Effect of sodium ion coupled nutrient transport on intestinal permeability in chronically catheterised rats.

BACKGROUND The significance of Nanutrient cotransport induced alterations in paracellular permeability is controversial. Most previous studies have measured intestinal permeability using in vitro methods or in vivo methods immediately after surgical bowel manipulation, and therefore may not be applicable to normal physiological conditions. AIMS To determine whether activation of Na coupled nutrient transport increases intestinal permeability under normal physiological conditions. METHODS The effect of Na-nutrient cotransport on intestinal permeability was measured in unrestrained, unanaesthetised, chronically catheterised male Sprague-Dawley rats using two different methods: measurement of the rate of absorption of passively absorbed hexoses, mannitol and L-glucose; and measurement of the mannitol:urea diffusion ratio. RESULTS L-Glucose and mannitol absorption were not increased in the presence of D-glucose, alanine, maltose, or peptides. The mannitol:urea diffusion ratio was not increased by the presence of D-glucose. The presence of D-glucose in the intestinal lumen for 20 minutes did not alter intestinal permeability. CONCLUSIONS Under normal physiological conditions, Na coupled nutrient transport does not increase intestinal permeability.