scholarly journals Biliary protein output by isolated perfused rat livers. Effects of bile salts

1983 ◽  
Vol 210 (2) ◽  
pp. 549-557 ◽  
Author(s):  
S G Barnwell ◽  
P P Godfrey ◽  
P J Lowe ◽  
R Coleman
Keyword(s):  
Plasma Membrane ◽  
Bile Salt ◽  
Bile Salts ◽  
Serum Proteins ◽  
Critical Micellar Concentration ◽  
Rapid Decline ◽  
Perfusion Medium ◽  
Rat Serum ◽  
Membrane Enzymes ◽  
Rat Livers

The output of proteins into bile was studied by using isolated perfused rat livers. Replacement of rat blood with defined perfusion media deprived the liver of rat serum proteins (albumin, immunoglobulin A) and resulted in a rapid decline in the amounts of these proteins in bile. When bovine serum albumin was incorporated into the perfusion medium it appeared in bile within 20 min and the amount in the bile was determined by the concentration of the protein in the perfusion medium. The use of a defined perfusion medium also deprived the livers of bile salts and the amounts of these, and of plasma-membrane enzymes [5′-nucleotidase (EC 3.1.3.5) and phosphodiesterase I], in bile declined rapidly. Introduction of micelle-forming bile salts (taurocholate or glycodeoxycholate) to the perfusion medium 80 min after liver isolation markedly increased the output of plasma-membrane enzymes but had no effect on the other proteins. The magnitude of this response was dependent on the bile salt used and its concentration in bile; there was little effect on plasma-membrane enzyme output until the critical micellar concentration of the bile salt had been exceeded in the bile. A bile salt analogue, taurodehydrocholate, which does not form micelles, did not produce the enhanced output of plasma-membrane enzymes. This work supports the view that the output of plasma-membrane enzymes in bile is a consequence of bile salt output and also provides evidence for mechanisms by which serum proteins enter the bile.

scholarly journals Effect of taurochenodeoxycholate or tauroursodeoxycholate upon biliary output of phospholipids and plasma-membrane enzymes, and the extent of cell damage, in isolated perfused rat livers

1983 ◽  
Vol 216 (1) ◽  
pp. 107-111 ◽  
Author(s):  
S G Barnwell ◽  
P J Lowe ◽  
R Coleman
Keyword(s):  
Plasma Membrane ◽  
Bile Salt ◽  
Bile Flow ◽  
Bile Salts ◽  
Cell Damage ◽  
Characteristic Difference ◽  
Membrane Enzymes ◽  
Hepatobiliary System ◽  
Rat Livers

Isolated perfused rat livers were used to study the effects of taurochenodeoxycholate (TCDC) and tauroursodeoxycholate (TUDC) upon some aspects of biliary composition. After depletion of the endogenous bile salt pool of the liver, introduction of either bile salt brought about increases in bile flow, bile salt output and biliary phospholipid output. Taurochenodeoxycholate needed a lower biliary concentration to produce phospholipid output than did tauroursodeoxycholate. TCDC perfusion caused a substantial output of plasma-membrane enzymes (5′-nucleotidase and alkaline phosphodiesterase) into the bile, whereas TUDC caused little output of either enzyme; this may represent a characteristic difference between the effects of the two bile salts on the hepatobiliary system. The results from TUDC perfusion indicate also that much of the output of biliary phospholipid promoted by bile salts, may be independent of the output of plasma-membrane enzymes promoted by bile salts.

scholarly journals The effects of colchicine on secretion into bile of bile salts, phospholipids, cholesterol and plasma membrane enzymes: bile salts are secreted unaccompanied by phospholipids and cholesterol

1984 ◽  
Vol 220 (3) ◽  
pp. 723-731 ◽  
Author(s):  
S G Barnwell ◽  
P J Lowe ◽  
R Coleman
Keyword(s):  
Plasma Membrane ◽  
Protective Effect ◽  
Bile Salt ◽  
Aspartate Aminotransferase ◽  
Bile Salts ◽  
Membrane Damage ◽  
Aminotransferase Activity ◽  
Canalicular Membrane ◽  
Membrane Enzymes ◽  
Taurocholate Transport

Colchicine, a drug which interferes with microtubular function, has no effect on the secretion of taurodehydrocholate into bile; it is therefore suggested that bile salts are unlikely to be packaged in vesicles during cellular transit from sinusoidal to canalicular membranes. Colchicine greatly reduces the secretion of phospholipid and cholesterol into bile; it is suggested that this is due to an interruption in the supply of vesicles bringing lipids to repair the canalicular membrane during bile salt output. In the absence of the protective effect of a continuous supply of repair vesicles, micelleforming bile salts damage the canalicular membrane; the increased concentration of plasma membrane enzymes in bile and the increased aspartate aminotransferase activity in plasma and bile are evidence of this damage. Damage to the canalicular membrane may also be an explanation for the reduction in taurocholate transport and the taurocholate-induced cholestasis which are seen with colchicine-treated livers. Such membrane damage is not observed in colchicine-treated livers during the secretion of the non-micelle forming bile salt, taurodehydrocholate.

scholarly journals Enzymes and proteins in bile Variations in output in rat cannula bile during and after depletion of the bile-salt pool

1981 ◽  
Vol 196 (1) ◽  
pp. 11-16 ◽  
Author(s):  
P P Godfrey ◽  
M J Warner ◽  
R Coleman
Keyword(s):  
Plasma Membrane ◽  
Acid Phosphatase ◽  
Bile Salt ◽  
Bile Salts ◽  
Lysosomal Enzymes ◽  
Protein Concentration ◽  
Enterohepatic Circulation ◽  
Cell Damage ◽  
Membrane Enzymes ◽  
Rat Bile

The protein concentration in bile from several species is reported. The changes in output of protein, bile salts and several enzymes have been followed in rat bile over a 48 h cannulation period. Bile-salt concentration dropped rapidly owing to interruption of the enterohepatic circulation but the output of protein, lysosomal enzymes [acid phosphatase (EC 3.1.3.2) and beta-D-glucuronidase (EC 3.2.1.31)] and plasma-membrane enzymes [5′-nucleotidase (EC 3.1.3.5) and phosphodiesterase I (EC 3.1.4.1)] was maintained. Liver cell damage, monitored by output of lactate dehydrogenase, was very low throughout. Protein, lysosomal enzymes and plasma-membrane enzymes showed different patterns of output with time, but all showed a net increase between 12 and 24 h. The output of lysosomal and plasma-membrane enzymes was between 1 and 5% of the total liver complement over the first 24 h; if inhibition by biliary components is taken into account the output of some of these enzymes, particularly acid phosphatase, may be greater. Ultracentrifugation of bile showed that as the concentration of bile salts decreases the proportion of plasma-membrane enzymes in a sedimentable form increases. The results are discussed in relation to other studies of biliary proteins and to studies of the perturbation of membranes and cells with bile salts.

scholarly journals Rapid kinetic analysis of the bile-salt-dependent secretion of phospholipid, cholesterol and a plasma-membrane enzyme into bile

1984 ◽  
Vol 222 (3) ◽  
pp. 631-637 ◽  
Author(s):  
P J Lowe ◽  
S G Barnwell ◽  
R Coleman
Keyword(s):  
Plasma Membrane ◽  
Bile Salt ◽  
Kinetic Analysis ◽  
Bile Salts ◽  
Mixed Micelles ◽  
Biliary Lipid ◽  
Vesicle Traffic ◽  
Membrane Enzyme ◽  
Rat Livers ◽  
Isolated Rat

Isolated rat livers were perfused under ‘one-pass’ conditions and bile was collected at 1 min intervals. After 1 min pulse, taurocholate appeared in the collected bile within 2 min, peak output occurring 2 min later. In contrast, the increased output of phospholipids and cholesterol was slower, peak output occurring 6-11 min after the original pulse of taurocholate. These results suggest that mixed micelles cannot be formed inside the cell or during passage of bile salts through the membrane, since bile salt and lipids should then parallel each other. The bile salts must therefore be pumped into the lumen and the lipids added subsequently, due to the actions of the bile salts in the canalicular lumen. It is suggested that the biliary lipid is obtained from microdomains of biliary-type lipid in the canaliculus membrane, which are vesiculated and solubilized by the action of bile salts. It is also suggested that this biliary-type lipid is brought continuously to the membrane via vesicle traffic; this traffic is increased during increased bile-salt output, and is a process that can be inhibited by colchicine.

Hepatic bile flow

1984 ◽  
Vol 64 (4) ◽  
pp. 1055-1102 ◽  
Author(s):  
R. C. Strange
Keyword(s):  
Bile Salt ◽  
Bile Salts ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Critical Micellar Concentration ◽  
Canalicular Membrane ◽  
Receptor Proteins ◽  
Subcellular Organelles ◽  
Golgi Bodies ◽  
Initial Event

The hepatocyte is a polar cell that can remove a variety of molecules from blood and excrete them into bile. This review is primarily concerned with the mechanism of transport of the principal anions--the bile salts--across the sinusoidal membrane, their passage through the cell, and excretion across the canalicular membrane. Clearly much of this process is poorly understood, but the study of the membrane stages should be facilitated by the ability to prepare purified sinusoidal and canalicular membrane vesicles. For example, the relative importance of albumin-binding sites as well as the putative bile salt receptor proteins can be better assessed. It seems likely that although the interaction of bile salts with receptor proteins is important, it is an initial event that puts the bile salt in the correct place for uptake to occur. The driving force for uptake is the Na+ gradient created across the basolateral membrane by the activity of the Na+-K+-ATPase. Within the cell, various modes of transport have been suggested. Several authors emphasize the importance of protein binding of bile salts, either because of their presumed ability to maintain the concentration of these anions in the hepatocyte below their critical micellar concentration or because of their putative role in transport. It is important to understand these aspects of the role of cytosolic proteins for several reasons. Knowledge of the true concentration of free bile salt within the cell should allow estimation of whether the electrochemical gradient is sufficient for bile salts to accumulate in bile without the need for active transport of molecules from the cell into the canaliculus. The compartmental model described by Strange et al. (153) offers one theoretical way of determining the concentration of free bile salt, although the problems inherent in studying amphipath binding to the membranes of subcellular organelles (31) require that the model be reevaluated by the hygroscopic-desorption method. The second role suggested for the cytosolic bile salt-binding proteins is as transport proteins. As discussed in section VI, I think it is unlikely that the proteins identified so far act in this way, and it is more likely that movement occurs by diffusion in free solution. It is also important to determine the possible involvement of subcellular organelles such as Golgi bodies. Little is known of their role in the transport of bile salts or indeed where bile salt micelles are formed.(ABSTRACT TRUNCATED AT 400 WORDS)

The Effects of Bile Salts on Some Coagulation Components and Related Enzymes

1972 ◽  
Vol 27 (03) ◽  
pp. 594-609 ◽  
Author(s):  
A. M Engel ◽  
B Alexander
Keyword(s):  
Platelet Aggregation ◽  
Bile Salt ◽  
Salt Concentration ◽  
Bile Salts ◽  
Direct Action ◽  
Critical Micellar Concentration ◽  
The Other ◽  
Salt Mixture ◽  
Induced Aggregation ◽  
Activator Complex

SummaryCertain purified bile salts, individually or in a mixture, profoundly affect - either inhibiting or enhancing - the esterolytic activities of thrombin, trypsin, and plasmin, the clotting activity of thrombin, and caseinolysis by trypsin. They also promote SK-induced fibrinolysis and impair FI clottability. These effects are directly related to bile salt concentration but not to the critical micellar concentration.A very unusual effect was observed with deoxycholate and FI : besides inhibiting FI clottability, the salt induces spontaneous gelation. In addition, it binds strongly to the protein, as has been already reported for another plasma protein, albumin, and to a lesser degree, to alpha- and beta-globulins.Noteworthy is the fact that activation of pancreatic juice trypsinogen by thrombin also was increased by prior thrombin exposure to the salts. On the other hand, thrombin-induced platelet aggregation was slightly inhibited by the bile salt mixture, which, when added to PRP moderately inhibited the ADP-induced aggregation. No effect was observed on the conversion of F II in plasma via the thromboplastic mechanism when deoxycholate, or cholate, or glycocholate was added to the system.It is postulated that the bile salt mixture enhances SK-induced fibrinolysis by direct action, either on SK, or on the SK-activator complex, attributable to the detergent properties of the salts.The physiologic and pathologic implications of our results with respect to hemostasis and pancreatitis are discussed.

scholarly journals Spectrophotometric determination of the critical micellar concentration of bile salts using bilirubin monoglucuronide as a micellar probe. Utility of derivative spectroscopy

1988 ◽  
Vol 252 (1) ◽  
pp. 275-281 ◽  
Author(s):  
W Spivak ◽  
C Morrison ◽  
D Devinuto ◽  
W Yuey
Keyword(s):  
Bile Salt ◽  
Bile Salts ◽  
Sodium Taurocholate ◽  
Critical Micellar Concentration ◽  
Relative Energy ◽  
Bile Pigment ◽  
Sharp Change ◽  
Derivative Spectroscopy ◽  
Invasive Method ◽  
Sudden Decrease

We have developed a simple biologically non-invasive method for determining the critical micellar concentration (CMC) of bile salts using pure naturally occurring bilirubin IX alpha monoglucuronide (BMG), an important bile pigment present in virtually all mammalian biles. This methodology employs visible absorbance spectroscopy of BMG in bile salts over a range of bile salt concentrations that include the reported CMC. Using 100 microM-BMG in 0.4 M-imidazole buffer at pH 7.8, we calculated that the CMC for sodium taurochenodeoxycholate is between 2.5 and 3.0 mM based on: (1) an abrupt change in lambda max. in this concentration range, (2) a precipitous decrease in the amplitude of the absorbance shoulder at 450 nm, (3) a sudden decrease in the second derivative absorbance of BMG at 400 nm and an increase in absorbance at 470 nm, (4) a sharp change in the 4th derivative absorbance at 375 and 395 nm. In contrast, sodium taurocholate, a bile salt that reportedly does not have a CMC but continuously self-associates over a wide concentration range, exhibited none of these changes. The use of derivative spectroscopy enhances the ability to detect the CMC changes and also indicates the number of BMG species in solution and their relative energy states.

scholarly journals Self-association of unconjugated bilirubin-IX α in aqueous solution at pH 10.0 and physical-chemical interactions with bile salt monomers and micelles

1979 ◽  
Vol 179 (3) ◽  
pp. 675-689 ◽  
Author(s):  
M C Carey ◽  
A P Koretsky
Keyword(s):  
Aqueous Solution ◽  
Absorption Spectrum ◽  
Bile Salt ◽  
Bile Salts ◽  
Sodium Dodecyl ◽  
Chemical Properties ◽  
Critical Micellar Concentration ◽  
Solvent Mixtures ◽  
Physical Chemical ◽  
Self Association

Spectrophotometric measurements of bilirubin-IX alpha in water and in aqueous/organic solvent mixtures at pH 10.0 as a function of bilirubin-IX alpha concentration (approx. 0.6–400 microM) are consistent with the formation of dimers (KD - 1.5 microM) in dilute (less than 10 microM) aqueous solution and further self-aggregation to multimers at higher concentrations. Added urea (to 10M) and increases in temperature (to 62 degrees C) obliterate the dimer-multimer transition at 10 microM, but added NaCl (to 0.30 M) promotes strong aggregation of dimers over a narrow concentration range, suggesting a ‘micellization’ phenomenon. Concentrations of dioxan or ethanol greater than 60% (v/v) in water were required to obtain the absorption spectrum of bilirubin-IX alpha monomers, suggesting that both hydrophobic and electrostatic (pi-orbital) interactions are involved in stabilizing the dimeric state in water. Micellar concentrations of sodium dodecyl sulphate induced spectrophotometric shifts in the dimer absorption spectrum of bilirubin-IX alpha consistent with progressive partitioning of bilirubin-IX alpha monomers into a relatively non-polar region of the micelles and allowed a deduction of the apparent critical micellar concentration that closely approximated the literature values. The pattern of bilirubin IX alpha association with bile salts is complex, since the absorption spectrum shifts hypsochromically below and bathochromically above the critical micellar concentration of the bile salts. Consistent with these observations, bilirubin IX alpha appears to bind to the polar face of bile salt monomers and to the polar perimeter of small bile salt micelles. At higher bile salt concentrations some-bilirubin-IX alpha monomers partition into the hydrophobic interior of the bile salt micelles. Our results suggest that under physiological conditions the natural conjugates of bilirubin-IX alpha may exhibit similar physical chemical properties in bile, in that dimers, highly aggregated multimers and bile salt-associated monomers may co-exist.

Effect of bile salt on phosphatidylcholine composition and secretion of hepatic high-density lipoproteins

1990 ◽  
Vol 259 (2) ◽  
pp. G205-G211 ◽  
Author(s):  
S. J. Robins ◽  
J. M. Fasulo ◽  
G. M. Patton
Keyword(s):  
Bile Salt ◽  
Molecular Species ◽  
Bile Salts ◽  
Low Density Lipoproteins ◽  
High Density ◽  
High Density Lipoproteins ◽  
Absolute Amount ◽  
Very Low Density Lipoproteins ◽  
Rat Livers ◽  
Isolated Rat

Bile salts are necessary for the secretion of phosphatidylcholines (PCs) in bile and result in the selective secretion of highly hydrophilic molecular species of PC that contain a 16:0 acyl group. To determine the effect of bile salt on the secretion of PCs in lipoproteins, isolated rat livers were perfused with and without taurocholate. The PC composition of very-low-density lipoproteins (VLDL), newly synthesized by the liver, precisely mirrored the composition of PCs in the whole liver and was not changed with the administration of taurocholate. In contrast, both the composition of PCs in high-density lipoproteins (HDL) and the absolute amount of newly synthesized HDL were markedly affected by the administration of taurocholate. With taurocholate the PC content of HDL was increased, HDL was enriched, like bile, in 16:0 molecular species of PC, and the amount of HDL that was recovered in the perfusate was 2.5-fold greater than without taurocholate (P less than 0.001). These findings suggest that VLDL and HDL are differently derived from within the liver, that the PCs of HDL and bile originate from the same hepatic pool or by the same mechanism, and that both the secretion of bile and HDL from the liver are susceptible to regulation by bile salt.

Molecular mechanisms of hepatic bile salt transport from sinusoidal blood into bile

1995 ◽  
Vol 269 (6) ◽  
pp. G801-G812 ◽  
Author(s):  
P. J. Meier
Keyword(s):  
Plasma Membrane ◽  
Bile Salt ◽  
Bile Salts ◽  
Organic Anion ◽  
Salt Transport ◽  
Salt Flux ◽  
Salt Uptake ◽  
Canalicular Bile ◽  
Salt Secretion ◽  
Bile Salt Transport

An increasingly complex picture has emerged in recent years regarding the bile salt transport polarity of hepatocytes. At the sinusoidal (or basolateral) plasma membrane two bile salt-transporting polypeptides have been cloned. The Na(+)-taurocholate-cotransporting polypeptide (Ntcp) can account for most, if not all, physiological properties of the Na(+)-dependent bile salt uptake function in mammalian hepatocytes. The cloned organic anion-transporting protein (Oatp1) can mediate Na(+)-independent transport of bile salts, sulfobromophthalein, estrogen conjugates, and a variety of other amphipathic cholephilic compounds. Hence, Oatp1 appears to correspond to the previously suggested basolateral multispecific bile sale transporter. Intracellular bile salt transport can be mediated by different pathways. Under basal bile salt flux conditions, conjugated trihydroxy bile salts bind to cytoplasmic binding proteins and reach the canalicular plasma membrane predominantly via cytoplasmic diffusion. More hydrophobic mono- and dihydroxy and high concentrations of trihydroxy bile salts associate with intracellular membrane-bound compartments, including transcytotic vesicles, endoplasmic reticulum (ER), and Golgi complex. A facilitated bile salt diffusion pathway has been demonstrated in the ER. The exact role of these and other (e.g., lysosomes, "tubulovesicular structures") organelles in overall vectorial transport of bile salts across hepatocytes is not yet known. Canalicular bile salt secretion is mediated by two ATP-dependent transport systems, one for monovalent bile salts and the second for divalent sulfated or glucuronidated bile salt conjugates. The latter is identical with the canalicular multispecific organic anion transporter, which also transports other divalent organic anions, such as glutathione S-conjugates. Potential dependent canalicular bile salt secretion has also been suggested to occur, but its exact mechanism and physiological significance remain unclear, since a potential driven bile salt uptake system has also been identified in the ER. Hypothetically, and similar to changes in cell volume, the intracellular potential could also play a role in the regulation of the number of bile salt carriers at the canalicular membrane and thereby indirectly influence the maximal canalicular bile salt transport capacity of hepatocytes.

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