"Luminal nutrition" versus "functional work-load" as controllers of mucosal morphology and epithelial replacement in the rat small intestine.

Isotonic solutions of substrate were infused into surgically prepared sacs of upper small intestine in conscious unrestrained rats which fed normally via the gut-in-continuity. Infusion of glucose, galactose or sodium chloride all caused a local increase in villus height, while alpha-methyl glucoside and mannose had no effect. Glucose, galactose and alpha-methyl glucoside all stimulated a similar increase in counts of vincristine metaphases in microdissected crypts. although the absolute level of cell production was lower throughout the gut in glucose-infused rats. Sodium chloride infusion also caused a small stimulation of cell production locally, but a considerable increase in the uninfused gut-in-continuity. Mannose infusion had a variable effect on cell production. These results do not support "luminal nutrition" as a controller of epithelial replacement in the rat small intestine, and suggest that a mechanism based on the work-load of the epithelial may be more appropriate.