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Impaired biliary excretion of organic anions and cations in bile duct-ligated rat
International
ELSEVIER
Hepatology Communications 5 (1996) 201-206
Impaired biliary excretion of organic anions and cations in bile duct-ligated rat Hajime Takikawa *, Naoyo Sano, Satoko Fukumura, Satoko Uegaki, Masami Yamanaka Department
of Medicine,
Teikyo
University
School of Medicine, Japan
Kaga
2-1 l-1,
Itabashi-ku,
Tokyo
173,
Received 25 March 1996; revised 25 April 1996; accepted IO May 1996
Abstract The effects of bile duct ligation for 3 days on biliary excretion of organic anions and cations were studied in the rat. Biliary excretion of organic anions, sulfobromophthalein, leukotriene C, and pravastatin, was markedly impaired. Biliary excretion of organic cations, vinblastine and erythromycin was also markedly impaired. These findings indicate that, in the bile duct-ligated rats, various excretory pathways from the liver are damaged, at least partly due to the impairment of canalicular carriers. Keywords:
Obstructive
jaundice;
Organic
anions; Organic
cations; Bile duct ligation;
Biliary
excretion
1. Introduction Biliary excretion of bile acids [l-3] and organic anions [4-61 has been reported to be mediated by distinct ATP-dependent carriers at the canalicular membrane. Furthermore, cationic anti-cancer drugs are reported to be excreted into bile by a P-glycoprotein (P-GP) which is encoded by a multidrug resistance (MDR) 1 gene [7-91. In patients with obstructive jaundice, bile acid metabolism changes due to the impairment of the enterohepatic circulation of bile acids. We previously reported * Corresponding author. Tel.: + 81 3 3964 1211: fax: + 81 3 3964 5710. 0928-4346/96/$12.00 0 1996 Elsevier Science Ireland Ltd. All rights reserved PII
SO928-4346(96)00299-X
202
H. Takikawa
et al. )/)Interrtationul
Heputology
Cor,zrlttotic,crtions
5 (1996)
201-206
that biliary excretion of bile acids and glutathione, which are important for the canalicular bile formation [ 10,111, was impaired in the bile duct-ligated rats [12]. Here we studied the biliary excretion of organic anions, sulfobromophthalein (BSP), leukotriene C, (LTC,) and pravastatin (PS), an HMG CoA reductase inhibitor, and organic cations, vinblastine (VLB), a P-GP substrate, and erythromycin (EM) in the bile duct-ligated rats.
2. Materials
and methods
2.1. Materials
BSP was purchased from Dai-ichi Pharmaceutical Co. (Tokyo). [3H]LTC, (173 Ci/mmol) was obtained from Du Pont Co. (Wilmington, DE), [3H]VLB (11.2 Ci/mmol) was from Amersham International plc (Buckinghamshire, UK), and [14C]EM (55 mCi/mmol) was from American Radiolabeled Chemicals Inc. (St. Louis, MO). [i4C]PS (10 mCi/mmol) was kindly supplied by Sankyo Pharmaceutical Co. (Tokyo). The other reagents were of analytical grade. 2.2. Experimental
procedures
Male Sprague-Dawley rats (250 g) were anesthetized with an intraperitoneal injection of pentobarbital (5 mg/lOO g body wt), the common bile duct was ligated at two portions, and the abdomen was closed. Untreated rats were used as controls. Three days after, under pentobarbital anesthesia after overnight fasting, the common bile duct was cannulated with a PE-10 tube (Becton Dickinson Primary Care Diagnostics, Franklin Lake, NJ). The femoral vein was cannulated with a 3-Fr venous catheter, and 3% human albumin in a 5% glucose solution (standard solution) was infused at the rate of 2 ml/h during the experiment. The animals were placed in restrictive cages and their body temperature was maintained at 37°C during the experiments. Thirty minutes after bile duct cannulation, BSP (1 pmol/lOO g body wt.), and tracer doses of [3H]LTC, and [14C]EM, or [3H]VLB and [‘4C]PS dissolved in the standard solution (50 ~1) was intravenously injected via the femoral vein. Bile samples were collected every 10 or 15 min for 60 or 90 min and measured for BSP concentration by OD,xo or the radioactivity of 3H and 14C. Data were expressed as means f S.D. Biliary excretion was shown by nmol/ min/lOO g body wt for BSP, and percentage of the total administered dose/l5 min for radiolabeled materials. Although the dead space of the bile duct may have increased in the bile duct-ligated rats, the time delay of bile sampling is considered to have only a minor effect on the results. Statistical analysis was performed by Mann-Whitney’s U-test using a StatView-J 4.02, and P -C 0.05 was considered to indicate significance of differences.
H. Takikawil
et al. / International
Hepatology
Communications
5 (1996)
201-206
203
3. Results Bile flow was increased in the bile duct-ligated rats at the time of the injection of organic anions and gradually decreased with the decrease of the bile acid pool as reported previously [12] (Figs. l-3). Biliary excretion of BSP was markedly delayed in the bile-duct ligated rats (Fig. 1). Biliary excretion of a tracer amount of [3H]lTC, was markedly delayed in the bile ductligated rats (Fig. 2); biliary excretion during 90 min was 67.9 f 9.5% and 15.8 f 6.8% of the administered dose in the control and bile duct-ligated rats, respectively (P < 0.05). Biliary excretion of a tracer dose of [r4C]EM was also markedly delayed in the bile duct-ligated rats (Fig. 2); biliary excretion during 90 min was 35.6 + 9.7% and 9.2 + 4.7% of the administered dose in the control and bile duct-ligated rats, respectively (P < 0.05). Biliary excretion of a tracer amount of [3H]VLB was delayed in the bile duct-ligated rats (Fig. 3); biliary excretion during 60 min was 13.9 & 1.8% and 3.9 _+ 1.3% of the administered dose in the control and bile duct-ligated rats, respectively (P < 0.05). Biliary excretion of a tracer dose of [‘4C]PS was markedly delayed in the bile duct-ligated rats (Fig. 3); biliary excretion during 60 min was 82.8 + 6.3% and 10.3 f 3.0% of the administered dose in the control and bile duct-ligated rats, respectively (P < 0.05).
0
0
60
30
Time
90
(min)
Fig. 1. Biliary excretion of BSP. BSP (1 pmol/lOO g b. wt.) was intravenously administered rats (n = 4, open circles) and bile duct-ligated rats for 3 days (n = 3, closed circles). Values * S.D.
to control are means
204
H. Takikawa
et al. / International
0’
Hepatohgy Communications
5 (1996)
0
30
60
90
0
30
60
90
0
30
60
90
201-206
30
Time (min) Fig. 2. Biliary excretion of 13H]LTC, and [%]EM. Tracer doses of radiolabeled materials were intravenously administered to control rats (n = 4, open circles) and bile duct-ligated rats for 3 days (n = 3, closed circles). Values are means f SD.
4. Discussion
In the bile duct-ligated rats, although biliary excretion of taurocholate was only slightly impaired, its transport maximum was markedly decreased [12]. Furthermore, biliary glutathione excretion was markedly impaired in the bile duct-ligated rats [12]. Biliary excretion of lithocholate-3-0-glucuronide, the excretory pathway of which was considered to be the same as that of organic anions in the studies with mutant hyperbilirubinemic rats [ 13,141, was also markedly impaired. The biliary excretion of BSP and LTC, was also markedly impaired in the bile duct-ligated rats. The impaired biliary excretion of these organic anions may be due to the damage of the ATP-dependent canalicular transporter as suggested by the study with canalicular membrane vesicles of rats with ethinylestradiol-induced cholestasis
[151.
In contrast, the multiplicity of biliary excretion of organic anions has been suggested [16- 181 and biliary excretion of PS, the excretory pathway of which is considered to be distinct from that for BSP and LTC, (Y. Adachi et al. and Y. Sugiyama et al., personal communications), was also markedly impaired in the bile
H. Takikawa
et al. / International
Hepatology
Communications
5 (1994)
201-206
205
duct-ligated rats. These findings suggest that multiple damage of canalicular organic anion carriers occurred in the bile duct-ligated rats, and may also explain the presence of obstructive jaundice patients with consistently high serum bilirubin levels despite of the appropriate bile flow and biliary bile acid excretion after bile drainage. Schrenk et al. reported that the expression of MDR 1 was increased in bile duct-ligated rats [19]. However, the present data showed impaired biliary excretion of VLB in the bile duct-ligated rats. These findings suggest either the involvement of the other excretory pathway for VLB and its damage, or the damage of hepatic uptake or intrahepatic transport of VLB. The multiplicity of canalicular transport of organic cations has recently been reported [20]. The mechanism of biliary EM excretion is poorly understood, and that involved in the marked impairment of EM excretion in the bile duct-ligated rats is unknown. However, a canalicular carrier for organic cations may also be damaged as is that for organic anion.
lp-
0’
.....b .........b .........~ ........~,............ *
30
60
0
30
60
0
30
60
0
4r
Time (min) Fig. 3. Biliary excretion of [3H]VLB and [‘4C]PS. Tracer doses of radiolabeled materials were intravenously administered to control rats (n = 4, open circles) and bile duct-ligated rats for 3 days (n = 6, closed circles). Values are means + S.D.
206
H. Tukikawu
et al. / b~ternatior~al
Hrpatology
Communications
5 (1996)
Xl-206
References [l] Adachi Y. Kobayashi H, Kurumi Y, Shouji M, Kitano M, Yamamoto T. ATP-dependent taurocholate transport by rat liver canalicular membrane vesicles. Hepatology 1991; 14: 6555659. [2] Nishida T. Gatmaitan Z, Che M. Arias IM. Rat liver canalicular membrane vesicles contain an ATP-dependent bile acid transport system. Proc Nat1 Acad Sci USA 1991: 88: 6590-6594. [3] Miiller M, Ishikawa T, Berger U et al. ATP-dependent transport of taurocholate across the hepatocyte canalicular membrane mediated by a 1IO-kDa glycoprotein binding ATP and bile salt. J Biol Chem 1991; 266: 18920-18926. [4] Kitamura T, Jansen P, Hardenbrook C, Kamimoto U, Gatmaitan Z, Arias IM. Defective ATP-dependent canalicular transport of organic anions in mutant (TR-) rats with conjugated hyperbilirubinemia. Proc Nat1 Acad Sci USA 1990; 87: 355773561. [S] Kobayashi K, Sogame Y, Hara H, Hayashi K. Mechanism of glutathione S-conjugate transport in canalicular and basolateral rat liver plasma membranes. J Biol Chem 1990; 265: 773777741. [6] Ishikawa T, Mtiller M, Khinemann C. Schaub T, Keppler D. ATP-dependent primary active transport of cysteinyl leukotrienes across liver canalicular membrane. Role of the ATP-dependent transport system for glutathione conjugates. J Biol Chem 1990: 265: 19279919286. [7] Kamimoto Y, Gatmaitan Z, Hsu J, Arias IM. The function of gp 170, the multidrug resistance gene product, in rat liver canalicular membrane vesicles. J Biol Chem 1989; 264: 11693311698. [8] Watanabe T, Miyauchi S, Sawada Y. et al. Kinetic analysis of hepatobiliary transport of vincristine in perfused rat liver. Possible roles of P-glycoprotein in biliary excretion of vincristine. J Hepatol 1992; 16: 77-88. [9] Mtiller M, Mayer R, Hero U, Keppler D. ATP-dependent transport of amphophilic cations across the hepatocyte canalicular membrane mediated by mdr 1 P-glycoprotein. FEBS Lett 1994; 343: 1688172. [IO] Erlinger S. Secretion of Bile. In: Schiff L, Schiff ER, eds. Diseases of the Liver, 7th edn. Philadelphia, PA: Lippincott, 1993: 85-107. [ll] Ballatori N, Truong AT. Glutathione as primary osmotic driving force in hepatic bile formation. Am J Physiol 1992; 263: G617-G624. [I21 Takikawa H, Wako Y, Sano N, Yamanaka M. Changes in biliary excretory mechanisms in bile duct-ligated rat. Dig Dis Sci 1996; 41: 256-262. [13] Kuipers F, Radominska A, Zimniak P, et al. Defective biliary secretion of bile acid 3-O-glucuronides in rats with hereditary hyperbilirubinemia. J Lipid Res 1989; 30: 1835- 1845. [14] Takikawa H, Sano N, Narita T et al. Biliary excretion of bile acid conjugates in a hyperbilirubinemic mutant Sprague-Dawley rats. Hepatology 1991; 14: 352-360. [15] Bossard R, Stieger B. O’Neill B, Fricker G, Meier PJ. Ethinylestradiol treatment induces multiple canalicular membrane transport alterations in rat liver. J Clin Invest 1992; 263: G617-G624. [16] Sathrakul K, Suzuki H, Yamada T. Hanano M, Sugiyama Y. Multiple transport systems for organic anions across the bile canalicular membrane. J Pharmacol Exp Ther 1992; 268: 6573. [17] Takikawa H, Nishikawa K, Sano N. Yamanaka M, Horie T. Mechanisms of biliary excretion of lithocholate-3-sulfate in Eisai hyperbilirubinemic rats (EHBR). Dig Dis Sci 1995; 40: 1792-1797. [18] Takenaka 0, Horie T, Kobayashi K. Suzuki H, Sugiyama Y. Kinetic analysis of hepatobiliary transport for conjugated metabolites in the perfused liver of mutant rats (EHBR) with hereditary conjugated hyperbilirubinemia. Pharm Res 1995; 12: 1746- 1755. [19] Schrenk D, Gant TW, Presiegger K-H, Silverman JA, Marino PA, Thorgeirson SS. Induction of multidrug resistance gene expression during cholestasis in rats and non-human primates, Hepatology 1993; 17: 8544860. [20] Smit H. Dubin E, Steen H, Roggeveld J, Oosting R. Meijer DKF. Multiple carriers involved in the biliary excretion of cationic drugs. Hepatology 1995; 22: 309A.
ELSEVIER
Hepatology Communications 5 (1996) 201-206
Impaired biliary excretion of organic anions and cations in bile duct-ligated rat Hajime Takikawa *, Naoyo Sano, Satoko Fukumura, Satoko Uegaki, Masami Yamanaka Department
of Medicine,
Teikyo
University
School of Medicine, Japan
Kaga
2-1 l-1,
Itabashi-ku,
Tokyo
173,
Received 25 March 1996; revised 25 April 1996; accepted IO May 1996
Abstract The effects of bile duct ligation for 3 days on biliary excretion of organic anions and cations were studied in the rat. Biliary excretion of organic anions, sulfobromophthalein, leukotriene C, and pravastatin, was markedly impaired. Biliary excretion of organic cations, vinblastine and erythromycin was also markedly impaired. These findings indicate that, in the bile duct-ligated rats, various excretory pathways from the liver are damaged, at least partly due to the impairment of canalicular carriers. Keywords:
Obstructive
jaundice;
Organic
anions; Organic
cations; Bile duct ligation;
Biliary
excretion
1. Introduction Biliary excretion of bile acids [l-3] and organic anions [4-61 has been reported to be mediated by distinct ATP-dependent carriers at the canalicular membrane. Furthermore, cationic anti-cancer drugs are reported to be excreted into bile by a P-glycoprotein (P-GP) which is encoded by a multidrug resistance (MDR) 1 gene [7-91. In patients with obstructive jaundice, bile acid metabolism changes due to the impairment of the enterohepatic circulation of bile acids. We previously reported * Corresponding author. Tel.: + 81 3 3964 1211: fax: + 81 3 3964 5710. 0928-4346/96/$12.00 0 1996 Elsevier Science Ireland Ltd. All rights reserved PII
SO928-4346(96)00299-X
202
H. Takikawa
et al. )/)Interrtationul
Heputology
Cor,zrlttotic,crtions
5 (1996)
201-206
that biliary excretion of bile acids and glutathione, which are important for the canalicular bile formation [ 10,111, was impaired in the bile duct-ligated rats [12]. Here we studied the biliary excretion of organic anions, sulfobromophthalein (BSP), leukotriene C, (LTC,) and pravastatin (PS), an HMG CoA reductase inhibitor, and organic cations, vinblastine (VLB), a P-GP substrate, and erythromycin (EM) in the bile duct-ligated rats.
2. Materials
and methods
2.1. Materials
BSP was purchased from Dai-ichi Pharmaceutical Co. (Tokyo). [3H]LTC, (173 Ci/mmol) was obtained from Du Pont Co. (Wilmington, DE), [3H]VLB (11.2 Ci/mmol) was from Amersham International plc (Buckinghamshire, UK), and [14C]EM (55 mCi/mmol) was from American Radiolabeled Chemicals Inc. (St. Louis, MO). [i4C]PS (10 mCi/mmol) was kindly supplied by Sankyo Pharmaceutical Co. (Tokyo). The other reagents were of analytical grade. 2.2. Experimental
procedures
Male Sprague-Dawley rats (250 g) were anesthetized with an intraperitoneal injection of pentobarbital (5 mg/lOO g body wt), the common bile duct was ligated at two portions, and the abdomen was closed. Untreated rats were used as controls. Three days after, under pentobarbital anesthesia after overnight fasting, the common bile duct was cannulated with a PE-10 tube (Becton Dickinson Primary Care Diagnostics, Franklin Lake, NJ). The femoral vein was cannulated with a 3-Fr venous catheter, and 3% human albumin in a 5% glucose solution (standard solution) was infused at the rate of 2 ml/h during the experiment. The animals were placed in restrictive cages and their body temperature was maintained at 37°C during the experiments. Thirty minutes after bile duct cannulation, BSP (1 pmol/lOO g body wt.), and tracer doses of [3H]LTC, and [14C]EM, or [3H]VLB and [‘4C]PS dissolved in the standard solution (50 ~1) was intravenously injected via the femoral vein. Bile samples were collected every 10 or 15 min for 60 or 90 min and measured for BSP concentration by OD,xo or the radioactivity of 3H and 14C. Data were expressed as means f S.D. Biliary excretion was shown by nmol/ min/lOO g body wt for BSP, and percentage of the total administered dose/l5 min for radiolabeled materials. Although the dead space of the bile duct may have increased in the bile duct-ligated rats, the time delay of bile sampling is considered to have only a minor effect on the results. Statistical analysis was performed by Mann-Whitney’s U-test using a StatView-J 4.02, and P -C 0.05 was considered to indicate significance of differences.
H. Takikawil
et al. / International
Hepatology
Communications
5 (1996)
201-206
203
3. Results Bile flow was increased in the bile duct-ligated rats at the time of the injection of organic anions and gradually decreased with the decrease of the bile acid pool as reported previously [12] (Figs. l-3). Biliary excretion of BSP was markedly delayed in the bile-duct ligated rats (Fig. 1). Biliary excretion of a tracer amount of [3H]lTC, was markedly delayed in the bile ductligated rats (Fig. 2); biliary excretion during 90 min was 67.9 f 9.5% and 15.8 f 6.8% of the administered dose in the control and bile duct-ligated rats, respectively (P < 0.05). Biliary excretion of a tracer dose of [r4C]EM was also markedly delayed in the bile duct-ligated rats (Fig. 2); biliary excretion during 90 min was 35.6 + 9.7% and 9.2 + 4.7% of the administered dose in the control and bile duct-ligated rats, respectively (P < 0.05). Biliary excretion of a tracer amount of [3H]VLB was delayed in the bile duct-ligated rats (Fig. 3); biliary excretion during 60 min was 13.9 & 1.8% and 3.9 _+ 1.3% of the administered dose in the control and bile duct-ligated rats, respectively (P < 0.05). Biliary excretion of a tracer dose of [‘4C]PS was markedly delayed in the bile duct-ligated rats (Fig. 3); biliary excretion during 60 min was 82.8 + 6.3% and 10.3 f 3.0% of the administered dose in the control and bile duct-ligated rats, respectively (P < 0.05).
0
0
60
30
Time
90
(min)
Fig. 1. Biliary excretion of BSP. BSP (1 pmol/lOO g b. wt.) was intravenously administered rats (n = 4, open circles) and bile duct-ligated rats for 3 days (n = 3, closed circles). Values * S.D.
to control are means
204
H. Takikawa
et al. / International
0’
Hepatohgy Communications
5 (1996)
0
30
60
90
0
30
60
90
0
30
60
90
201-206
30
Time (min) Fig. 2. Biliary excretion of 13H]LTC, and [%]EM. Tracer doses of radiolabeled materials were intravenously administered to control rats (n = 4, open circles) and bile duct-ligated rats for 3 days (n = 3, closed circles). Values are means f SD.
4. Discussion
In the bile duct-ligated rats, although biliary excretion of taurocholate was only slightly impaired, its transport maximum was markedly decreased [12]. Furthermore, biliary glutathione excretion was markedly impaired in the bile duct-ligated rats [12]. Biliary excretion of lithocholate-3-0-glucuronide, the excretory pathway of which was considered to be the same as that of organic anions in the studies with mutant hyperbilirubinemic rats [ 13,141, was also markedly impaired. The biliary excretion of BSP and LTC, was also markedly impaired in the bile duct-ligated rats. The impaired biliary excretion of these organic anions may be due to the damage of the ATP-dependent canalicular transporter as suggested by the study with canalicular membrane vesicles of rats with ethinylestradiol-induced cholestasis
[151.
In contrast, the multiplicity of biliary excretion of organic anions has been suggested [16- 181 and biliary excretion of PS, the excretory pathway of which is considered to be distinct from that for BSP and LTC, (Y. Adachi et al. and Y. Sugiyama et al., personal communications), was also markedly impaired in the bile
H. Takikawa
et al. / International
Hepatology
Communications
5 (1994)
201-206
205
duct-ligated rats. These findings suggest that multiple damage of canalicular organic anion carriers occurred in the bile duct-ligated rats, and may also explain the presence of obstructive jaundice patients with consistently high serum bilirubin levels despite of the appropriate bile flow and biliary bile acid excretion after bile drainage. Schrenk et al. reported that the expression of MDR 1 was increased in bile duct-ligated rats [19]. However, the present data showed impaired biliary excretion of VLB in the bile duct-ligated rats. These findings suggest either the involvement of the other excretory pathway for VLB and its damage, or the damage of hepatic uptake or intrahepatic transport of VLB. The multiplicity of canalicular transport of organic cations has recently been reported [20]. The mechanism of biliary EM excretion is poorly understood, and that involved in the marked impairment of EM excretion in the bile duct-ligated rats is unknown. However, a canalicular carrier for organic cations may also be damaged as is that for organic anion.
lp-
0’
.....b .........b .........~ ........~,............ *
30
60
0
30
60
0
30
60
0
4r
Time (min) Fig. 3. Biliary excretion of [3H]VLB and [‘4C]PS. Tracer doses of radiolabeled materials were intravenously administered to control rats (n = 4, open circles) and bile duct-ligated rats for 3 days (n = 6, closed circles). Values are means + S.D.
206
H. Tukikawu
et al. / b~ternatior~al
Hrpatology
Communications
5 (1996)
Xl-206
References [l] Adachi Y. Kobayashi H, Kurumi Y, Shouji M, Kitano M, Yamamoto T. ATP-dependent taurocholate transport by rat liver canalicular membrane vesicles. Hepatology 1991; 14: 6555659. [2] Nishida T. Gatmaitan Z, Che M. Arias IM. Rat liver canalicular membrane vesicles contain an ATP-dependent bile acid transport system. Proc Nat1 Acad Sci USA 1991: 88: 6590-6594. [3] Miiller M, Ishikawa T, Berger U et al. ATP-dependent transport of taurocholate across the hepatocyte canalicular membrane mediated by a 1IO-kDa glycoprotein binding ATP and bile salt. J Biol Chem 1991; 266: 18920-18926. [4] Kitamura T, Jansen P, Hardenbrook C, Kamimoto U, Gatmaitan Z, Arias IM. Defective ATP-dependent canalicular transport of organic anions in mutant (TR-) rats with conjugated hyperbilirubinemia. Proc Nat1 Acad Sci USA 1990; 87: 355773561. [S] Kobayashi K, Sogame Y, Hara H, Hayashi K. Mechanism of glutathione S-conjugate transport in canalicular and basolateral rat liver plasma membranes. J Biol Chem 1990; 265: 773777741. [6] Ishikawa T, Mtiller M, Khinemann C. Schaub T, Keppler D. ATP-dependent primary active transport of cysteinyl leukotrienes across liver canalicular membrane. Role of the ATP-dependent transport system for glutathione conjugates. J Biol Chem 1990: 265: 19279919286. [7] Kamimoto Y, Gatmaitan Z, Hsu J, Arias IM. The function of gp 170, the multidrug resistance gene product, in rat liver canalicular membrane vesicles. J Biol Chem 1989; 264: 11693311698. [8] Watanabe T, Miyauchi S, Sawada Y. et al. Kinetic analysis of hepatobiliary transport of vincristine in perfused rat liver. Possible roles of P-glycoprotein in biliary excretion of vincristine. J Hepatol 1992; 16: 77-88. [9] Mtiller M, Mayer R, Hero U, Keppler D. ATP-dependent transport of amphophilic cations across the hepatocyte canalicular membrane mediated by mdr 1 P-glycoprotein. FEBS Lett 1994; 343: 1688172. [IO] Erlinger S. Secretion of Bile. In: Schiff L, Schiff ER, eds. Diseases of the Liver, 7th edn. Philadelphia, PA: Lippincott, 1993: 85-107. [ll] Ballatori N, Truong AT. Glutathione as primary osmotic driving force in hepatic bile formation. Am J Physiol 1992; 263: G617-G624. [I21 Takikawa H, Wako Y, Sano N, Yamanaka M. Changes in biliary excretory mechanisms in bile duct-ligated rat. Dig Dis Sci 1996; 41: 256-262. [13] Kuipers F, Radominska A, Zimniak P, et al. Defective biliary secretion of bile acid 3-O-glucuronides in rats with hereditary hyperbilirubinemia. J Lipid Res 1989; 30: 1835- 1845. [14] Takikawa H, Sano N, Narita T et al. Biliary excretion of bile acid conjugates in a hyperbilirubinemic mutant Sprague-Dawley rats. Hepatology 1991; 14: 352-360. [15] Bossard R, Stieger B. O’Neill B, Fricker G, Meier PJ. Ethinylestradiol treatment induces multiple canalicular membrane transport alterations in rat liver. J Clin Invest 1992; 263: G617-G624. [16] Sathrakul K, Suzuki H, Yamada T. Hanano M, Sugiyama Y. Multiple transport systems for organic anions across the bile canalicular membrane. J Pharmacol Exp Ther 1992; 268: 6573. [17] Takikawa H, Nishikawa K, Sano N. Yamanaka M, Horie T. Mechanisms of biliary excretion of lithocholate-3-sulfate in Eisai hyperbilirubinemic rats (EHBR). Dig Dis Sci 1995; 40: 1792-1797. [18] Takenaka 0, Horie T, Kobayashi K. Suzuki H, Sugiyama Y. Kinetic analysis of hepatobiliary transport for conjugated metabolites in the perfused liver of mutant rats (EHBR) with hereditary conjugated hyperbilirubinemia. Pharm Res 1995; 12: 1746- 1755. [19] Schrenk D, Gant TW, Presiegger K-H, Silverman JA, Marino PA, Thorgeirson SS. Induction of multidrug resistance gene expression during cholestasis in rats and non-human primates, Hepatology 1993; 17: 8544860. [20] Smit H. Dubin E, Steen H, Roggeveld J, Oosting R. Meijer DKF. Multiple carriers involved in the biliary excretion of cationic drugs. Hepatology 1995; 22: 309A.