Evaluation of (99m)technetium-mebrofenin and (99m)technetium-sestamibi as specific probes for hepatic transport protein function in rat and human hepatocytes

Pharm Res. 2010 Sep;27(9):1987-98. doi: 10.1007/s11095-010-0203-x. Epub 2010 Jul 22.


Purpose: This study characterized 99mTc-Mebrofenin (MEB) and 99mTc-Sestamibi (MIBI) hepatic transport and preferential efflux routes (canalicular vs. basolateral) in rat and human sandwich-cultured hepatocytes (SCH).

Methods: 99mTc-MEB and 99mTc-MIBI disposition was determined in suspended hepatocytes and in SCH in the presence and absence of inhibitors and genetic knockdown of breast cancer resistance protein (Bcrp).

Results: The general organic anion transporting polypeptide (Oatp/OATP) inhibitor rifamycin SV reduced initial 99mTc-MEB uptake in rat and human suspended hepatocytes. Initial 99mTc-MIBI uptake in suspended rat hepatocytes was not Na+-dependent or influenced by inhibitors. Multidrug resistance-associated protein (Mrp2/MRP2) inhibitors decreased 99mTc-MEB canalicular efflux in rat and human SCH. 99mTc-MEB efflux in human SCH was predominantly canalicular (45.8 +/- 8.6%) and approximately 3-fold greater than in rat SCH. 99mTc-MIBI canalicular efflux was similar in human and rat SCH; basolateral efflux was 37% greater in human than rat SCH. 99mTc-MIBI cellular accumulation, biliary excretion index and in vitro biliary clearance in rat SCH were unaffected by Bcrp knockdown.

Conclusion: 99mTc-MEB hepatic uptake is predominantly Oatp-mediated with biliary excretion by Mrp2. 99mTc-MIBI appears to passively diffuse into hepatocytes; biliary excretion is mediated by P-gp. The SCH model is useful to investigate factors that may alter the route and/or extent of hepatic basolateral and canalicular efflux of substrates.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily G, Member 2
  • ATP-Binding Cassette Transporters / genetics
  • Aniline Compounds
  • Animals
  • Carrier Proteins / metabolism*
  • Cells, Cultured
  • Female
  • Glycine
  • Hepatocytes / metabolism*
  • Humans
  • Imino Acids / pharmacokinetics*
  • Liver / metabolism*
  • Liver / physiology
  • Male
  • Middle Aged
  • Neoplasm Proteins / genetics
  • Organic Anion Transporters / antagonists & inhibitors
  • Organic Anion Transporters / physiology
  • Organotechnetium Compounds / pharmacokinetics*
  • RNA Interference
  • RNA, Small Interfering / genetics
  • Rats
  • Rats, Wistar
  • Rifamycins / pharmacology
  • Technetium Tc 99m Sestamibi / pharmacokinetics*
  • Tissue Distribution


  • ABCG2 protein, human
  • ATP Binding Cassette Transporter, Subfamily G, Member 2
  • ATP-Binding Cassette Transporters
  • Abcg2 protein, rat
  • Aniline Compounds
  • Carrier Proteins
  • Imino Acids
  • Neoplasm Proteins
  • Organic Anion Transporters
  • Organotechnetium Compounds
  • RNA, Small Interfering
  • Rifamycins
  • Technetium Tc 99m Sestamibi
  • rifamycin SV
  • technetium Tc 99m mebrofenin
  • Glycine