The influence of luminal pH on transport of neutral and charged dipeptides by rat small intestine, in vitro

Lister, Norma; Bailey, Patrick D.; Collier, Ian D.; Boyd, C. A. R.; Bronk, J. R.

doi:10.1016/s0005-2736(96)00230-1

Cited by 15 publications

(10 citation statements)

References 13 publications

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“…The transport of VACV and GVACV was found to be pH-dependent (Fig. 8), which is consistent with the report on the interaction of positively charged dipeptides with PEPT1 (Temple et al, 1996;Amasheh et al, 1997;Lister et al, 1997). VACV and GVACV have three pK a values (1.90, 7.47, and 9.43) and exist as a mixture of cationic and neutral species at pH 7.4, which is the pH of maximal transport among the range studied.…”

Section: Discussionsupporting

confidence: 90%

Interactions of the Dipeptide Ester Prodrugs of Acyclovir with the Intestinal Oligopeptide Transporter: Competitive Inhibition of Glycylsarcosine Transport in Human Intestinal Cell Line-Caco-2

Anand¹,

Patel²,

Mitra³

2003

J Pharmacol Exp Ther

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The oligopeptide transporter may be exploited to enhance the absorption of drugs by synthesizing their dipeptide ester prodrugs, which may be recognized as its substrates. Various dipeptide esters of acyclovir (ACV), an antiviral nucleoside analog, were synthesized. Enzymatic hydrolysis and affinity of the prodrugs toward the human intestinal peptide transporter hPEPT1 were studied using the human intestinal Caco-2 cell line. Affinity studies were performed by inhibiting the uptake of [ 3 H]glycylsarcosine by the prodrugs. The uptake of glycylsarcosine was found to be saturable at higher concentrations and was competitively inhibited by the prodrugs of ACV. All prodrugs except Tyr-Gly-ACV demonstrated a higher affinity (1.41-4.96 mM) toward hPEPT1 than cephalexin (8.19 Ϯ 2.12 mM), which was used as a positive control. Two prodrugs, Gly-Val-ACV and Val-Val-ACV, showed comparable affinity to Val-ACV, an amino acid prodrug of ACV recognized by PEPT1/PEPT2. The permeability of Gly-Val-ACV (2.99 Ϯ 0.59 ϫ 10 Ϫ6 cm/s) across Caco-2 was comparable with that of Val-ACV (3.01 Ϯ 0.21 ϫ 10 Ϫ6 cm/s) and was significantly inhibited (63%) in presence of glycylsarcosine. The transport of GVACV across Caco-2 was saturable at higher concentrations, and the parameters were calculated as K m 3.16 Ϯ 0.31 mM and V max 0.014 Ϯ 0.00058 nmol cm Ϫ2 min Ϫ1 . Overall, the results suggest that the dipeptide prodrugs of ACV have a high affinity toward the intestinal oligopeptide transporter hPEPT1 and therefore seem to be promising candidates in the treatment of ocular and oral herpesvirus infections, because cornea and intestinal epithelia seem to express the oligopeptide transporters.

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Section: Discussionsupporting

confidence: 90%

Interactions of the Dipeptide Ester Prodrugs of Acyclovir with the Intestinal Oligopeptide Transporter: Competitive Inhibition of Glycylsarcosine Transport in Human Intestinal Cell Line-Caco-2

Anand¹,

Patel²,

Mitra³

2003

J Pharmacol Exp Ther

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“…Indeed, it was found that a decrease in external pH induces an increase in the rate of transport of negatively charged dipeptide, and to a lesser extent of neutral substrates, while an increasing pH is concomitant with transport of positively charged dipeptides. In vitro observations byLister et al (1997) confirmed these results. They investigated the effect of net charge on the transmembrane transport of hydrolysis-resistant dipeptides (Phe-Ala, Phe-Gln and Phe-Glu) in isolated jejunal loops of rat small intestine and the influence of luminal pH.…”

Section: Structure-functionsupporting

confidence: 67%

“…They investigated the effect of net charge on the transmembrane transport of hydrolysis-resistant dipeptides (Phe-Ala, Phe-Gln and Phe-Glu) in isolated jejunal loops of rat small intestine and the influence of luminal pH. Indeed, transport of neutral and negatively charged dipeptides was stimulated by lowering the luminal pH to 6.8, whereas the contrary was described for positively charged dipeptides (Lister et al, 1997). Tripeptide-like β-lactam antibiotics such as anionic cefixime and zwitterionic cefadroxil were also tested for transport by rabbit PepT1, associated with an additional technique of intracellular pH recording by fluorometric measurements.…”

Section: Structure-functionmentioning

confidence: 99%

Proton-coupled oligopeptide transporter family SLC15: Physiological, pharmacological and pathological implications

Smith

Clémençon

Hediger

2013

Molecular Aspects of Medicine

282

245

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Mammalian members of the proton-coupled oligopeptide transporter family (SLC15) are integral membrane proteins that mediate the cellular uptake of di/tripeptides and peptide-like drugs. The driving force for uphill electrogenic symport is the chemical gradient and membrane potential which favors proton uptake into the cell along with the peptide/mimetic substrate. The peptide transporters are responsible for the absorption and conservation of dietary protein digestion products in the intestine and kidney, respectively, and in maintaining homeostasis of neuropeptides in the brain. They are also responsible for the absorption and disposition of a number of pharmacologically important compounds including some aminocephalosporins, angiotensin-converting enzyme inhibitors, antiviral prodrugs, and others. In this review, we provide updated information on the structure-function of PepT1 (SLC15A1), PepT2 (SLC15A2), PhT1 (SLC15A4) and PhT2 (SLC15A3), and their expression and localization in key tissues. Moreover, mammalian peptide transporters are discussed in regard to pharmacogenomic and regulatory implications on host pharmacology and disease, and as potential targets for drug delivery. Significant emphasis is placed on the evolving role of these peptide transporters as elucidated by studies using genetically modified animals. Whenever possible, the relevance of drug-drug interactions and regulatory mechanisms are evaluated using in vivo studies.

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“…Rat intestinal loops in vitro and vascularly perfused small intestine in situ were used to measure transepithelial fluxes in the intact small intestine as described previously (3,7). Luminal pH was changed using a previously published protocol (8). Isolated murine enterocytes were prepared by enzymatic digestion using haluronidase, and intracellular pH was determined fluorimetrically using carboxy-SNARF (9).…”

Section: Methodsmentioning

confidence: 99%

Peptide Mimics as Substrates for the Intestinal Peptide Transporter

Temple¹,

Stewart²,

Meredith³

et al. 1998

Journal of Biological Chemistry

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4-Aminophenylacetic acid (4-APAA), a peptide mimic lacking a peptide bond, has been shown to interact with a proton-coupled oligopeptide transporter using a number of different experimental approaches. In addition to inhibiting transport of labeled peptides, these studies show that 4-APAA is itself translocated.4-APAA transport across the rat intact intestine was stimulated 18-fold by luminal acidification (to pH 6.8) as determined by high performance liquid chromatography (HPLC); in enterocytes isolated from mouse small intestine the intracellular pH was reduced on application of 4-APAA, as shown fluorimetrically with the pH indicator carboxy-SNARF; 4-APAA trans-stimulated radiolabeled peptide transport in brush-border membrane vesicles isolated from rat renal cortex; and in Xenopus oocytes expressing PepT1, 4-APAA produced trans-stimulation of radiolabeled peptide efflux, and as determined by HPLC, was a substrate for translocation by this transporter.These results with 4-APAA show for the first time that the presence of a peptide bond is not a requirement for rapid translocation through the proton-linked oligopeptide transporter (PepT1). Further investigation will be needed to determine the minimal structural requirements for a molecule to be a substrate for this transporter.The rapid uptake of intact small peptides across the brushborder membrane of the small intestinal epithelium is the major route for absorption of dietary protein ␣-amino nitrogen (1). Hitherto, it has been thought that a number of chemical features, for example free amino and carboxyl termini, are essential in contributing to substrate interaction with, and translocation through, the intestinal peptide transporter.These features include the presence of a peptide bond within the substrate molecules. Indeed a major review (1) states that "it is the presence of peptide bonds which make di-and tripeptide acceptable to the peptide transport systems." Although previous work (e.g. Ref.2) has shown that molecules lacking this feature can inhibit transport of peptides (presumably by substrate binding), we describe here for the first time rapid transport of a small totally non-peptidic substrate through the intestinal peptide transporter. The substrate, 4-aminophenylacetic acid (4-APAA), 1 was selected on the basis of its chemical structure, it being a potential mimic of a dipeptide (D-Phe-LAla) (Fig. 1) which previously we have shown to be an excellent substrate for epithelial peptide transport (3, 4). EXPERIMENTAL PROCEDURESRat renal brush-border membrane vesicles were prepared as described previously (5), and initial rates of labeled peptide transport (influx, efflux) were determined by rapid filtration (4, 6). Rat intestinal loops in vitro and vascularly perfused small intestine in situ were used to measure transepithelial fluxes in the intact small intestine as described previously (3, 7). Luminal pH was changed using a previously published protocol (8). Isolated murine enterocytes were prepared by enzymatic digestion using haluronidase, and i...

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The influence of luminal pH on transport of neutral and charged dipeptides by rat small intestine, in vitro

Cited by 15 publications

References 13 publications

Interactions of the Dipeptide Ester Prodrugs of Acyclovir with the Intestinal Oligopeptide Transporter: Competitive Inhibition of Glycylsarcosine Transport in Human Intestinal Cell Line-Caco-2

Interactions of the Dipeptide Ester Prodrugs of Acyclovir with the Intestinal Oligopeptide Transporter: Competitive Inhibition of Glycylsarcosine Transport in Human Intestinal Cell Line-Caco-2

Proton-coupled oligopeptide transporter family SLC15: Physiological, pharmacological and pathological implications

Peptide Mimics as Substrates for the Intestinal Peptide Transporter

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