scholarly journals Immunoperoxidase localization of bile salts in rat liver cells. Evidence for a role of the Golgi apparatus in bile salt transport.

1988 ◽  
Vol 82 (4) ◽  
pp. 1173-1182 ◽  
Author(s):  
Y Lamri ◽  
A Roda ◽  
M Dumont ◽  
G Feldmann ◽  
S Erlinger
Keyword(s):  
Golgi Apparatus ◽  
Bile Salt ◽  
Rat Liver ◽  
Bile Salts ◽  
Liver Cells ◽  
Salt Transport ◽  
Rat Liver Cells ◽  
Bile Salt Transport

Electrogenicity of Na-coupled bile salt transport in isolated rat hepatocytes

1993 ◽  
Vol 265 (1) ◽  
pp. G73-G80
Author(s):  
S. A. Weinman ◽  
R. P. Weeks
Keyword(s):  
Bile Salt ◽  
Bile Salts ◽  
Input Resistance ◽  
Rat Hepatocytes ◽  
Salt Transport ◽  
Isolated Rat Hepatocytes ◽  
Voltage Change ◽  
Uptake Rates ◽  
Dependent Transport ◽  
Bile Salt Transport

The importance of membrane voltage in uptake of bile salts into hepatocytes is not known. Electrogenicity of the primary bile salt transport process, Na-bile salt cotransport, has been difficult to determine because the large K and Cl conductances of the sinusoidal membrane (GK and GCl, respectively) obscure any transport associated currents. In the present study hepatocytes were treated to reduce these membrane conductances and electrogenic entry of taurocholate and glycocholate was demonstrated. Intracellular voltage and resistance changes resulting from bile salt transport were measured in hepatocytes in which GK and GCl were blocked by impalement with Na acetate microelectrodes and external exposure to quinine (400 microM). This increased the cell input resistance from 153 +/- 17 to 230 +/- 17 M omega (n = 14, P < 0.001). Under these conditions, exposure to 100 microM of taurocholate or glycocholate produced Na-dependent depolarizations of 3.0 +/- 0.5 and 4.2 +/- 0.8 mV, respectively. These correspond to transport currents of 13.9 and 7.6 pA/cell, which are comparable to those predicted from known [3H]taurocholate uptake rates if one positive charge enters the cell with each bile salt molecule. Although uptake of these two bile salts was electrogenic, this was not the case for all bile salts. Na-dependent transport of taurodehydrocholate, which occurs at similar rates to that for taurocholate, produced no voltage change. The unconjugated bile salts cholate and ursodeoxycholate also produced no measurable voltage or resistance changes. In conclusion, Na-dependent uptake of taurocholate and glycocholate is electrogenic, whereas uptake of taurodehydrocholate, ursodeoxycholate, and cholate is predominantly electroneutral.(ABSTRACT TRUNCATED AT 250 WORDS)

Bile Salt Transporters: Molecular Characterization, Function, and Regulation

2003 ◽  
Vol 83 (2) ◽  
pp. 633-671 ◽  
Author(s):  
Michael Trauner ◽  
James L. Boyer
Keyword(s):  
Bile Salt ◽  
Molecular Characterization ◽  
Bile Salts ◽  
Organic Anion ◽  
Transport Proteins ◽  
Salt Transport ◽  
Transport Systems ◽  
Cholestatic Liver Disease ◽  
Bile Salt Transporters ◽  
Bile Salt Transport

Molecular medicine has led to rapid advances in the characterization of hepatobiliary transport systems that determine the uptake and excretion of bile salts and other biliary constituents in the liver and extrahepatic tissues. The bile salt pool undergoes an enterohepatic circulation that is regulated by distinct bile salt transport proteins, including the canalicular bile salt export pump BSEP (ABCB11), the ileal Na+-dependent bile salt transporter ISBT (SLC10A2), and the hepatic sinusoidal Na+- taurocholate cotransporting polypeptide NTCP (SLC10A1). Other bile salt transporters include the organic anion transporting polypeptides OATPs (SLC21A) and the multidrug resistance-associated proteins 2 and 3 MRP2,3 (ABCC2,3). Bile salt transporters are also present in cholangiocytes, the renal proximal tubule, and the placenta. Expression of these transport proteins is regulated by both transcriptional and posttranscriptional events, with the former involving nuclear hormone receptors where bile salts function as specific ligands. During bile secretory failure (cholestasis), bile salt transport proteins undergo adaptive responses that serve to protect the liver from bile salt retention and which facilitate extrahepatic routes of bile salt excretion. This review is a comprehensive summary of current knowledge of the molecular characterization, function, and regulation of bile salt transporters in normal physiology and in cholestatic liver disease and liver regeneration.

Ceruloplasmin Expression in Rat Liver Cells is Attenuated by Insulin: Role of FoxO Transcription Factors

2011 ◽  
Vol 43 (04) ◽  
pp. 268-274 ◽  
Author(s):  
M. Leyendecker ◽  
P. Korsten ◽  
R. Reinehr ◽  
B. Speckmann ◽  
D. Schmoll ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Rat Liver ◽  
Liver Cells ◽  
Rat Liver Cells ◽  
Foxo Transcription Factors

Bile salt excretion in skate liver is mediated by a functional analog of Bsep/Spgp, the bile salt export pump

2000 ◽  
Vol 278 (1) ◽  
pp. G57-G63 ◽  
Author(s):  
Nazzareno Ballatori ◽  
James F. Rebbeor ◽  
Gregory C. Connolly ◽  
David J. Seward ◽  
Benjamin E. Lenth ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Bile Salt ◽  
Rat Liver ◽  
Bile Salts ◽  
Plasma Membranes ◽  
Functional Characterization ◽  
Salt Transport ◽  
Positive Staining ◽  
Transport Activity ◽  
Canalicular Membrane

Biliary secretion of bile salts in mammals is mediated in part by the liver-specific ATP-dependent canalicular membrane protein Bsep/Spgp, a member of the ATP-binding cassette superfamily. We examined whether a similar transport activity exists in the liver of the evolutionarily primitive marine fish Raja erinacea, the little skate, which synthesizes mainly sulfated bile alcohols rather than bile salts. Western blot analysis of skate liver plasma membranes using antiserum raised against rat liver Bsep/Spgp demonstrated a dominant protein band with an apparent molecular mass of 210 kDa, a size larger than that in rat liver canalicular membranes, ∼160 kDa. Immunofluorescent localization with anti-Bsep/Spgp in isolated, polarized skate hepatocyte clusters revealed positive staining of the bile canaliculi, consistent with its selective apical localization in mammalian liver. Functional characterization of putative ATP-dependent canalicular bile salt transport activity was assessed in skate liver plasma membrane vesicles, with [3H]taurocholate as the substrate. [3H]taurocholate uptake into the vesicles was mediated by ATP-dependent and -independent mechanisms. The ATP-dependent component was saturable, with a Michaelis-Menten constant ( K m) for taurocholate of 40 ± 7 μM and a K m for ATP of 0.6 ± 0.1 mM, and was competitively inhibited by scymnol sulfate (inhibition constant of 23 μM), the major bile salt in skate bile. ATP-dependent uptake of taurocholate into vesicles was inhibited by known substrates and inhibitors of Bsep/Spgp, including other bile salts and bile salt derivatives, but not by inhibitors of the multidrug resistance protein-1 or the canalicular multidrug resistance-associated protein, indicating a distinct transport mechanism. These findings provide functional and structural evidence for a Bsep/Spgp-like protein in the canalicular membrane of the skate liver. This transporter is expressed early in vertebrate evolution and transports both bile salts and bile alcohols.

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