Abstracts
1999 Digestive Disease Week

# 2164 THE EFFECT OF MASSIVE SMALL BOWEL RESECTION ON THE BAX/BCL-W RATIO AND ENTEROCYTE APOPTOSIS
L E Stern, R A Falcone Jr, C J Kemp, L S Stuart, C R Erwin, B W Warner, Children's Hosp Med Ctr, Univ of Cincinnati, Cincinnati, OH

Following massive small bowel resection (SBR), the remaining intestine compensates by a process termed adaptation. Increased rates of enterocyte proliferation are counterbalanced by increased rates of enterocyte apoptosis via mechanisms not well characterized. This study was designed to test the hypothesis that the ratio between bax, a pro-apoptotic gene, and bcl-w, a pro-survival gene, influences the intestinal crypt apoptotic rate following SBR. Methods - Mice (C57B1/6; n=55) underwent a 50% proximal SBR or sham operation (bowel transection/reanastomosis). After 1, 2 and 3 days, the remnant ileum was removed, apoptotic index (number of apoptotic bodies per crypt) recorded and expression of mRNA for bax and bcl-w determined by RNA protection assay. Results - Rates of apoptosis were significantly increased following SBR on each day measured (A). The ratio of bax/bcl-w mRNA expression relative to sham demonstrated an initial increase after SBR but then decreased below baseline by day 3 (B). Conclusions - While an augmented ratio of bax/bcl-w expression corresponds with the initial increase in enterocyte apoptosis, this quotient decreases over time despite persistently increased apoptosis. Alterations in the expression ratio of these genes may play a role in establishing a new homeostatic set point in the balance between proliferation and apoptosis during the early phase of intestinal adaptation.

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