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TARGET CELL ASSAY FOR HUMORAL TROPHIC FACTORS AFTER MABDOMINAL SURGERY

Incorporation of 3H-thymidine(Tdr) into DNA in 3T3 cell culture system is a reproducible assay for growth factor activity. To document existence of circulating factors involved in small intestinal growth after resection, we assayed in this system platelet-free plasma from rats subjected to abdominal surgery, and compared results to changes in intestinal DNA synthesis(S.A.), measured by Tdr incorporation into remaining ileal mucosa. CD rats (20 per group) were studied: C-Unop:controls-no surgery; C-Op:peritoneum incised; R: 80% proximal resection and anastomosis. At 24h and 2 wk, rats were sacrificed lh after intraperitoneal Tdr. RESULTS:CONCLUSIONS: Growth factor activity assayed in the 3T3 cell system increases after both abdominal incision alone and intestinal resection. Simultaneously, DNA S.A. increases dramatically over control levels in remaining ileal mucosa. The production of a trophic effect on the ileum after abdominal incision alone supports the presence of circulating trophic factors. The 3T3 cell assay will be useful in further characterization of humoral factors regulating intestinal adaptation.