Contribution of organic anion transporting polypeptide OATP-C to hepatic elimination of the opioid pentapeptide analogue [D-Ala2, D-Leu5]-enkephalin

J Pharm Pharmacol. 2003 Jul;55(7):1013-20. doi: 10.1211/0022357021440.


The objective of this study was to examine the transport activity of the human organic anion transporter OATP-C (SLC21A6) for oligopeptides that are eliminated rapidly from the systemic circulation. We focused on an opioid peptide analogue, [D-Ala(2), D-Leu(5)]-enkephalin (DADLE), a linear pentapeptide modified to be stable. [(3)H]DADLE was taken up by rat isolated hepatocytes in a saturable manner and highly accumulated in the liver after intravenous administration to rats. The uptake of [(3)H]DADLE by the isolated hepatocytes was inhibited by several organic anions and pentapeptides, but not by tetra- or tripeptides. When OATP-C was expressed in Xenopus laevis oocytes, a significant increase in uptake of [(3)H]DADLE was observed. Moreover, the inhibitory effects of various compounds, including some peptides, on [(3)H]estrone-3-sulfate uptake by OATP-C were similar to those observed in [(3)H]DADLE uptake by rat isolated hepatocytes. In conclusion, it was demonstrated that OATP-C contributes to the rapid hepatic excretion of peptides and peptide-mimetic drugs.

MeSH terms

  • Animals
  • Anions
  • Bile
  • Biological Transport
  • Enkephalin, D-Penicillamine (2,5)- / pharmacokinetics
  • Enkephalin, Leucine-2-Alanine / pharmacokinetics*
  • Estrone / analogs & derivatives*
  • Estrone / pharmacokinetics
  • Hepatocytes / metabolism*
  • In Vitro Techniques
  • Injections, Intravenous
  • Liver-Specific Organic Anion Transporter 1 / metabolism*
  • Oocytes / metabolism
  • Peptides / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Structure-Activity Relationship
  • Xenopus laevis


  • Anions
  • Liver-Specific Organic Anion Transporter 1
  • Peptides
  • Estrone
  • Enkephalin, Leucine-2-Alanine
  • Enkephalin, D-Penicillamine (2,5)-
  • estrone sulfate