Transport of low and high molecular peptides across rabbit Peyer's patches

The permeability of peptides across rabbit jejunal epithelium (JE) and Peyer's patches (PP) was compared. Kyotorphin (L-tyrosyl-L-arginine) was almost completely hydrolyzed during its membrane transport in both PP and JE, but [D-Arg2]Kyotorphin (L-tyrosyl-D-arginine) was less hydrolyzed in PP than in JE. Since the permeability of intact [D-Arg2]Kyotorphin was almost equal in PP and JE, no superiority of PP to JE was found for dipeptide transport. More intact fluorescein isothiocyanate (FITC)-labeled bovine serum albumin (FITC-BSA) and concanavalin A (FITC-Con A) were transported in PP than in JE. At both absorption sites, the transport of the intact FITC-Con A was superior to that of the intact FITC-BSA. Colchicine significantly reduced the total transport of the intact and degradation forms of both peptides and the reduction ratio was greater in PP than in JE. Accordingly, it was suggested that PP can be used as prominent absorption sites for polypeptides since they have lower peptidase activity and higher endocytosis activity than JE.