Expression and Function of Inducible Nitric Oxide Synthase during Rat Colon Anastomotic Healing

David Thomas Efron, Frank J. Thornton, Christina Steulten, Udaya S. Tantry, Maria B. Witte, Teruo Kiyama, Adrian Barbul

Research output: Contribution to journalArticle

Abstract

Nitric oxide plays a significant but incompletely understood role in fibroblast function and cutaneous wound collagen synthesis; however, the participation of inducible nitric oxide synthase (iNOS) in gastrointestinal anastomotic healing has not been studied. Male Sprague-Dawley rats underwent single-layer left colonic anastomosis. Animals were killed at 24-hour intervals postoperatively and the anastomosis was excised. Parallel uninjured colon tissue samples were also analyzed. Reverse transcriptase-polymerase chain reaction confirmed the absence of iNOS messenger RNA in control colon and expression of the gene in anastomotic tissue on all study days. Northern hybridization demonstrated maximal iNOS messenger RNA transcription on day 1 with decreased levels on days 3 and 5. iNOS enzyme activity, measured biochemically by the conversion of [3H]-arginine to [3H]-citrulline ex vivo, was also maximal on day 1 (7.35 ± 1.34 pmol/mg protein/min [± standard error of the mean], n = 10) and decreased on days 3 (4.37 ± 2.32 pmol/mg protein/min; n = 6) and 5 (2.80 ± 0.92 pmol/mg protein/min; n = 6). Immunohistochemical staining demonstrated that (1) iNOS expression is confined to a discrete cell population in the region of the anastomosis containing inflammatory cells; (2) those cells assume a highly conserved position on the luminal edge of the proliferating scar; and (3) the iNOS-expressing cells are present throughout the fibroplastic phase of healing. To functionally assess the role of iNOS in colonic healing, rats were treated with a continuous intravenous infusion of S-methylisothiourea (a selective inhibitor of iNOS) at a dosage of 200 mg/kg/day for 5 days after anastomosis. There was a significantly reduced anastomotic bursting pressure in rats treated with the inhibitor as compared to rats treated with intravenous normal saline solution (108.4 ± 13.2 mm Hg vs. 148.4 ± 10.3 mm Hg; P

Original languageEnglish (US)
Pages (from-to)592-601
Number of pages10
JournalJournal of Gastrointestinal Surgery
Volume3
Issue number6
Publication statusPublished - Nov 1999

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Keywords

  • Colon anastomosis
  • Nitric oxide
  • Wound healing

ASJC Scopus subject areas

  • Surgery

Cite this

Efron, D. T., Thornton, F. J., Steulten, C., Tantry, U. S., Witte, M. B., Kiyama, T., & Barbul, A. (1999). Expression and Function of Inducible Nitric Oxide Synthase during Rat Colon Anastomotic Healing. Journal of Gastrointestinal Surgery, 3(6), 592-601.