The effect of amino acids and dipeptides on sodium and water absorption in man.

A perfusion technique has been used to quantitate the effect of the amino acids glycine and alanine and the dipeptides glycyl-glycine and glycyl-L-alanine on sodium and water absorption from the human jejunum. Although no net absorption of sodium and water was seen in the absence of non-electrolytes, a significant stimulation occurred in the presence of both free amino acids and dipeptides. In the case of glycine and alanine, sodium and water absorption increased linearly with increasing concentration of the amino acid and saturation was not demonstrated over the range of concentrations studied. Molar ratios for net absorption of free amino acid and sodium were approximately 1:1 for all but the highest concentration of alanine. In contrast, the corresponding molar ratios for the two dipeptide solutions and sodium were approximately 1:2. Possible explanations for these observations are discussed.