Characterisation of humoral trophic factors involved in intestinal adaptation using a 3T3 cell growth factor assay.

Indirect evidence has suggested that circulating trophic factor(s) are involved in intestinal adaptation. A 3T3 fibroblast cell culture system was used to more directly delineate the presence of such factors. Rats were divided into four groups; C-unop, those undergoing no surgery, S, those in which a dorsal slit was made; C-op, those in which the peritoneum was incised; and R, those undergoing 80% intestinal resection. At the time of death at 24 hours, one week and two weeks postoperative, stimulation of DNA synthesis in the 3T3 cells was noted after incubation with platelet free plasma from the C-op and R groups, and simultaneously an increase in ileal DNA specific activity occurred. Characterisation of the plasma fraction with growth factor activity revealed it to have a MW of greater than 6,000 and less than 14,000 d. The factor(s) was resistant to reduction with DTT, and was partially inactivated by heating to 60 degrees C. The use of 3T3 cell growth factor assay system allows further characterisation of circulating factors involved in intestinal adaptation.