Changes in biliary excretory mechanisms in bile duct-ligated rat

The effects of bile duct ligation on biliary excretion of bile acids, glutathione, and lipids were studied in the rat. The bile duct of the rat was ligated for three days. The biliary bile acid excretion after bile duct cannulation was higher at first, but after 90 min became lower than that in the control rat. The bile flow in the bile duct-ligated rat was higher after bile duct cannulation and gradually decreased to the same level as in the control rat. Biliary glutathione excretion, which has been suggested to be a driving force for the bile acid-independent canalicular bile flow, was markedly decreased in the bile duct-ligated rat. The mannitol clearance was increased and the bile ductules showed proliferation in the bile duct-ligated rat, suggesting an increase in the ductular bile flow. Biliary excretion of lithocholate glucuronide was more markedly impaired than that of taurocholate. When taurocholate was infused at higher rates, which increases bile flow and biliary excretion of bile acid and lipids in the control rat, biliary bile acid and lipid excretion remained constant in the bile duct-ligated rat. These findings indicate that, in the bile duct-ligated rat, the ductular bile flow was increased and bile acid-independent canalicular bile flow was decreased and that, although the biliary excretion of bile acids was not as impaired as that of organic anions, the capacity of bile acid and lipid excretion was markedly decreased.     

胆汁的分泌、排泄和调节及胆汁淤积发生机制

胆汁的形成、分泌和排泄机制十分复杂,肝细胞和胆管细胞都具有摄取和分泌胆汁成分的功能,这主要依靠肝细胞和胆管细胞膜上的转运蛋白,其在肝脏的病理和生理过程中占有重要的地位。胆汁淤积可以由肝细胞内胆汁形成的功能性缺陷所致,也可由于小胆管或胆管内胆汁分泌或流动的障碍所致。本文就胆汁分泌、排泄和调节及胆汁淤积发生机制等方面进行了论述     

Effect of ursodeoxycholic acid administration on bile duct proliferation and cholestasis in bile duct ligated rat

The origin, mechanism, and significance of the bile duct proliferation (BDP) associated with cholestasis remain unexplained. This study examined the effect of oral administration of ursodeoxycholic acid (UDCA) on both BDP and cholestasis in the rat. After bile duct ligation, male Sprague-Dawley rats were treated for 30 days with either UDCA (5 mg/day) (group A) or saline solution (group B). Animals were sacrificed at day 30. The serum activity of aminotransferase (ALT, AST), alkaline phosphatase, and -glutamyltransferase (GGT) was significantly lower (P<0.01) in the UDCA-treated rats. Total serum bilirubin and total serum bile acids were lower (P<0.001) in group A. Moreover, the control of BA in bile was reduced also (P<0.02). Conversely, serum cholesterol levels were not different between the two groups. Histological examination showed that the number of ductular cells in the portal areas was significantly (P<0.001) reduced in UDCA-treated as compared to saline-treated rats. The replication activity, assessed as the number of bromodeoxyuridine-positive cells, was also significantly lower in treated animals (33±11 vs 64±22 per 1000 cells;P<0.001). Lobular bile ductules were three times larger in group B, and extrahepatic duct measurements confirmed this increase in size of the larger biliary ducts (P<0.001). These findings demonstrate that UDCA reduces BDP in response to BD ligation. Although the mechanism(s) of this effect is still hypothetical, UDCA may reduce the level of irritating bile salts such as chenodeoxycholic acid and lithocolate and increase periductular bile acid recirculation. These data support the beneficial effect of UDCA treatment in chronic cholestatic disease.     

Biliary excretion of bile acids and organic anions in rats with dichloroethylene-induced bile canalicular injury

Background Hepatocytes in zone 1 of the hepatic lobule play a role in the uptake and biliary excretion of bile acids and organic anions under physiological conditions, and hepatocytes in zone 3 may play a role only when there is a high-dose load. To further elucidate the role of hepatic zonation in the hepatic handling of bile acids and organic anions, the biliary excretion of these compounds was studied in rats with dichloroethylene (DCE)-induced selective zone 3 bile canalicular injury.Methods Biliary excretion of various bile acids and organic anions was studied in rats 1h after oral administration of DCE (5mg/100g). The effect of DCE on the immunostaining of multidrug resistance protein 2 (Mrp2; an important canalicular organic anion transporter) in the liver was also examined.Results The biliary excretory maximum of taurocholate and tauroursodeoxycholate was decreased in DCE-treated rats, whereas the biliary excretion of taurolithocholate-sulfate and phenolphthalein-glucuronide was unchanged in DCE-treated rats, and DCE treatment decreased the biliary excretion of sulfobromophthalein and pravastatin. DCE decreased Mrp2 staining in the canalicular membrane of zone 3 hepatocytes on immunohistochemistry.Conclusions These findings indicate that canalicular transport in zone 3 hepatocytes is important in the biliary excretion of bile acids and organic anions, when they are administered at high doses.     

Effects of lipopolysaccharide on the biliary excretion of bile acids and organic anions in rats

BACKGROUND: Lipopolysaccharide is known to be a cause of cholestasis associated with sepsis. It has also recently been reported to down-regulate the basolateral and canalicular transporters. The aim of the present study was to examine simultaneously the effect of lipopolysaccharide on the biliary excretion of typical substrates of bile salt export pump and multidrug resistance protein 2 in vivo, and the effect of lipopolysaccharide on the amount of these transporters. METHODS: After intravenous administration of O127:B8-derived lipopolysaccharide (2.5 mg/kg), the biliary excretion of taurocholate and various organic anions was studied, and the protein levels of bile salt export pump and multidrug resistance protein 2 in the crude liver membrane was determined by western blot analysis. RESULTS: Lipopolysaccharide decreased the biliary excretion of tracer amounts of taurocholate, leukotriene C4, taurolithocholate-3-sulfate and temocapril without affecting bile flow. The biliary excretion of high doses of taurocholate and sulfobromophthalein was markedly inhibited by lipopolysaccharide. Lipopolysaccharide decreased bile salt export pump levels in the liver plasma membrane fraction to 48% of control rats, and markedly decreased multidrug resistance protein 2 levels to 17% of control rats. CONCLUSIONS: These findings support the hypothesis that down-regulation of the canalicular transporters by lipopolysaccharide causes the impairment of the biliary excretion of bile acids and organic anions in cholestasis of sepsis prior to the decrease of bile flow.     

Chronic administration of aminoguanidine reduces vascular nitric oxide production and attenuates liver damage in bile duct-ligated rats.

BACKGROUND: Nitric oxide (NO) has been implicated in the pathogenesis of liver cirrhosis. This study investigated the activity of nitric oxide synthase (NOS) in cirrhosis induced by bile duct-ligation (BDL) with NOS inhibitors. METHOD: Three days after operation, rats were randomized to receive aminoguanidine (AG, 25 mg/kg/day) or L-N(G)-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg/day) for 21 days. RESULTS: Vascular NO production, which was increased in BDL cirrhotic rats, was reduced by 75% with AG but not L-NAME chronic administration. AG treatment attenuated liver damage, while L-NAME aggravated it. AG significantly suppressed inducible NOS (iNOS) expression in aorta of BDL rats at both mRNA and protein level, but much less efficient in reducing it in liver. In contrast, endothelial NOS (eNOS) expression was not markedly affected. Calcium-independent NOS activity, which was dramatically increased in aorta of BDL rats, was abolished by AG treatment. In liver, however, both calcium-dependent and -independent NOS activity were increased by AG treatment. CONCLUSION: Chronic administration of AG could reduce systemic NO levels as well as suppress iNOS expression and activity in aorta of BDL rats. It also improved liver function, possibly because of its ability to increase hepatic NOS activity, and to correct the systemic hemodynamic disorders by decreasing vascular NO production.     

The biliary excretion and pharmacokinetics of mezlocillin in jaundiced patients with external bile drainage

ABSTRACT— The biliary excretion and pharmacokinetics of mezlocillin have been studied in jaundiced patients with total external bile drainage through a percutaneous transhepatic catheter. In 10 of 11 studies, 2 g mezlocillin intravenously resulted in biliary concentrations sufficient to exceed the minimum inhibitory concentrations of most common biliary pathogenic organisms. In 6 h, 0.2–6.2% of the dose given was recovered in bile. The biliary clearance was 0.21–7.82 ml/min and increased with the duration of biliary decompression. The serum half-life of mezlocillin was prolonged (1.81 ± 0.23 h, mean ± SD), and was due to reduced biliary and renal clearance.     

Effects of secretin on bile production in two kinds of cholestatic models by choledocho-caval fistula and bile duct ligation in rats

Secretin is known to stimulate bile flow from the bile duct epithelium. To investigate the effects of secretin in cholestasis, we studied the response of the bile flow and the excretion of biliary components to secretin using two cholestatic models with or without damage to the bile duct epithelium. The model without bile duct epithelial damage was a choledocho-caval (CC) fistula over a 24-hour period, and the model with bile duct damage was a bile duct ligation over a 48-hour period. Secretin was administered by intravenous infusion for 30 minutes and bile was collected for 120 minutes. Controls were given saline similarly. The bile flow and biliary bicarbonate excretion rate were significantly increased after secretin infusion in the CC fistula rats when compared with the control rats, but no stimulation by secretin was observed in the ligated rats. These data indicate that secretin-induced bile production was enhanced under cholestatic conditions with no bile duct epithelial disturbance.     

Bile canaliculi morphology after bile duct ligation in the rat with portacaval shunt: a time course study

ABSTRACT— Besides the spontaneous occurrence of portacaval shunts in chronic liver diseases and the performance of shunt to cure portal hypertension, shunts are now proposed for the treatment of some metabolic diseases, especially in children. The portacaval shunt model in the rat, known to induce liver atrophy related to hepatocyte loss and atrophy, was used to investigate morphological liver changes occurring in cholestasis. Two weeks after portacaval or sham portacaval shunt, the bile duct was ligated and livers were examined by light and electron microscopy at 5 h, 20 h, 4 days and 8 days. Portal inflammatory reaction and proliferation of bile ducts were identical but areas of patchy hepatic necrosis were more numerous in shunted rats. Hepatocyte size decreased in the sham group but increased in the other group. Hepatocyte ultrastructural changes were similar in the two groups. At 5 h, the number of bile canaliculi sections increased (X2) and 95% of them were normal. As time elapsed, the ratio of dilated bile canaliculi without microvilli and of bile canaliculi filled with cytoplasmic blebs increased but in no case reached 50% of the total. These results show that in the rat, cholestasis induced by bile duct ligation has approximately the same characteristics in control or shunted animals.     

Urinary bile acid sulfate levels in patients with primary biliary cirrhosis

Aim: Urinary bile acids are mainly conjugated with sulfuric acid. In a previous work, we demonstrated that the levels of urinary sulfated bile acids (USBA) and serum total bile acids (TBA) were correlated very well and also that USBA was considered to be a more useful indicator of hepatic fibrosis than TBA in patients with hepatitis C virus (HCV)‐related liver diseases. In the current study we aimed to confirm these finding in patients with primary biliary cirrhosis (PBC), a prototypic cholestatic liver disease. Methods: Urinary sulfated bile acids were measured using an automatic assay kit in 50 patients with PBC, of whom 11 were diagnosed as having cirrhosis. We obtained specimens before ursodeoxycholic acid (UDCA) administration in four patients, and during UDCA in 46 patients. The correlations between USBA and various laboratory tests were studied. Results: The median USBA level was 67.9 µmol/g creatinine in PBC; 27.7 without cirrhosis and 210.3 with cirrhosis (P = 0.001). The number of PBC patients with elevated USBA was significantly higher than those with elevated TBA (82% vs. 56%). This significance was remarkable especially in early stages, non‐cirrhotic patients (77% vs. 49%). USBA level was well correlated with TBA (r_s = 0.72), and negatively correlated with platelet (r_s = ?0.34) and albumin (r_s = ?0.31). Conclusion: Urinary sulfated bile acids and TBA are well correlated, and together with the findings that USBA is not affected by meals, USBA is considered to be more beneficial and convenient than TBA for earlier detection of fibrosis in PBC.     

Biliary excretion of sulfated bile acids and organic anions in zone 1- and zone 3-injured rats

Background and Aims: There are several reports on the biliary excretion of bile acids and organic anions in zone 1‐ and zone 3‐injured rat liver, but the results are controversial. In order to dissolve the discrepancy between previous works about the role of hepatic zonation on the hepatic handling of the substrates of multidrug resistance protein 2, the biliary excretion of sulfated bile acids, pravastatin and phenolphthalein glucuronide was studied in zone 1‐ and zone 3‐injured rats. Methods: Zone 1 and zone 3 injury were caused by allyl alcohol and bromobenzene, respectively. Bile acid sulfates, pravastatin and phenolphthalein glucuronide were administered i.v. to bile duct‐cannulated rats, and their biliary excretion was studied. Results: The biliary excretion of a tracer dose of taurolithocholate‐3‐sulfate and its excretory maximum were unchanged in zone 1 injury, but were diminished in zone 3 injury, whereas the biliary excretion of taurochenodeoxycholate‐3‐sulfate was unchanged in zone 1 and zone 3 injury. The biliary excretion of pravastatin and phenolphthalein glucuronide was markedly decreased only in zone 3 injury, whereas the excretory maximum of phenolphthalein glucuronide was decreased in both zone 1 and zone 3 injury. Conclusions: These findings indicate that zone 3 is important for the biliary excretion of substrates of multidrug resistance protein 2.     

胆总管结扎诱导大鼠肝肺综合征模型的建立初步研究

目的 探讨胆总管结扎术诱导大鼠肝肺综合征(HPS)模型的建立.方法 40只SD大鼠被随机分为实验组30只和对照组(假手术组)10只,采用胆总管结扎术建立肝硬化和HPS模型.使用血气分析仪测定PaO2、PaCO2和pH.结果 在术后1 w,腹部超声检查显示实验组肝脏回声增粗,胆总管轻度扩张.在术后2 w,肝脏被膜不平整,...     

Effect of bile acids on the biliary excretion of pravastatin in rats

Aim: The biliary excretion of pravastatin, an HMG‐CoA reductase inhibitor, is mediated by the multidrug resistance protein 2, but a recent report suggests that pravastatin is also a substrate of the bile salt export pump, which transports bile acids. We examined the effects of bile acids on biliary pravastatin excretion in rats. Methods: The effect of taurocholate on biliary pravastatin excretion, and that of pravastatin on biliary taurocholate excretion was examined in bile‐drained rats. Results: Taurocholate had no effect on biliary pravastatin excretion, whereas pravastatin with a dose to cause biliary excretory maximum significantly inhibited biliary taurocholate excretion. Conclusion: These data indicate that increased serum bile acids will not affect the pharmacokinetics of pravastatin in patients with hepatobiliary diseases. Although pravastatin inhibited biliary taurocholate excretion, it is unlikely that pravastatin significantly inhibits biliary bile acid excretion by its therapeutic doses.     

Change in serum and biliary esterified bile acids in patients with extrahepatic cholestasis during percutaneous transhepatic cholangiodrainage

Eighteen patients with total extrahepatic cholestasis undergoing PTCD were classified into three groups, depending on the bilirubin decrease rate at two weeks after PTCD. Serum and biliary esterified bile acids in each group were measured before PTCD and at 24 hours, 48 hours, 1 week, and 2 weeks after PTCD. Bile acids were measured by Okuyama’s methods (HPLC), and esterified bile acids were calculated from the difference between samples treated with sulfatase or β-glucuronidase for enzymatic hydrolysis and untreated samples measured at the same time. The following results were obtained. The percentages of biliary esterified bile acids in total bile acids were as follows: before PTCD, in the fair improvement group, sulfate (S) = 6.4 ± 4.6 % (mean ± S.D.), glucuronide (G) = 11.7 ± 9.0 % ; in the poor improvement group, S = 2.8 ± 1.6 %, G = 1.0 ± 0.9 % and at 24 hours after PTCD, in the fair group, S = 9.1 ± 7.5 %, G = 7.5 ± 4.3 % ; in the poor group, S = 2.9 ± 2.4 %, G =1.7 ± 1.1 %. The percentages of esterified bile acids in the fair group were higher than in the poor group, and significant differences were noted in G (p<0.05). Thus PTCD is expected to reduce jaundice in cases with high percentages of biliary esterified bile acids before and shortly after PTCD.     

Urinary bile acid sulfate levels in patients with hepatitis C virus-related chronic liver diseases

Aim:  Urinary bile acids are mainly conjugated with sulfuric acid, and urinary sulfated bile acid (USBA) levels in hepatobiliary diseases have been reported. However, the relationship between USBA and fasting serum total bile acid (TBA) has not been studied in hepatobiliary diseases. In the present study, we measured USBA levels in patients with hepatitis C virus-related chronic liver diseases, and the relationship between TBA and various laboratory tests was studied.
Methods:  USBA was measured using an automatic assay kit in 66 patients with chronic hepatitis and 28 patients with liver cirrhosis, and its relationship between TBA and various laboratory tests was studied.
Results:  The median USBA level was 10.7 µmol/g creatinine in patients with chronic hepatitis and 41.1 µmol/g creatinine in liver cirrhosis ( P  = 0.000). More patients with chronic hepatitis had elevated USBA levels (61%) compared to TBA level (39%) ( P  = 0.002). USBA level was well correlated with TBA (r_s = 0.680), and negatively correlated with albumin (r_s = −0.488), prothrombin time (r_s = −0.385) and platelet counts (r_s = −0.394). In patients with liver cirrhosis, USBA was significantly elevated in Child–Pugh class B compared to Child–Pugh class A ( P  = 0.036).
Conclusion:  Although the metabolic pathways of USBA and TBA are different, these levels correlated very well, and USBA is considered to be a useful indicator of hepatic function like TBA in patients with chronic hepatitis C.     

Common bile duct blood clot: an unusual cause of ductal filling defects for calculi

We report a case of obstructive jaundice caused by a blood clot in the common bile duct in a 75-year-old man with cirrhosis. Five years prior to his admission, he had undergone a left hepatectomy for hepatocellular carcinoma. At the present admission, he appeared icteric, and endoscopic retrograde cholangiography revealed filling defects in the common bile duct. Choledochotomy was therefore performed for possible common duct stones, and exploration of the duct showed blood clot casts filling the duct. The casts were easily removed, and the patient's postoperative course was uneventful. However, he developed ascites and jaundice 1 month later and died of liver failure approximately 3 months after undergoing the choledochotomy. Autopsy revealed hemorrhagic necrosis in the proximal intrahepatic duct of the posterior segment, which was considered to be the cause of the observed hemobilia, as well as the blood clot in the common bile duct at surgery. We report this rare case and discuss the cause of hemobilia. Received: March 27, 1998/Accepted: November 27, 1998     

Experimental study on the relationship of bile acids and myocardium damage in obstructive jaundice

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