Kobayashi Naoko, Tani Takeshi, Hisaka Akihiro, Hara Ken-ichi, Yasumori Toshio
Drug Metabolism, Tsukuba Research Institute, Banyu Pharmaceutical Co., Ltd., 3 Okubo, Tsukuba, Ibaraki 300-2611, Japan.
Pharm Res. 2003 Jan;20(1):89-95. doi: 10.1023/a:1022254910144.
Hepatobiliary excretions of drugs from the blood to the bile include two essential transmembrane processes: uptake into hepatocytes and secretion from hepatocytes. The purpose of this study was to clarify the transport mechanisms underlying these processes for a new non-peptide endothelin antagonist, (+)-(5S,6R,7R)-2-butyl-7-[2((2S)-2-carboxypropyl)-4-methoxyphenyl]-5-(3,4-methylenedioxy-phenyl)cyclopentenol[1,2-b]pyridine-6-carboxylic acid (J-104132).
Biliary excretion of J-104132 was assessed in rats after intravenous injection. To evaluate the hepatic uptake process, J-104132 was incubated with freshly isolated rat hepatocytes and the uptake of J-104132 was calculated. To evaluate the biliary secretion process, the uptake of J-104132 into rat canalicular membrane vesicles that were isolated from normal Sprague-Dawley rats or Eisai hyperbilirubinemic rats was measured.
After intravenous injection, J-104132 was recovered from the bile quantitatively (99.7 +/- 1.3%) as its intact form. J-104132 was taken up by isolated rat hepatocytes in a time- and temperature-dependent manner. The uptake was saturable with Km and Vmax of 5.7 microM and 564 pmol/min/10(6) cells, respectively. The uptake was Na+ independent and was reduced in the presence of ATP depleters (rotenone and carbonyl cyanide-p-(trifluoromethoxy)-phenylhydrazone), organic anions (dibromosulfophthalein, indocyanine green, BQ-123, and pravastatin), and bile acids (taurecholate and cholate). In Sprague-Dawley rats, J-104132 was taken up by canalicular membrane vesicle ATP-dependently with Km and Vmax values of 6.1 microM and 552 pmol/min/mg protein, respectively. However, ATP-dependent uptake disappeared in Eisai hyperbilirubinemic rats.
These data suggest that energy-dependent and carrier-mediated transport systems play important roles in hepatobiliary excretion of J-104132 (both uptake and secretion processes), which is the main excretion route in rats. As for the secretion process of J-104132, an involvement of mrp2 was demonstrated.
药物从血液到胆汁的肝胆排泄包括两个基本的跨膜过程：摄取入肝细胞和从肝细胞分泌。本研究的目的是阐明一种新型非肽内皮素拮抗剂（+）-（5S，6R，7R）-2-丁基-7-[2-（（2S）-2-羧丙基）-4-甲氧基苯基]-5-（3,4-亚甲二氧基苯基）环戊烯醇[1,2-b]吡啶-6-羧酸（J-104132）在这些过程中的转运机制。
静脉注射后在大鼠中评估J-104132的胆汁排泄。为评估肝脏摄取过程，将J-104132与新鲜分离的大鼠肝细胞孵育并计算J-104132的摄取量。为评估胆汁分泌过程，测量J-104132对从正常Sprague-Dawley大鼠或Eisai高胆红素血症大鼠分离的大鼠胆小管膜囊泡的摄取。
静脉注射后，J-104132以完整形式从胆汁中定量回收（99.7±1.3%）。J-104132被分离的大鼠肝细胞以时间和温度依赖性方式摄取。摄取是可饱和的，Km和Vmax分别为5.7μM和564 pmol/min/10⁶细胞。摄取不依赖于Na⁺，并且在存在ATP消耗剂（鱼藤酮和羰基氰化物-p-（三氟甲氧基）-苯基腙）、有机阴离子（二溴磺酞、吲哚菁绿、BQ-123和普伐他汀）以及胆汁酸（牛磺胆酸盐和胆酸盐）时减少。在Sprague-Dawley大鼠中，J-104132被胆小管膜囊泡以ATP依赖性方式摄取，Km和Vmax值分别为6.1μM和552 pmol/min/mg蛋白。然而，在Eisai高胆红素血症大鼠中，ATP依赖性摄取消失。
这些数据表明，能量依赖性和载体介导的转运系统在J-104132的肝胆排泄（摄取和分泌过程）中起重要作用，这是大鼠的主要排泄途径。至于J-104132的分泌过程，已证明mrp2参与其中。
