Micellar properties of sodium fusidate, a steroid antibiotic structurally resembling the bile salts

The properties of sodium fusidate micelles were determined by a spectral shift technique, surface tension measurements, and ultracentrifugal analysis. The critical micellar concentrations, mean molecular areas, and apparent aggregation numbers were estimated as a function of the concentration of counterion (0.001-1.0 m Na(+)) at 20 degrees C. The critical micellar concentrations were studied over a temperature range of 10 degrees C to 40 degrees C at one counterion concentration (0.001 m Na(+)), and from these data the standard thermo-dynamic functions of micellization were calculated. The ability of sodium fusidate solutions to solubilize the insoluble swelling amphiphiles, lecithin and monoolein, was investigated, and the results were compared with the solubilizing properties of sodium taurocholate. The critical micellar concentrations of sodium fusidate approximated those of sodium taurocholate. The values fell in the range of 1.44-4.56 mm, varying with the technique used, counterion concentration, and temperature. The percentage of counterions bound to fusidate micelles in water, calculated from the log critical micellar concentration-log Na(+) curve, was estimated to be negligible, which compares with sodium taurocholate micelles. The critical micellar concentration of sodium fusidate exhibited a minimum at 20 degrees C, a phenomenon observed with other ionic detergents and with bile salts. Micelle formation in sodium fusidate solutions was shown to be primarily entropy-driven at 10 degrees and 20 degrees C, whereas at 30 degrees and 40 degrees C the enthalpy factor predominated. From the surface tension measurements the molecular areas of sodium fusidate and sodium taurocholate were calculated. The mean molecular area of fusidate was 101 A(2), whereas sodium taurocholate possessed a molecular area of 88 A(2). It was demonstrated that the sodium fusidate molecule, like a bile salt molecule, lies with its longitudinal axis horizontal at an air-water interface. The apparent aggregation number of sodium fusidate micelles increased from 5 to 16 as the concentration of counterion increased from 0.01 to 0.60 m Na(+). These values are slightly larger than the corresponding aggregation numbers of sodium taurocholate micelles.     

Determination of the apparent functional molecular mass of the hepatocellular sodium-dependent taurocholate transporter by radiation inactivation

The apparent target size of the sodium-dependent taurocholate transporter in basolateral rat liver plasma membrane vesicles, showing overshooting taurocholate uptake in the presence of sodium was estimated by radiation inactivation. Radiation at -105 to -120 degrees C and 2.5 Mrad/min causes a dose-dependent monoexponential reduction of the overshoot of taurocholate uptake in the presence of sodium. In contrast, taurocholate transport in the absence of sodium and taurocholate permeation at 4 degrees C remained totally unaffected by the radiation dose, indicating that the passive permeability of the membrane towards taurocholate remained unaffected. Radiation inactivation by high-energy electrons provides information about the size of the functional unit of the transporter in situ. The target size determined represents the size of the radiation-sensitive mass which is compact enough for significant energy transfer to occur within all parts of the transport system. The minimal function molecular mass was determined to be 170 kDa for the sodium-dependent taurocholate transporter. To prove the validity of radiation inactivation data four internal standard enzymes were tested under identical conditions.     

In vitro excystation of Cryptosporidium baileyi from chickens

Release of sporozoites from the oocysts of Cryptosporidium baileyi is described from Nomarski interference-contrast microscopy. Just prior to excystation, the four sporozoites became motile and rearranged themselves within the oocyst. The sporozoites were then rapidly expelled through an opening that formed in the oocyst wall, and the residuum was either released or retained within the oocyst. Excysted sporozoites were crescent shaped and measured 5.0-9.0 microns X 1.0-1.6 micron (mean = 6.8 X 1.1 microns). Excystation occurred when sodium taurocholate or a mixture of trypsin and sodium taurocholate was present in the incubation medium. High levels of excystation occurred at 37 degrees or 40 degrees C, but excystation did not occur at 4 degrees C. The ability of biles from two avian and two mammalian hosts to produce excystation of C. baileyi was also studied. After a 2-h incubation at 40 degrees C, the percentages of excystation were 69.5% in goat bile, 45.0% in pig bile, 33.0% in chicken bile, and 34.5% in turkey bile.     

Solubilization and stabilization of human liver glycoprotein sialyltransferase.

Triton X-100 is increasingly effective in solubilizing human liver glycoprotein (asialofetuin) sialytransferase (CMP-N-acetylneuraminate:D-galactosyl-glycoprotien N-acetylneuraminyltransferase, EC 2.4.99.1) activity as its concentration is increased in the homogenizing buffer. At the optimal concentration of 1.5% (v/v), essentially all of the homogenate sialyltransferase activity was solubilized into the supernatant fluid. Higher concentrations of Triton X-100 inhibited sialyltransferase activity. Several kinetic properties of the solubilized asialofetuin-sialyltransferase activity were compared to those of the membrane-bound enzyme(s) (in homogenates made without Triton X-100 or in resuspended pellets). No major difference was apparent, suggesting that solubilization has not significantly altered the properties of sialyltransferase. The solubilized sialyltransferase activity is quite unstable, losing approximately 50% of its activity after one week of storage at 4 degrees C. Various detergents (Zwittergent, sodium taurocholate and sodium deoxycholate) are differentially effective in stabilizing the solubilized activity. Sodium taurocholate (1.5%, w/v) was most effective with no loss in activity after 40 days and minimal loss (14%) after 60 days storage at 4 degrees C. The solubilized sialyltransferase preparation retains full activity after storage in the frozen state (-20 degrees C) for at least 159 days.     

Thermodynamic and molecular determinants of sterol solubilities in bile salt micelles

We examined, by reverse-phase high performance liquid chromatography (HPLC), the hydrophilic-hydrophobic balance of cholesterol and 12 non-cholesterol sterols and related this property to their equilibrium micellar solubilities in sodium taurocholate and sodium glycodeoxycholate solutions. Sterols investigated exhibited structural variations in the polar function (3 alpha-OH, 3 beta-OH, 3 beta-SH), nuclear double bonds (none, delta 5, or delta 7), side chain length (C27, C28, C29) and side chain double bonds (none, delta 22, or delta 24). In general, a sterol's hydrophilic-hydrophobic balance became progressively more hydrophobic (as exemplified by increasing HPLC retention values, k') with additions of side chain methyl (C28) and ethyl (C29) groups and with 3 beta-SH substitution of the 3-OH polar function. Side chain delta 22 and especially delta 24 double bonds rendered the sterols appreciably more hydrophilic, whereas a single nuclear double bond had little influence. Sterol solubilities (24 degrees C, 0.15 M Na+) were uniformly greater in 50 mM solutions of sodium glycodeoxycholate (range 0.15 to 2.5 mM) than in equimolar solutions of the more hydrophilic bile salt, sodium taurocholate (range 0.07 to 0.67 mM). For each bile salt system, a strong inverse correlation existed between micellar solubilities of sterols and their HPLC k' values, indicating that more hydrophilic sterols had greater micellar solubilities than the more hydrophobic ones. Based upon the aqueous monomeric solubilities of cholesterol (C27) and beta-sitosterol (C29) at 24 degrees C, we derived free energy changes associated with micellar binding and found that solubilization of both sterols was more energetically favored in glycodeoxycholate solutions. Although cholesterol exhibited a higher binding affinity than beta-sitosterol in glycodeoxycholate micelles, solubilization of beta-sitosterol in taurocholate micelles was more energetically favored than cholesterol by -0.6 kcal/mol. Based upon these results we offer a thermodynamic explanation for the greater micellar solubilities of more hydrophilic sterols and suggest that the high affinity, but low capacity, of a typical phytosterol for binding to trihydroxy bile salt micelles may provide a physical-chemical basis for its inhibition of intestinal cholesterol absorption.     

Effect of various sodium taurocholate preparations on the recovery of Clostridium difficile spores

The effect of four sodium taurocholate preparations, which are easily available in Japan, on recovery of Clostridium difficile spores was examined. All preparations, except for one, enabled the recovery of nearly all spores counted microscopically. Moreover, by using 69 toxigenic and 34 nontoxigenic C. difficile strains, the relationship between the recovery of spores in the medium with sodium taurocholate and toxigenicity of C. difficile was analyzed. It was noted that the number of strains with recovery rate of more than 70% was greater in toxigenic strains than in nontoxigenic strains, suggesting a more abundant recovery of toxigenic C. difficile strains in the presence of sodium taurocholate.     

Solubilization of sphingomyelin vesicles by addition of a bile salt

The interactions of the bile salt sodium taurocholate (TC) in 50 mM Trizma-HCl buffer and 150 mM NaCl (pH 9) at 37 degrees C with membranes composed of sphingomyelin (SM) were studied by dynamic light scattering, cryogenic transmission electron microscopy (cryo-TEM) and turbidity measurements. Small unilamellar SM vesicles were prepared by extrusion. Below the CMC of TC, taurocholate addition leads to vesicle growth due to incorporation of the taurocholate molecules into the vesicle bilayer. At around half the CMC of the bile salt, the SM vesicles are transformed into SM/TC mixed worm-like micelles, which are visualized by cryo-TEM for the first time. Further increase in the taurocholate concentration leads to the rupture of these structures into small spherical micelles. Interestingly, large non-spherical micelles were also identified for pure taurocholate solutions. Similar threadlike structures have been reported earlier for the bile salt sodium taurodeoxycholate [Rich, A., Blow, D., 1958. Nature 182, 1777; Blow, D.M., Rich, A., 1960. J. Am. Chem. Soc. 82, 3566-3571; Galantini, L., Giglio, E., La Mesa, C., Viorel-Pavel, N., Punzo, F., 2002. Langmuir 18, 2812] and for mixtures of taurocholate and phosphatidylcholate [Ulmius, J., Lindblom, G., Wennerstr?m, H., Johansson, L.B.-A., Fontel, K., S?derman, O., Ardvisson, G., 1982. Biochemistry 21, 1553; Hjelm, R.P., Thiyagarajan, P., Alkan-Onyuksel, H., 1992. J. Phys. Chem. 96, 8653] as determined by various scattering methods.     

On the formation of calcium(II) taurocholate aggregate species in aqueous solution

Abstract

The influence of the presence of calcium(II) ions in solutions containing sodium and taurocholate ions at 25°C and in 0.5 mol dm^?3 N(CH₃)₄Cl as the constant ionic medium was studied. The composition and existence range of aggregates formed by taurocholate sodium and calcium(II) were investigated by means of two different procedures. First, the increasing calcium oxalate solubility due to the presence of taurocholate ions was studied as a function of the taurocholate, sodium and hydrogen ions. The free concentration of sodium and hydrogen ions was determined in solutions equilibrated with solid calcium(II) oxalate. After filtration, the concentration of calcium(II) (by atomic absorption spectro-photometry) and that of oxalate were also determined. In the second approach, electromotive force measurements carried out in solutions containing taurocholate, sodium and calcium(II) ions provided hydrogen and sodium ions free concentrations. The results from both procedures could be explained by assuming the presence of aggregates of different composition with the participation of sodium, calcium(II) and taurocholate ions, depending on the concentration of the reagents. No protonated species were present in appreciable concentrations. All the species found have even anion aggregation numbers. A strong analogy with the composition of sodium taurocholate and glycocholate is observed, while a comparison with sodium deoxycholate, glycodeoxycholate and taurodeoxycholate shows wide differences.     

Two distinct mechanisms for taurocholate uptake in subcellular fractions from rat liver

As part of the enterohepatic circulation, hepatocytes take up bile acids from the intestines via the hepatic portal blood using a sodium-dependent carrier mechanism and resecrete the bile acids into the bile. In order to assess whether intracellular organelles are involved in the transcellular secretion of bile acids, we measured directly the ability of purified subcellular fractions of rat liver to take up taurocholate using a Millipore filtration assay. Two distinct uptake mechanisms can be discerned, one localized in the plasma membranes and the other in the Golgi and smooth microsomal fractions. Plasma membranes prepared by the method of Fleischer and Kervina (Fleischer, S., and Kervina, M. (1974) Methods Enzymol. 31, 6) take up taurocholate in a saturable manner with an apparent Vmax of 2.4 nmol min-1 mg protein-1 and a Km of 190 microM at 37 degrees C. After preincubation of the membranes with K+ ions, a sodium gradient (100 mM outside) stimulates the uptake rate by 90% with the observed Km unchanged. The stimulation is inhibited by phalloidin but not by bromosulfophthalein. Bile canalicular plasma membranes made according to Kramer et al. (Kramer, W., Bickel, U., Buscher, H. P., Gerok, W., and Kurz, G. (1982) Eur. J. Biochem. 129, 13-24) do not take up taurocholate. The transport by Golgi vesicles and smooth microsomes differs from that in the plasma membrane fraction in that it is not stimulated by a sodium gradient, has a Vmax of 12 nmol min-1 mg protein-1 and a Km of 440 microM at 37 degrees C, and is inhibited by bromosulfophthalein but not by phalloidin. Taurocholate uptake into smooth microsomes is abolished by filipin, an antibiotic that complexes with cholesterol to disrupt the membrane. This suggests that taurocholate uptake occurs into a nonendoplasmic reticulum subfraction since endoplasmic reticulum membranes contain negligible amounts of cholesterol. Little uptake was observed using rough microsomes or mitochondria. A model of transhepatic transport compatible with our observations is that taurocholate uptake into the cytoplasm occurs via the plasma membranes on the sinusoidal side of the hepatocyte; taurocholate is then taken up into smooth vesicles and the Golgi complex and is secreted into the bile by exocytosis as the vesicles fuse with the canalicular plasma membranes.     

Niemann-Pick disease, Type C: evidence for the deficiency of an activating factor stimulating sphingomyelin and glucocerebroside degradation

1) Qualitative lipid analyses by thin-layer chromatography of 4 Niemann-Pick type C spleens confirmed sphingomyelin accumulation together with increase in the amount of glucocerebroside. 2) In the presence of crude sodium taurocholate as detergent, sphingomyelin degradation rates of normal and Niemann-Pick type C-cultured fibroblasts were fairly close under standard conditions at pH 5.0. In the absence of sodium taurocholate, sphingomyelinase activity was optimal at pH 4.0. Sphingomyelinase activities of fibroblasts from two patients with Niemann-Pick disease type C measured without detergent, were about 30% of that of controls. 3) Extracts from Gaucher spleen heated to 90 degrees C and devoid of sphingomyelinase activity stimulated at the optimal pH of 4.0 sphingomyelin degradation by cultured normal fibroblasts (2--4-fold, Niemann-Pick type C fibroblasts (5--9-fold), whereas similarly treated extracts from Niemann-Pick type C spleen showed no stimulation of sphingomyelin catabolism. Heated extracts from normal human spleen exhibited a smaller stimulation than that shown by Gaucher spleen. This stimulating effect could not be observed in fibroblasts from patients suffering from Niemann-Pick type B (sphingomyelinase defect). 4) Heat-treated extracts of Gaucher spleen were fractionated by ion exchange chromatography, isoelectric focusing and gel filtration. The active fractions obtained by these procedures stimulated sphingomyelin as well as glucocerebroside degradation and were absent from the corresponding Niemann-Pick type C preparations. Enriched activator preparations of Gaucher spleen stimulated sphingomyelinase activity of Niemann-Pick type C fibroblasts 25--38-fold and that of normal cells 3-fold. 5) The activating factor had an isoelectric point of 4.0 and an apparent molecular weight, as estimated by gel filtration, of 25000. Treatment with pronase E abolished its activity.     

The utilization of sodium taurocholate in excystation of Cryptosporidium parvum and infection of tissue culture.

The present work deals with optimization of excystation of Cryptosporidium parvum oocysts and the infection process of tissue culture cells by the parasite. It was shown that presence of the bile salt sodium taurocholate in the incubation medium expedited excystation of the tested GCH1 isolate and enhanced it, as compared with bleaching of the oocysts. This bile salt had no effect on the viability of tissue culture cell lines MDBK and HCT-8 at the tested concentration of 0.375% for up to 2 hr of coincubation. Infection studies conducted on tissue culture cells showed higher infection rates in the presence of sodium taurocholate than with bleached oocysts in the absence of this bile salt. It may be concluded that, at least as regards the GCH1 strain of C. parvum, the whole infection process can be performed in the presence of sodium taurocholate, and does not require separation and cleaning of the excysted sporozoites before their application to tissue culture cells.     

乳杆菌耐胆汁、降解结合胆盐和同化胆固醇能力的研究

对8株植物乳杆菌的胆汁耐受力、降解结合胆盐能力以及同化胆固醇能力进行了研究。不同的菌株在添加了牛胆汁的MRS中生长速度具有明显差异,同化胆固醇能力也明显不同,而降解结合胆盐的能力没有明显区别。分析发现,菌株的胆汁耐受力和降解结合胆盐能力,胆汁耐受力和同化胆固醇能力,以及降解结合胆盐能力和同化胆固醇能力之间都没有明显的相关性。     

Biochemical site of regulation of bile acid biosynthesis in the rat

The production of bile salts by rat liver is regulated by a feedback mechanism, but it is not known which enzyme controls endogenous bile acid synthesis. In order to demonstrate the biochemical site of this control mechanism, bile fistula rats were infused intravenously with (14)C-labeled bile acid precursors, and bile acid biosynthesis was inhibited as required by intraduodenal infusion of sodium taurocholate. The infusion of taurocholate (11-14 mg/100 g of rat per hr) inhibited the incorporation of acetate-1-(14)C, mevalonolactone-2-(14)C, and cholesterol-4-(14)C into bile acids by approximately 90%. In contrast, the incorporation of 7alpha-hydroxycholesterol-4-(14)C into bile acids was reduced by less than 10% during taurocholate infusion. These results indicate that the regulation of bile acid biosynthesis is exerted via cholesterol 7alpha-hydroxylase provided that hepatic cholesterol synthesis is adequate.     

Sodium-dependent taurocholate uptake by isolated rat hepatocytes occurs through an electrogenic mechanism

The uptake mechanism for the bile salt, taurocholate, by the liver cell is coupled to sodium but the stoichiometry is controversial. A one-to-one coupling ratio would result in electroneutral transport, whereas cotransport of more than one sodium ion with each taurocholate molecule cause an electrogenic response. To better define the uptake of this bile salt, we measured the effect of taurocholate on the membrane potential and resistance of isolated rat hepatocytes using conventional microelectrode electrophysiology. The addition of 20 microM taurocholate caused transient but significant depolarization accompanied by a significant decrease in membrane resistance. The electrical effect induced by taurocholate mimicked that induced by L-alanine (10 mM), the uptake of which is known to occur through an electrogenic, sodium-coupled mechanism. The sodium dependence of taurocholate-induced depolarization was further confirmed by: (1) replacing Na+ with choline +, and (2) preincubating cells with ouabain (2 mM) or with the Na+-ionophore, gramicidin (25 micrograms/ml); both suppressed the electrogenic response. Further, cholic acid, which inhibits sodium-coupled taurocholate uptake in hepatocytes, inhibited taurocholate evoked depolarization. These results support the hypothesis that sodium-coupled taurocholate uptake by isolated hepatocytes occurs through an electrogenic process which transports more than one Na+ with each taurocholate molecule.     

Effect of sodium taurocholate and sodium cholate on short-circuit current on amphibian membranes

The effects of the bile salts, sodium taurocholate (NaTc) and sodium cholate (NaCh), and toad bile gallbladder (bile) on short-circuit current (SCC) across isolated skin, and sodium taurocholate (NaTc) on isolated bladder of Bufo arenarum toads were tested. Sodium taurocholate (NaTc), sodium cholate (NaCh) and toad bile gallbladder (bile) promoted an increase in SCC, when added to the external side. The stimulatory effect was reversible after rinsing the preparation for 60 min. Implications on in vivo renal function of these results are discussed.     

The influence of (3H)taurocholate on the biliary excretion of (14C)acetylprocaine amide ethobromide.

The biliary excretion rates of [14C]acetylprocaine amide ethobromide (acetyl-PAEB) and [3H]taurocholate, either administered alone or in combination to adult male Wistar rats, were studied. Their renal pedicles were ligated, and the common bile duct and one jugular vein cannulated. Acetyl-PAEB, 20 mg/kg, and sodium taurocholate, 70 mg/kg, were infused over a 5-min period. Blood and bile samples were collected every 10 min for 60 min. Liver samples were taken at 10 and 20 min. Approximately 100% of the administered taurocholate was excreted within 50 min. The simultaneous administration of acetyl-PAEB did not significantly alter the taurocholate excretion. The amount of the acetyl-PAEB dose excreted in 1 h was 9.4%. This was increased significantly to 16.5% when taurocholate was given concomitantly. The concentration of acetyl-PAEB in the bile increased significantly when taurocholate was given, and the ratios of its concentrations in bile-liver and bile-plasma were also increased. Taurocholate did not alter the liver-plasma concentration ratio of acetyl-PAEB. It is suggested that the concomitant administration of taurocholate increased the biliary excretion of acetyl-PAEB by facilitating its secretion by the liver into the bile.     

Shedding of sulfated lipids into gastric fluid and inhibition of pancreatic DNase I by cholesterol sulfate in concert with bile acids

Cholesterol sulfate (CS) and sulfatides in the epithelium of the digestive tract were found in the 1000xg supernatants of digestive fluid, particularly in gastric juices containing the duodenal contents and bile acids, there being 14-131 microg of CS and 3-54 microg of sulfatides per mg of protein in the fluid, respectively. CS and sulfatides dissolved in detergents including bile acids inactivated pancreatic trypsin to the same level as by DMSO-solubilized sulfated lipids at 37 degrees C. Similarly, pancreatic DNase I was inhibited by CS solubilized with DMSO or bile acids, but not by sulfatides or other membrane lipids at 37 degrees C. Both the sulfate group and the hydrophobic side chain of CS were indispensable structures for the inhibition of DNase I. Also, the optimum molar ratio of bile acids to CS was important for expression of the inhibitory activity of CS toward DNase I, it being 0.18 of the optimum ratio for sodium taurocholate, and the molar ratio of CS to DNase I for complete inhibition was 342:1. Thus, CS was shown to play a role as an epithelial inhibitor of DNase I in concert with bile acids.     

HEMOLYSIS OF CHICKEN BLOOD

1. The time-dilution curves are given for the hemolytic action of saponin, sodium taurocholate, and sodium oleate on nucleated chicken erythrocytes. 2. Saponin and sodium taurocholate cause hemolysis but leave the nuclei and ghosts in suspension, thereby making the end-point of hemolysis more arbitrary than the clear end-point for non-nucleated cell hemolysis. 3. The curves of hemolysis by saponin and taurocholate are shown to be of the same nature as are found in the hemolysis of non-nucleated cells. 4. Sodium oleate causes first hemolysis and then, in the stronger solutions, causes karyolysis. Two pairs of values for κ and c = ∞ are thus obtainable for the same reaction, one pair for the destruction of corpuscular membrane, the other pair for the destruction of the nucleus. 5. Viscosity changes are found in the lysin-cell system with strong concentrations of sodium taurocholate and sodium oleate. Time-viscosity curves are given for these changes. 6. Microscopically, the action of these lysins on the nucleated chicken red cell appears to be similar to their action on the non-nucleated erythrocytes.     

Studies on Lipase from Candida cylindracea

Lipase from Candida cylindracea has been purified by ammonium sulfate precipitation, sodium deoxycholate treatment, ethanol-ether precipitation and chromatography on SE-Sephadex and Sephadex G-100 columns. The purification of the enzyme was 33.4-fold with a yeild of 18.0% on the basis of activity per weight of protein. The purified enzyme was homogeneous on ultracentrifugation and electrophoresis. Optimum pH for the hydrolysis of olive oil was 7.2 by the assay method using a polyvinylalcohol-emulsified system and 5.2 by the assay method using a shaken system without a macromolecular emulsifier. Optimum temperature was 45°C. The enzyme was stable up to 15°G and in the range of pH from 2.0 to 8.5. Sodium taurocholate showed either an activating or an inhibiting effect at pH 7.0, depending on the sodium taurocholate concentration and on the assay system.     

Bile salt related secretion of acid phosphatase in rat bile

The biliary excretion of bile salts, lysosomal acid phosphatase, and total proteins were studied in rats under different experimental conditions: during bile salt loss through a bile fistula and after loading with exogenous sodium taurocholate. The experimental models were suitable to demonstrate that variations in the excretion of bile salts were associated with those of acid phosphatase output. During bile salt depletion, acid phosphatase output showed a decrease parallel to that of bile salts. Following a single i.v. injection of sodium taurocholate and during its i.v. infusion, a rapid increase of acid phosphatase excretion in bile was seen. The patterns of enzyme outputs observed after administration of sodium taurocholate suggested a bulk discharge in bile of lysosomal contents. The profiles of protein output were similar to those of acid phosphatase suggesting an association between the secretory mechanism of these bile constituents. In contrast to sodium taurocholate, 4-methylumbelliferone, which also increases canalicular bile flow, did not produce changes in the excretory patterns of the bile components studied. Therefore, the results suggested a bile salt related secretion of acid phosphatase in the rat, which may involve protein secretion in bile.