1. Using a double-lumen tube perfusion system the rates of glycine, glycylglycine, and glycylglycine and glucose absorption from a 30-cm jejunal segment have been studied in vivo in a group of relatively normal Zambian African subjects.
2. To determine the kinetic curve for glycine absorption, four subjects were given consecutive perfusions of 50, 100 and 150 mm-glycine.
3. Six other subjects had consecutive perfusions of (1) a 100 mm-glycine and (2) a 50 mm-glycylglycine solution. Five of the six had a higher absorption rate of glycine from the glycylglycine solution. When data from a further six similar subjects in another study are included, the mean rate of glycine absorption is significantly greater from the glycylglycine compared with the glycine solution (P < 0·001).
4. A further six subjects were given consecutive perfusions of (1) 50 mm-glycylglycine, (2) 50 mm-glycylglycine and 200 mm-glucose, and (3) 200 mm-glucose. The absorption rate of glycine from glycylglycine was lower in all subjects when glucose was present in the perfusing fluid (P < 0·01). Although the mean glucose absorption rate was lower when glycylglycine was present in the perfusing fluid, the difference was not significant.