Kiyomi Hayashi

The Predominant Contribution of Oligopeptide Transporter PepT1 to Intestinal Absorption of β‐Lactam Antibiotics in the Rat Small Intestine

Although recent evidence suggests that certain β‐lactam antibiotics are absorbed via a specific transport mechanism, its nature is unclear. To confirm whether peptide transport in the rat can be largely ascribed to the intestinal oligopeptide transporter PepT1, the transporter has been functionally characterized and its significance in the intestinal absorption of β‐lactam antibiotics was evaluated.

Immunolocalization and pharmacological relevance of oligopeptide transporter PepT1 in intestinal absorption of β-lactam antibiotics

A polyclonal antibody (anti‐PepT1/C) was raised against the rabbit intestinal H+‐coupled oligopeptide transporter, PepT1. Anti‐PepT1/C detected 70–80‐kDa protein in crude membranes obtained from rabbit duodenum, jejunum and ileum. PepT1 was localized in the brush‐border of the absorptive epithelial cells by subcellular fractionation of membranes on a sucrose density gradient and by immunohistochemistry using light and electron microscopy. Transport activity for cephalosporins and dipeptide expressed in Xenopus laevis oocytes injected with total mRNA obtained from rabbit small intestine was eliminated completely by prehybridization of the mRNA with antisense oligonucleotide against the 5′‐coding region of rabbit PepT1 cDNA.