and type III collagen genes. RESULTS: Intra -abdominal sepsis resulted in markedly less new collagen synthesis 1 d ay postanastomosis (9,163 +/- 1,234 versus 3,744 +/- 444 disintegrates per minute H-3-proline/mg of protein, P <0.0001) and 4 days postanast omosis (8,462 +/- 956 versus 5,708 +/- 802 dpm/mg of protein P <0.05). Noncollagenous protein synthesis was also impaired in anastomotic tis sue from CLP rats on postanastomosis day 1 (37,497 +/- 3,740 versus 18 ,593 +/- 2,695 dpm/mg protein, P <0.001) and postanastomosis day 4 (28 ,238 +/- 834 versus 17,784 +/- 1,415 dpm/mg of of protein, P <0.0001). The expression of type I and type III collagen was altered relative t o the normal temporal sequence observed in SHAM animals. CONCLUSION: I ntra-abdominal infection impairs colonic reparative collagen and prote in synthesis. In addition, regulation of type I and type III collagen genes is altered by intra-abdominal sepsis, and the alteration likely contributes to impaired new collagen synthesis and decreased colonic m echanical strength.