Hydrogen gas excretion after sucrose gavage in the fasted rat

The effect of a 3-day fast on the functional ability of the adult rat to hydrolyze and absorb sucrose was determined. The evaluation was based on previous studies which have shown the total amount of hydrogen gas (H2) excreted by the animal to reflect the extent of undigested carbohydrate entering the colon from the small intestine. H2 excretion was measured using a gas chromatographic technique in experimental (72 h fasted) and control (12 h fasted) animals after administration of sucrose by gastric gavage. Total H2 excretion was 3-fold higher in the experimental animals (n = 5) than in the controls (n = 5) (p less than 0.005) indicating a significant increase of sucrose malabsorption in the experimental animals. Administration of a second dose of sucrose 8 to 9 h after the first dose (refeeding) resulted in markedly decreased malabsorption relative to the first administration in both experimental (n = 2) and control (n = 2) animals. These results suggest that a 3-day fast markedly impairs the ability of the intestine to hydrolyze and absorb sucrose and that refeeding rapidly restores the ability to utilize this substrate. H2 excretion was similar between experimental and control animals after the administration of lactulose, a nonabsorbed and nondigested carbohydrate, suggesting that the observed results of the sucrose studies were independent of any possible changes in the intestinal microflora.