[Various features of the initial stages of assimilation of isotope-labelled dipeptide]

Tritium-labeled dipeptide Gly-Leu was administered to noninbred guinea pigs by intracardiac injections, and to Wistar rats--intra-intestinally, through a specially implanted catheter. It was found that after intravenous and intraintestinal administration of isotope-labeled dipeptide the "low-molecular label" was bound by serum proteins. Dissociation of the complexes "low-molecular label"--serum protein in 8 M solution of urea has evidenced a predominantly reversible character of interaction between the low-molecular ligand and protein macromolecule. The results obtained should be taken into consideration during assay of protein absorption from gastro-intestinal tract of laboratory animals.