Nezasa Ken-Ichi, Tian Xianbin, Zamek-Gliszczynski Maciej J, Patel Nita J, Raub Thomas J, Brouwer Kim L R
School of Pharmacy, CB# 7360, Kerr Hall, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7360, USA.
Drug Metab Dispos. 2006 Apr;34(4):718-23. doi: 10.1124/dmd.105.007922. Epub 2006 Jan 24.
This study characterized the hepatobiliary disposition of 5 (and 6)-carboxy-2',7'-dichlorofluorescein (CDF), a model Abcc2/Mrp2 (canalicular) and Abcc3/Mrp3 (basolateral) substrate, in perfused livers from male C57BL/6 wild-type, Abcg2-/-, and Abcc2-/- mice. After single-pass liver perfusion with 1 muM CDF diacetate for 30 min and an additional 30-min perfusion with CDF-free buffer, cumulative biliary excretion of CDF in Abcg2-/- mice was significantly higher than in wild-type mice (65 +/- 6 and 47 +/- 15% of dose, respectively, p < 0.05), whereas CDF recovery in bile of Abcc2-/- mice was negligible. Cumulative recovery of CDF in perfusate was significantly higher in Abcc2-/- (90 +/- 8% of dose) relative to wild-type (35 +/- 11% of dose) mice. Compartmental pharmacokinetic analysis revealed that the rate constant for CDF biliary excretion was significantly increased in Abcg2-/- (0.061 +/- 0.005 min(-1)) compared with wild-type (0.039 +/- 0.011 min(-1)) mice. The rate constant governing the basolateral excretion of CDF was approximately 4-fold higher in Abcc2-/- (0.12 +/- 0.02 min(-1)) relative to wild-type (0.030 +/- 0.011 min(-1)) mice but was not altered in Abcg2-/- (0.031 +/- 0.004 min(-1)) mice. Hepatic Abcc3 protein levels, determined by immunoblot analysis, were approximately 60% higher in Abcc2-/- mice than in wild-type mice. In contrast, neither Abcc3 protein levels nor Abcc2 mRNA levels were altered in Abcg2-/- relative to wild-type mice. These data in knockout mouse models demonstrate that loss of expression and function of one canalicular transport protein may change the route and/or extent of excretion into bile or perfusate because of alterations in the function of other basolateral or canalicular transport proteins.
本研究对5（和6）-羧基-2'，7'-二氯荧光素（CDF）在雄性C57BL/6野生型、Abcg2-/-和Abcc2-/-小鼠灌注肝脏中的肝胆处置进行了表征，CDF是一种Abcc2/Mrp2（胆小管）和Abcc3/Mrp3（基底外侧）的模型底物。在用1μM CDF二乙酸盐进行单次肝脏灌注30分钟并随后用不含CDF的缓冲液再灌注30分钟后，Abcg2-/-小鼠中CDF的累积胆汁排泄量显著高于野生型小鼠（分别为剂量的65±6%和47±15%，p<0.05），而Abcc2-/-小鼠胆汁中的CDF回收率可忽略不计。相对于野生型小鼠（剂量的35±11%），Abcc2-/-小鼠灌注液中CDF的累积回收率显著更高（剂量的90±8%）。房室药代动力学分析显示，与野生型小鼠（0.039±0.011 min-1）相比，Abcg2-/-小鼠（0.061±0.005 min-1）中CDF胆汁排泄的速率常数显著增加。相对于野生型小鼠（0.030±0.011 min-1），Abcc2-/-小鼠（0.12±0.02 min-1）中控制CDF基底外侧排泄的速率常数约高4倍，但在Abcg2-/-小鼠（0.031±0.004 min-1）中未改变。通过免疫印迹分析测定，Abcc2-/-小鼠肝脏中的Abcc3蛋白水平比野生型小鼠高约60%。相比之下，相对于野生型小鼠，Abcg2-/-小鼠中的Abcc3蛋白水平和Abcc2 mRNA水平均未改变。敲除小鼠模型中的这些数据表明，一种胆小管转运蛋白表达和功能的丧失可能会由于其他基底外侧或胆小管转运蛋白功能的改变而改变胆汁或灌注液中排泄的途径和/或程度。
