TY - JOUR
T1 - Basolateral glycylsarcosine (Gly-Sar) transport in Caco-2 cell monolayers is pH dependent
AU - Berthelsen, Ragna
AU - Nielsen, Carsten Uhd
AU - Brodin, Birger
N1 - © 2013 Royal Pharmaceutical Society.
PY - 2013/7
Y1 - 2013/7
N2 - Objectives: Transepithelial di/tripeptide transport in enterocytes occurs via the apical proton-coupled peptide transporter, hPEPT1 (SLC15A1) and a basolateral peptide transporter, which has only been characterized functionally. In this study we examined the pH dependency, substrate uptake kinetics and substrate specificity of the transporter. Methods: We studied the uptake of [14C]Gly-Sar from basolateral solution into Caco-2 cell monolayers grown for 17-22 days on permeable supports, at a range of basolateral pH values. Key findings: Basolateral Gly-Sar uptake was pH dependent, with a maximal uptake rate at a basolateral pH of 5.5. Uptake of Gly-Sar decreased in the presence of the protonophore nigericin, indicating that the uptake was proton-coupled. The uptake was saturable, with a maximal flux (Vmax) of 408 ± 71, 307 ± 25 and 188 ± 19 pmol/cm2/min (mean ± S.E., n = 3) at basolateral pH 5.0, 6.0 and 7.4, respectively. The compounds Gly-Asp, Glu-Phe-Tyr, Gly-Glu-Gly, Gly-Phe-Gly, lidocaine and, to a smaller degree, para-aminohippuric acid were all shown to inhibit the basolateral uptake of Gly-Sar. Conclusions: The study showed that basolateral Gly-Sar transport in the intestinal cell line Caco-2 is proton-coupled. The inhibitor profile indicated that the transporter has broad substrate specificity.
AB - Objectives: Transepithelial di/tripeptide transport in enterocytes occurs via the apical proton-coupled peptide transporter, hPEPT1 (SLC15A1) and a basolateral peptide transporter, which has only been characterized functionally. In this study we examined the pH dependency, substrate uptake kinetics and substrate specificity of the transporter. Methods: We studied the uptake of [14C]Gly-Sar from basolateral solution into Caco-2 cell monolayers grown for 17-22 days on permeable supports, at a range of basolateral pH values. Key findings: Basolateral Gly-Sar uptake was pH dependent, with a maximal uptake rate at a basolateral pH of 5.5. Uptake of Gly-Sar decreased in the presence of the protonophore nigericin, indicating that the uptake was proton-coupled. The uptake was saturable, with a maximal flux (Vmax) of 408 ± 71, 307 ± 25 and 188 ± 19 pmol/cm2/min (mean ± S.E., n = 3) at basolateral pH 5.0, 6.0 and 7.4, respectively. The compounds Gly-Asp, Glu-Phe-Tyr, Gly-Glu-Gly, Gly-Phe-Gly, lidocaine and, to a smaller degree, para-aminohippuric acid were all shown to inhibit the basolateral uptake of Gly-Sar. Conclusions: The study showed that basolateral Gly-Sar transport in the intestinal cell line Caco-2 is proton-coupled. The inhibitor profile indicated that the transporter has broad substrate specificity.
U2 - 10.1111/jphp.12061
DO - 10.1111/jphp.12061
M3 - Journal article
C2 - 23738724
SN - 0022-3573
VL - 65
SP - 970
EP - 979
JO - Journal of Pharmacy and Pharmacology
JF - Journal of Pharmacy and Pharmacology
IS - 7
ER -