Effect of dietary fiber and carcinogen on metabolism in isolated colonocytes during tumorigenesis

Fermentation of dietary fiber in the colon results in production of short chain fatty acids (SCFA), especially butyrate. Although butyrate is known to be the preferred energy source for normal colonocytes, its fate during the transformation process has not been reported. The effects of the dietary fibers (cellulose and pectin) on the metabolism of colonocytes during experimental carcinogenesis (colonocytes were harvested after 6, 16 and 36 weeks after carcinogen injection) were examined in rats. At 6 wks there were no significant differences in energy metabolism among treatments. In contrast, at 16 wks, carcinogen (AOM)-injected rats had a lower rate of CO;Production of CO;Production of citrulline, ornithine, arginine and urea from glutamine were detected after incubation. Concentrations of citrulline, ornithine and arginine in the colonocytes from pectin-fed rats were lower than from cellulose-fed. The results suggest the presence of the urea cycle in rat colonocytes. In addition, intermediates of the urea cycle are affected by type of fiber in the diet.