Sodium Taurocholate Modifies the Bile Acid-Independent Fraction of Canalicular Bile Flow in the Rhesus Monkey

The use of [14C]erythritol for the quantitative assessment of hepatic bile formation has been studied in baboons using sodium taurocholate to generate canalicular bile flow. It has been found that increments in [14C]erythritol clearance are equal to taurocholate-induced increments in bile flow, but there was no change in [14C]erythritol clearance when bile flow was increased by secretin. No evidence was found to support the view that bile acids affect bile acid-independent bile flow.

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Effect of choleretics on canalicular transport of protoporphyrin in the rat liver

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1982.242.4.g347 ◽

1982 ◽

Vol 242 (4) ◽

pp. G347-G353

Author(s):

D. L. Avner ◽

M. M. Berenson

Keyword(s):

Bile Acid ◽

Acid Secretion ◽

Transport Process ◽

Bile Flow ◽

Ethacrynic Acid ◽

Sodium Taurocholate ◽

Secretory Process ◽

Sodium Dehydrocholate ◽

Major Route ◽

Bile Acid Secretion

The major route of protoporphyrin elimination is biliary secretion. To clarify the nature of the secretory process, maximal canalicular secretion of protoporphyrin was determined under basal conditions and after treatment with various choleretics. The maximal secretion of protoporphyrin under basal conditions was 0.07 +/- 0.01 micrograms.min-1.100 g body wt-1. Infusion of physiological amounts of sodium taurocholate increased protoporphyrin secretion 13-fold (0.90 +/- 0.02), primarily by increasing the biliary protoporphyrin concentration. Biliary protoporphyrin secretion tended to plateau in spite of a continued rise in both biliary bile acid secretion and concentration. Infusion of sodium dehydrocholate increased protoporphyrin secretion, but to only 35% of that achieved by sodium taurocholate. Ethacrynic acid and phenobarbital increased bile flow over controls but failed to enhance protoporphyrin transport. Thus, canalicular secretion of protoporphyrin was maximally enhanced by micelle-forming bile acids and unaffected by nonbile acid choleretics. The observed limitation of protoporphyrin secretion may be related to achievement of a canalicular transport maximum or to a toxic effect of protoporphyrin on the transport process.

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Effect of protoporphyrin IX on ursodeoxycholate-induced hypercholeresis in the rat

Clinical Science ◽

10.1042/cs0750593 ◽

1988 ◽

Vol 75 (6) ◽

pp. 593-599

Author(s):

J. J. Garcia-Marin ◽

J. G. Redondo-Torres ◽

F. Perez-Barriocanal ◽

M. M. Berenson

Keyword(s):

Body Weight ◽

Bile Acid ◽

Bile Flow ◽

Sodium Taurocholate ◽

Protoporphyrin Ix ◽

Inhibitory Effect ◽

Bicarbonate Secretion ◽

Bile Formation ◽

Dose Dependent ◽

Bile Acid Secretion

1. It is known that the perfusion of rat livers with solutions containing protoporphyrin IX induces a decrease in bile flow which is not due to inhibition of bile acid secretion but rather to decreased electrolyte transport into bile. By contrast, ursodeoxycholate induces hypercholeresis, partly due to a marked stimulation of biliary bicarbonate secretion. The aim of the present work was to investigate the effect of protoporphyrin IX on ursodeoxycholate-induced choleresis in anaesthetized male Wistar rats. 2. Protoporphyrin IX infusion at rates of 10, 20 and 40 μg min−1 100 g−1 body weight into the jugular vein induced a dose-dependent inhibitory effect on bile flow as well as on bile acid and electrolyte secretion. The lowest infused rate only induced slight and non-significant changes in spontaneous bile formation and functional variables such as glycaemia, packed cell volume, blood pH, Pco2, Po2 and bicarbonate concentration, and in hepatic carbonic anhydrase activity. It was thus considered as a subtoxic dose. 3. Sodium taurocholate was infused (0.5 μmol min−1 100 g−1 body weight) over the second hour of the lowest dose of protoporphyrin IX infusion. In these rats, no significant changes in bile flow or bile acid and electrolyte secretion were observed as compared with animals receiving sodium taurocholate plus saline solution. 4. Bile acid secretion induced by ursodeoxycholate infusion (1 μmol min−1 100 g−1 body weight) was similar both in rats receiving ursodeoxycholate plus saline solution and in animals infused with this bile acid over the second hour of the lowest dose of protoporphyrin IX infusion. However, bile flow and biliary bicarbonate secretion induced by ursodeoxycholate were markedly impaired (− 43% and − 56%, respectively) by protoporphyrin IX. 5. These results indicate that in the rat, in vivo, protoporphyrin IX impairs bile formation in a dose-dependent manner. They suggest that the mechanism(s) involved in ursodeoxycholate-induced bicarbonate secretion, and hence hypercholeresis, are particularly sensitive to the inhibitory effect of protoporphyrin IX.

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Regulatory volume decrease stimulates bile flow, bile acid excretion, and exocytosis in isolated perfused rat liver

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1992.262.5.g806 ◽

1992 ◽

Vol 262 (5) ◽

pp. G806-G812 ◽

Cited By ~ 2

Author(s):

R. Bruck ◽

P. Haddad ◽

J. Graf ◽

J. L. Boyer

Keyword(s):

Bile Acid ◽

Bile Flow ◽

Sodium Taurocholate ◽

Regulatory Volume Decrease ◽

Acid Excretion ◽

K Channels ◽

Hypotonic Stress ◽

Bile Acid Excretion ◽

Second Peak ◽

Volume Decrease

To study the effect of volume regulation on bile secretory function, isolated perfused rat livers (IPRL) were exposed to hypotonic stress (45 mM NaCl) while bile flow and the biliary excretion of bile acids and horseradish peroxidase (HRP) were assessed. Hypotonic stress induced a biphasic increase in bile flow, which rose in the first minute from 1.1 +/- 0.2 to 1.7 +/- 0.1 microliter.min-1.g liver-1 (P less than 0.01), an effect attributed to rapid osmotic equilibration of water, then increased further between 3 and 5 min to 1.6 +/- 0.1 microliter.min-1.g liver-1 (P less than 0.01, followed by a subsequent return to baseline. HRP excretion in bile increased during the second peak of bile flow from 0.9 +/- 0.2 to 1.1 +/- 0.2 ng.min-1.g liver-1, P less than 0.01. Pretreatment with colchicine but not lumicolchicine completely abolished the latter increase in bile flow and HRP excretion as did BaCl2 (1 mM), an inhibitor of both K+ channels and regulatory volume decrease (RVD) in hepatocytes. When sodium taurocholate was infused (1 mumol/min), hypotonic stress induced an even larger increase in the second peak of bile flow (5.1 +/- 0.7 microliters/g liver, P less than 0.01) and higher rates of bile acid excretion than in control perfusions with bile acid (126.2 +/- 21.0 vs. 99.0 +/- 17.1 nmol.min-1.g liver-1, P less than 0.05). These data suggest that both bile flow and bile acid excretion are stimulated during RVD by mechanisms that involve both K+ channels and microtubule-dependent exocytosis at the canalicular (apical) membrane domain.

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Erythritol and mannitol clearances with taurocholate and secretin-induced cholereses.

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1978.234.2.e146 ◽

1978 ◽

Vol 234 (2) ◽

pp. E146

Author(s):

J L Barnhart ◽

B Combes

Keyword(s):

Bile Flow ◽

Total Concentration ◽

Sodium Taurocholate ◽

Fixed Amount ◽

Bile Formation ◽

Canalicular Bile ◽

Wide Range ◽

Bile Production ◽

Mean Concentration ◽

Erythritol And Mannitol

The biliary clearances of [14C]erythritol (Cery) and [3H]mannitol (Cmann) were measured simultaneously in dogs during cholereses induced by sodium taurocholate and by secretin. Cery increased equally with the increase in bile flow induced by taurocholate, whereas mannitol entry into bile was partially restricted; deltaCery/deltabile flow averaged 0.96; deltaCmann/deltaCery averaged 0.81. Values for erythritol clearance exceeded bile flow by a constant volume over a wide range of bile flows, a result that suggests distal reabsorption of a fixed amount of fluid, independent of canalicular bile production. During secretin-induced choleresis both Cery and Cmann accompanied 30-40% of the increase in bile flow, and the ratio of Cmann/Cery was 1.02. Thus the secretin-responsive region is permeable to both erythritol and mannitol. This affects the extent to which measured erythritol clearance accurately reflects canalicular bile formation; Cery may underestimate or overestimate canalicular bile flow. The electrolyte composition of bile remained relatively constant over a broad range of bile flows although the characteristics of taurocholate- and secretin-induced biles differed from each other. Taurocholate-stimulated bile was virtually isotonic. Secretin-induced bile had a high total concentration of electrolyte (mean concentration 367 meq/liter) rich in chloride and bicarbonate and was hypertonic.

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History of hepatic bile formation: old problems, new approaches

AJP Advances in Physiology Education ◽

10.1152/advan.00076.2014 ◽

2014 ◽

Vol 38 (4) ◽

pp. 279-285 ◽

Cited By ~ 2

Author(s):

Norman B. Javitt

Keyword(s):

Bile Acid ◽

Bile Acids ◽

Water Flow ◽

Bile Flow ◽

Water Movement ◽

Sodium Taurocholate ◽

Biliary System ◽

Hepatic Bile ◽

Bile Formation ◽

Osmotic Effect

Studies of hepatic bile formation reported in 1958 established that it was an osmotically generated water flow. Intravenous infusion of sodium taurocholate established a high correlation between hepatic bile flow and bile acid excretion. Secretin, a hormone that stimulates bicarbonate secretion, was also found to increase hepatic bile flow. The sources of the water entering the biliary system with these two stimuli were differentiated by the use of mannitol. An increase in its excretion parallels the increase in bile flow in response to bile acids but not secretin, which led to a quantitative distinction between canalicular and ductular water flow. The finding of aquaglyceroporin-9 in the basolateral surface of the hepatocyte accounted for the rapid entry of mannitol into hepatocytes and its exclusion from water movement in the ductules where aquaporin-1 is present. Electron microscopy demonstrated that bile acids generate the formation of vesicles that contain lecithin and cholesterol after their receptor-mediated canalicular transport. Biophysical studies established that the osmotic effect of bile acids varies with their concentration and also with the proportion of mono-, di-, and trihydroxy bile acids and provides a basis for understanding their physiological effects. Because of the varying osmotic effect of bile acids, it is difficult to quantify bile acid independent flow generated by other solutes, such as glutathione, which enters the biliary system. Monohydroxy bile acids, by markedly increasing aggregation number, severely reduce water flow. Developing biomarkers for the noninvasive assessment of normal hepatic bile flow remains an elusive goal that merits further study.

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Short- and long-term effects of biliary drainage on hepatic cholesterol metabolism in the rat

Biochemical Journal ◽

10.1042/bj2690781 ◽

1990 ◽

Vol 269 (3) ◽

pp. 781-788 ◽

Cited By ~ 17

Author(s):

M J Smit ◽

A M Temmerman ◽

R Havinga ◽

F Kuipers ◽

R J Vonk

Keyword(s):

Bile Acid ◽

Bile Flow ◽

Cholesterol Metabolism ◽

Acid Output ◽

Biliary Secretion ◽

Surgical Trauma ◽

Hepatic Cholesterol ◽

Long Term Effects ◽

Short And Long Term

The present study concerns short- and long-term effects of interruption of the enterohepatic circulation (EHC) on hepatic cholesterol metabolism and biliary secretion in rats. For this purpose, we employed a technique that allows reversible interruption of the EHC, during normal feeding conditions, and excludes effects of anaesthesia and surgical trauma. [3H]Cholesteryl oleate-labelled human low-density lipoprotein (LDL) was injected intravenously in rats with (1) chronically (8 days) interrupted EHC, (2) interrupted EHC at the time of LDL injection and (3) intact EHC. During the first 3 h after interruption of the EHC, bile flow decreased to 50% and biliary bile acid, phospholipid and cholesterol secretion to 5%, 11% and 19% of their initial values respectively. After 8 days of bile diversion, biliary cholesterol output and bile flow were at that same level, but bile acid output was increased 2-3-fold and phospholipid output was about 2 times lower. The total amount of cholesterol in the liver decreased after interruption of the EHC, which was mainly due to a decrease in the amount of cholesteryl ester. Plasma disappearance of LDL was not affected by interruption of the EHC. Biliary secretion of LDL-derived radioactivity occurred 2-4 times faster in chronically interrupted rats as compared with the excretion immediately after interruption of the EHC. Radioactivity was mainly in the form of bile acids under both conditions. This study demonstrates the very rapid changes that occur in cholesterol metabolism and biliary lipid composition after interruption of the EHC. These changes must be taken into account in studies concerning hepatic metabolism of lipoprotein cholesterol and subsequent secretion into bile.

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NTCP oligomerization occurs downstream of the NTCP-EGFR interaction during hepatitis B virus internalization

Journal of Virology ◽

10.1128/jvi.00938-21 ◽

2021 ◽

Author(s):

Kento Fukano ◽

Mizuki Oshima ◽

Senko Tsukuda ◽

Hideki Aizaki ◽

Mio Ohki ◽

...

Keyword(s):

Epidermal Growth Factor Receptor ◽

Bile Acid ◽

Hepatitis B Virus ◽

Hepatitis B ◽

Viral Entry ◽

Sodium Taurocholate ◽

Growth Factor Receptor ◽

Host Cells ◽

B Virus ◽

Epidermal Growth

Sodium taurocholate cotransporting polypeptide (NTCP) is a receptor that is essential for hepatitis B virus (HBV) entry into the host cell. A number of HBV entry inhibitors targeting NTCP have been reported to date; these inhibitors have facilitated a mechanistic analysis of the viral entry process. However, the mechanism of HBV internalization into host cells after interaction of virus with NTCP remains largely unknown. Recently, we reported that troglitazone, a thiazolidinedione derivative, specifically inhibits both HBV internalization and NTCP oligomerization, resulting in inhibition of HBV infection. Here, using troglitazone as a chemical probe to investigate entry process, the contribution of NTCP oligomerization to HBV internalization was evaluated. Using surface plasmon resonance and transporter kinetics, we found that troglitazone directly interacts with NTCP and non-competitively interferes with NTCP-mediated bile acid uptake, suggesting that troglitazone allosterically binds to NTCP, rather than to the bile acid-binding pocket. Additionally, alanine scanning mutagenesis showed that a mutation at phenylalanine 274 of NTCP (F274A) caused a loss of HBV susceptibility and disrupted both the oligomerization of NTCP and HBV internalization without affecting viral attachment to the cell surface. An inhibitor of the interaction between NTCP and epidermal growth factor receptor (EGFR), another host cofactor essential for HBV internalization, impeded NTCP oligomerization. Meanwhile, co-immunoprecipitation analysis revealed that neither troglitazone nor the F274A mutation in NTCP affect the NTCP-EGFR interaction. These findings suggest that NTCP oligomerization is initiated downstream of the NTCP-EGFR interaction, and then triggers HBV internalization. This study provides significant insight into the HBV entry mechanisms. Importance Hepatitis B virus (HBV) infection is mediated by a specific interaction with sodium taurocholate cotransporting polypeptide (NTCP), a viral entry receptor. Although the virus-receptor interactions are believed to trigger viral internalization into host cells, the exact molecular mechanisms of HBV internalization are not understood. In this study, we revealed the mode of action whereby troglitazone, a specific inhibitor of HBV internalization, impedes NTCP oligomerization, and identified NTCP phenylalanine 274 as a residue essential for this oligomerization. We further analyzed the association between NTCP oligomerization and HBV internalization, a process that is mediated by epidermal growth factor receptor (EGFR), another essential host cofactor for HBV internalization. Our study provides critical information on the mechanism of HBV entry, and suggests that oligomerization of the viral receptor serves as an attractive target for drug discovery.

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