Holzinger F, Schteingart C D, Ton-Nu H T, Cerrè C, Steinbach J H, Yeh H Z, Hofmann A F
Department of Medicine, University of California, San Diego, La Jolla 92093-0813, USA.
Hepatology. 1998 Aug;28(2):510-20. doi: 10.1002/hep.510280231.
Hepatocyte transport of six fluorescent bile acids containing nitrobenzoxadiazolyl (NBD) or a fluorescein derivative on the side chain was compared with that of natural bile acids using the single-pass perfused rat liver. Compounds were infused at 40 nmol/g liver min for 15 minutes; hepatic uptake and biliary recovery were measured; fractional extraction, intrinsic basolateral clearance, and sequestration (nonrecovery after 45 minutes of additional perfusion) were calculated. Fluorescent bile acids were efficiently extracted during the first 3 minutes (70%-97%), but net extraction decreased with time mostly because of regurgitation into the perfusate. For cholylglycine and ursodeoxycholylglycine (UDC-glycine), extraction was 94% to 99%, and regurgitation did not occur. Intrinsic hepatic clearance of fluorescent bile acids (2-7 mL/g liver x min) was lower than that of cholylglycine (9.0 +/- 0.6; mean +/- SD) and UDC-glycine (21.4 +/- 0.4). Sequestration at 60 minutes was 8% to 26% for fluorescent bile acids with a cholyl moiety (cholylglycylaminofluorescein [CGamF], cholyllysylfluorescein [C-L-F], cholyl-[N epsilon-NBD]-lysine [C-L-NBD], and cholylaminofluorescein [CamF]), 32% for ursodeoxycholylaminofluorescein (UDCamF), and 88% for ursodeoxycholyl-(N epsilon-NBD)lysine (UDC-L-NBD). Cholylglycine and UDC-glycine had <3% retention. Biliary secretion of sequestered UDCamF, but not of UDC-L-NBD, was induced by adding dibutyryl cyclic adenosine monophosphate (DBcAMP) to the perfusate, possibly by translocation to the canaliculus of pericanalicular vesicles containing fluorescent bile acids. Biliary secretion of UDC-L-NBD, but not of UDCamF, was induced by adding cholyltaurine or UDC-taurine, possibly by inhibition of binding to intracellular constituents or of transport into organelles. It is concluded that fluorescent bile acids are efficiently transported across the basolateral membrane, but in contrast to natural conjugated bile acids, are sequestered in the hepatocyte (UDC derivatives > cholyl derivatives). Two modes of hepatic sequestration of fluorescent bile acids were identified. Fluorescent bile acids may be useful to characterize sequestration processes during bile acid transport through the hepatocyte.
利用单通道灌注大鼠肝脏，比较了六种含有硝基苯并恶二唑基（NBD）或侧链上有荧光素衍生物的荧光胆汁酸与天然胆汁酸在肝细胞中的转运情况。化合物以40 nmol/g肝脏·分钟的速度注入15分钟；测量肝脏摄取和胆汁回收情况；计算分数提取率、固有基底外侧清除率和滞留率（额外灌注45分钟后未回收）。荧光胆汁酸在前3分钟内被有效提取（70%-97%），但净提取率随时间下降，主要是因为反流到灌注液中。对于胆酰甘氨酸和熊去氧胆酰甘氨酸（UDC-甘氨酸），提取率为94%至99%，且未发生反流。荧光胆汁酸的固有肝脏清除率（2-7 mL/g肝脏·分钟）低于胆酰甘氨酸（9.0±0.6；平均值±标准差）和UDC-甘氨酸（21.4±0.4）。带有胆酰部分的荧光胆汁酸（胆酰甘氨酰氨基荧光素[CGamF]、胆酰赖氨酰荧光素[C-L-F]、胆酰-[Nε-NBD]-赖氨酸[C-L-NBD]和胆酰氨基荧光素[CamF]）在60分钟时的滞留率为8%至26%，熊去氧胆酰氨基荧光素（UDCamF）为32%，熊去氧胆酰-(Nε-NBD)赖氨酸（UDC-L-NBD）为88%。胆酰甘氨酸和UDC-甘氨酸的滞留率<3%。向灌注液中添加二丁酰环磷酸腺苷（DBcAMP）可诱导滞留的UDCamF的胆汁分泌，但不能诱导UDC-L-NBD的胆汁分泌，这可能是通过含有荧光胆汁酸的胆小管周围囊泡转运到胆小管实现的。添加胆酰牛磺酸或UDC-牛磺酸可诱导UDC-L-NBD的胆汁分泌，但不能诱导UDCamF的胆汁分泌，这可能是通过抑制与细胞内成分的结合或转运到细胞器中实现的。结论是，荧光胆汁酸能有效地穿过基底外侧膜，但与天然结合胆汁酸不同，它们在肝细胞中被滞留（UDC衍生物>胆酰衍生物）。确定了荧光胆汁酸在肝脏中的两种滞留模式。荧光胆汁酸可能有助于表征胆汁酸通过肝细胞转运过程中的滞留过程。
