In vivo visualization and quantification of (Disturbed) Oatp-mediated hepatic uptake and Mrp2-mediated biliary excretion of 99mTc-mebrofenin in mice

J Nucl Med. 2013 Apr;54(4):624-30. doi: 10.2967/jnumed.112.108233. Epub 2013 Feb 25.

Abstract

Hepatic transport of (99m)Tc-mebrofenin through organic anion transport protein 1a and 1b (Oatp1a/1b) and multidrug resistance protein 2 (Mrp2) was investigated by small-animal SPECT. On the basis of the results, a noninvasive method to visualize and quantify disturbances in hepatic transport is proposed.

Methods: Friend virus B wild-type mice (untreated, bile duct-ligated, vehicle- or rifampicin-treated) and strain-matched knockout mice unable to express the uptake transporters Oatp1a/1b (Slco1a/1b(-/-)/(-/-)) or the efflux transporter Mrp2 (Abcc2(-/-)) were intravenously injected with (99m)Tc-mebrofenin (n = 3 per group). After dynamic small-animal SPECT and short CT acquisitions, time-activity curves of the liver and of the gallbladder and intestines were obtained and correlated with direct blood samples.

Results: Normal hepatobiliary clearance of (99m)Tc-mebrofenin was severely impaired in the bile duct-ligated animal, as evidenced by elevated hepatic tracer levels. In Slco1a/1b(-/-)/(-/-) mice, a lower area under the curve (AUC) for the liver (P = 0.014) was obtained and no activity was detected in the gallbladder and intestines. Renal rerouting was observed, along with an increase in the blood AUC (P = 0.01). Abcc2(-/-) mice had a higher liver AUC (P = 0.009), a delayed emergence time of (99m)Tc-mebrofenin in the gallbladder (P = 0.009), and a lower AUC for the gallbladder and intestines (P = 0.001). The blood curve was similar to that of wild-type mice. (99m)Tc-mebrofenin disposition was altered after rifampicin treatments. We observed a dose-dependent delayed time point at which tracer maximized in liver, an increased AUC for liver, and a lower AUC for gallbladder and intestines (P = 0.042, 0.034, and 0.001, respectively, highest dose). Emergence in the gallbladder occurred later (P = 0.009, highest dose), and blood AUC was higher (P = 0.006).

Conclusion: The current study visualized and quantified hepatic uptake and biliary efflux of (99m)Tc-mebrofenin. Our results demonstrated the possibility of discriminating, on a quantitative level, between lack of functional activity of sinusoidal uptake versus that of biliary efflux transporters.

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B / metabolism*
  • Animals
  • Bile Ducts / drug effects
  • Bile Ducts / metabolism*
  • Bile Ducts / surgery
  • Biological Transport / drug effects
  • CHO Cells
  • Cricetinae
  • Cricetulus
  • Dose-Response Relationship, Drug
  • Female
  • Imino Acids / metabolism*
  • Ligation
  • Liver / diagnostic imaging
  • Liver / drug effects
  • Liver / metabolism*
  • Mice
  • Organic Anion Transport Protein 1 / metabolism*
  • Organic Anion Transporters, Sodium-Independent / metabolism*
  • Organic Cation Transporter 1 / metabolism
  • Organotechnetium Compounds / metabolism*
  • Rifampin / pharmacology
  • Tomography, Emission-Computed, Single-Photon*

Substances

  • ATP Binding Cassette Transporter, Subfamily B
  • Imino Acids
  • Organic Anion Transport Protein 1
  • Organic Anion Transporters, Sodium-Independent
  • Organic Cation Transporter 1
  • Organotechnetium Compounds
  • P-glycoprotein 2
  • Slc22a7 protein, mouse
  • technetium Tc 99m mebrofenin
  • Rifampin