title: Decreased Mrp2 transport in severe macrovesicular fatty liver grafts.
abstract: BACKGROUND
  Severe macrosteatotic liver has been regarded as a donor contraindication for liver transplantation. However, it has not yet been determined whether hepatocytes lose function before cold ischemia. This study was designed to elucidate certain pathophysiological alterations and how to ameliorate such hepatic dysfunctions.
  
  
  METHODS
  Wistar rats were fed with a choline-deficient diet (CD) for up to 6 wk, and their livers were then perfused with Krebs-Henseleit buffer to examine bile output and biliary constituents. Organic anion transport from hepatocellular canalicular membranes through Mrp2 was examined by kinetic analyses for biliary exclusion of 5-carboxyfluorescein (CF), a fluoroprobe excreted through Mrp2.
  
  
  RESULTS
  Macrovesicular fatty deposits exceeded 60% and serum aspartate aminotransferase (AST) increased on 6-wk CD (CD6w), but not 3-wk CD (CD3w). Mrp2-deficient rat livers (Eisai hyperbilirubinemia) with 3-wk CD were more vulnerable than CD3w livers. In CD6w rats, bile flow rate and biliary glutathione significantly decreased. These declines coincided with the intracellular localization of Mrp2. Moreover, kinetic analyses for biliary CF revealed significant delay in 6-wk CD-fed rat livers. Pioglitazone, a ligand of PPARγ activating protein kinase A (PKA), significantly attenuated this delay by sorting Mrp2 into bile canalicular membranes. However, a PKA inhibitor blunted the increase in CF exclusion, re-localizing Mrp2 into the hepatocellular cytoplasm. A thromboxane A2 synthase inhibitor also ameliorated the CF exclusion delay.
  
  
  CONCLUSIONS
  Pioglitazone activated PKA, increasing Mrp2 transports to detoxify xenobiotics. Pioglitazone may allow the donor indications for liver transplantation to be expanded to include severe macrovesicular fatty livers.
authors.affiliation: Department of Hepatobiliary Pancreatic Surgery, Tokyo Medical and Dental University, Tokyo, Japan. kudomsrg@tmd.ac.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kudo
authors.forename: Daisuke
authors.initials: D
authors.lastname: Ban
authors.forename: Arihiro
authors.initials: A
authors.lastname: Aihara
authors.forename: Takumi
authors.initials: T
authors.lastname: Irie
authors.forename: Takanori
authors.initials: T
authors.lastname: Ochiai
authors.forename: Noriaki
authors.initials: N
authors.lastname: Nakamura
authors.forename: Shinji
authors.initials: S
authors.lastname: Tanaka
authors.forename: Shigeki
authors.initials: S
authors.lastname: Arii
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000502:physiology*; D000818:Animals; D001646:Bile / Q000378:metabolism; D002796:Choline Deficiency / Q000150:complications; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D005234:Fatty Liver / Q000503:physiopathology*; D005978:Glutathione / Q000378:metabolism; D016031:Liver Transplantation / Q000009:adverse effects*; D008297:Male; D047495:PPAR gamma / Q000819:agonists / Q000502:physiology; D000077205:Pioglitazone; D021381:Protein Transport; D051381:Rats; D017208:Rats, Wistar; D045162:Thiazolidinediones / Q000494:pharmacology
chemical_list: D018528:ATP-Binding Cassette Transporters; C423013:Abcc2 protein, rat; D047495:PPAR gamma; D045162:Thiazolidinediones; D017868:Cyclic AMP-Dependent Protein Kinases; D005978:Glutathione; D000077205:Pioglitazone