REGIONAL EXPRESSION AND DIETARY-REGULATION OF RAT SMALL-INTESTINAL PEPTIDE AND AMINO-ACID TRANSPORTER MESSENGER-RNAS

RT-PCR was used to obtain rat small intestinal cDNAs for two peptide t ransporters, showing conclusively for the first time that both are pre sent in normal intestinal mucosa. Sequencing of these cDNAs showed the m to be highly homologous and similar to two different types of peptid e transport proteins from either colorectal carcinoma cells (Caco-2) o r human and rabbit intestine. An even distribution profile of steady s tate levels of mRNA for both peptide transporters was observed along t he longitudinal axis of small intestine. Both were upregulated in the distal regions of intestine by a high protein diet. Also, high levels of the rat high affinity glutamate transporter EAAC1 were observed in the distal intestine. These results suggest that the distal regions of small intestine play an important role in the absorption of some amin o acids and peptides. Furthermore this area appears to be a primary si te where dietary-induced changes in peptide and amino acid transport o ccurs. (C) 1995 Academic Press, Inc.