The effect of amino acids on the intestinal transport of L- and D-xylose in vitro.

1. The intestinal transport of D-xylose by sacs of everted small intestine of the hamster is partially inhibited by L-histidine in concentrations of 5, 10 and 20 mM but not of 2 mM.2. 20 mM concentrations of D-histidine and L-methionine also produce inhibition.3. The inhibition is not due to an alteration in water transport or to a change in pH of the incubating medium.4. The rate of the intestinal transport of L-xylose is about (1/4) of the rate of D-xylose transport and is unaffected by a 20 mM concentration of L-histidine.