DIRECT DEMOSTRATION OF WATER ABSORPTION IN THE COLON OF INFANTS IN RELATIONSHIP TO CARBOHYDRATE FERMENTATION

Absorption of water from the colon is facilitated by short-chain fatty acids (SCFA). The absorption of water from the colon and its relationship to SCFA production was studied in 5 infants without diarrhea recovering from malnutrition. Total body water was calculated from the 1-h postdose plasma 2H abundance following a 10 mg/kg IV infusion of deuterated water (2H2O). Immediately after the collection of the postdose plasma sample a 4.2 Ml/kg that provided 0.25 g/kg of glucose, 5 mg/kg of 13C-glucose, 40 mmol/L Na Cl, and 100 mg/kg of 2H2O was infused over the next hr through a naso-cecal tube. The increment in 2H plasma abundance 2 hr after the intracecal infusion was used to calculate water absortion from the colon. Breath was analyzed for H2, plasma for acetate, and feces for SCFA, glucose, and 13c-labeled compounds. Results demonstrated that a variation in the different indicators of carbohydrate fermentation (ranges: area-under-the-curve for breath H2 0-945 ppm, plasma acetate 65-2610 umol/L, and increase in fecal acetate 0-1.5 mmol/g) water absorption from the colon was 100%. However, final water content of the feces following the intracecal infusion was 2.6-10.2% greater than in baseline samples. These results indicate that under the conditions of this study initial absorption of water from the colon is carried out with further variable secretion w hich is unrelated to the parameters of fermentation measured.