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PubMed2001

The optical interconversion of the P-450 and P-420 forms of neuronal nitric oxide synthase: effects of sodium cholate, mercury chloride and urea.

We investigated whether or not neuronal nitric oxide synthase (nNOS) (EC 1.14.13.39) was converted to the P-420 form on exposure to sodium cholate, mercury chloride or urea, and the reconversion of the P-420 to the P-450 form. Sodium cholate and mercury chloride induced the conversion of nNOS from the P-450 to the P-420 form in concentration- and incubation time-dependent manners, and the nNOS activity decreased. In the presence of glycerol, L-arginine and/or tetrahydrobiopterin, the sodium cholate-treated P-420 form could be reconverted to the P-450 form under constant experimental conditions, and the nNOS activity could also be restored. The mercury chloride-treated P-420 form of nNOS could be reconverted to the P-450 form on incubation with reduced glutathione (GSH) or L-cysteine, and the nNOS activity was recovered. However, no reconversion of the mercury chloride-treated P-420 form to the P-450 form was observed in the presence of glycerol, L-arginine, or tetrahydrobiopterin. Urea (4.0 M) dissociated nNOS into its subunits, but nNOS remained in the P-450 form. The nNOS monomer was more susceptible to sodium cholate. After removing the urea by dialysis, and supplementation of the nNOS solution with glycerol, L-arginine or BH(4), the P-420 was reconverted to the P-450 form, and the reassociation of nNOS monomers was also observed. These results suggested that nNOS was more stable as to exposure to sodium cholate, mercury chloride or urea in comparison to microsomal cytochrome P-450, which may be due to the different heme environment and protein structure.

Animals↗
PubMed2003

Cholesterol and cholate components of an atherogenic diet induce distinct stages of hepatic inflammatory gene expression.

Atherosclerosis in inbred mouse strains has been widely studied by using an atherogenic (Ath) diet containing cholesterol, cholic acid, and fat, but the effect of these components on gene expression has not been systematically examined. We employed DNA microarrays to interrogate gene expression levels in liver of C57BL/6J mice fed the following five diets: mouse chow, the Ath diet, or modified versions of the Ath diet in which either cholesterol, cholate, or fat were omitted. Dietary cholesterol and cholate produced discrete gene expression patterns. Cholesterol was required for induction of genes involved in acute inflammation, including three genes of the serum amyloid A family, three major histocompatibility class II antigen genes, and various cytokine-related genes. In contrast, cholate induced expression of genes involved in extracellular matrix deposition in hepatic fibrosis, including five collagen family members, collagen-interacting proteins, and connective tissue growth factor. The gene expression findings were confirmed by biochemical measurements showing that cholesterol was required for elevation of circulating serum amyloid A, and cholate was required for accumulation of collagen in the liver. The possibility that these gene expression changes are relevant to atherogenesis in C57BL/6J mice was supported by the observation that the closely related, yet atherosclerosis-resistant, C57BL/6ByJ strain was largely resistant to dietary induction of the inflammatory and fibrotic response genes. These results establish that cholesterol and cholate components of the Ath diet have distinct proatherogenic effects on gene expression and suggest a strategy to study the contribution of acute inflammatory response and fibrogenesis independently through dietary manipulation.

Animal Nutritional Physiological Phenomena↗
PubMed1976

Solubilization as a method for studying self-association: solubility of naphthalene in the bile salt sodium cholate and the complex pattern of its aggregation.

Solubilization of uncharged, slightly soluble solutes is shown to be a useful approach for investigating patterns of self-association. The solubility of naphthalene in aqueous solutions of sodium cholate was determined over the concentration range of 0-0.20 mole/liter at 25 degrees. Bile salts such as sodium cholate have many detergent-like properties and exhibit hydrophobic self-association in aqueous solutions. It has become cutomary to describe this aggregation using the model of micelle formation. The naphthalene solubility data show that the CMC for sodium cholate is not well defined. Comparison with solubilization in a typical micelle-forming system, sodium decanesulfonate, shows clearly that sodium cholate does not resemble a micelle-forming system. Further examination of the solubility data in terms of mutual association of naphthalene with aggregate species shows that the self-association of sodium cholate is not consistent with the formation of (a) only large micelles containing 10 or more monomers, (b) only dimers, (c) dimers and large micelles, and (d) any unique oligomer or multimer. A complex pattern of association, including the formation of dimers and one or more higher oligomers, is indicated.

Chemical Phenomena↗
PubMed1981

The stereospecific D-glucose transport activity of cholate extracts from human erythrocyte membranes.

The glucose transport protein of human erythrocyte membranes was solubilized with cholate to facilitate rapid reconstitution and direct glucose transport measurements. This may simplify the isolation of the native glucose transporter. In most experiments the membranes were prepared from fresh blood within 8 h, frozen in liquid nitrogen and stored at -70 degrees C to minimize proteolytic degradation. Solubilization with 25 mM cholate in the presence of 200 mM NaCl at pH 8.4 for 12 min at room temperature gave a high D-glucose transport activity. The solubilized mixture contained 20% of the total membrane protein, only 6% of the polypeptides of molecular weight around 90000, 23% of the polypeptides of molecular weight around 55000, 30% of the phospholipids and at least 6% of the stereospecific D-glucose transport activity. At cholate concentrations up to 22 mM the ratio of solubilized phospholipids to cholate increased steeply, concomitant with an increase in solubilized activity. Above 30 mM cholate the activity diminished. At 4 degrees C the activity of the extract decreased rapidly within the first day and slowly during the next few days. The initial changes seem to have produced a fairly stable, but not native form or fragment of the transporter. When 20 mM EDTA and 5 mM dithioerythritol were included in the solubilization mixture a high activity was preserved for about one day.

Blood Glucose↗
PubMed1993

Altered expression of unidirectional extrusion routes for methotrexate and cholate in an efflux variant of L1210 cells.

The specificity and function of two unidirectional anion-efflux pumps in mouse L1210 cells were evaluated using a variant cell line selected for growth in the presence of cholate and bromosulfophthalein. Transport analysis revealed that cholate efflux in the variant L1210/C7 cell line had declined 8-fold, due to the loss of a bromosulfophthalein-sensitive efflux system, the major extrusion route for cholate in parental cells. Efflux measurements showed further that a bromosulfophthalein-sensitive efflux system for methotrexate was also absent in L1210/C7 cells. Total unidirectional efflux of methotrexate, however, was similar in the variant and parental cells, since the loss in the bromosulfophthalein-sensitive system was compensated by a rise in a second probenecid-sensitive route. The latter was identified from inhibitor studies to be the same system which acts as a minor efflux route for methotrexate in parental cells. These results support the hypothesis that L1210 cells contain a bromosulfophthalein-sensitive efflux system which mediates the unidirectional extrusion of either methotrexate or cholate, and a second probenecid-sensitive route which differs from the bromosulfophthalein-sensitive system in inhibitor specificity and also in its ability to transport methotrexate but not cholate.

Animals↗
PubMed1985

Effects of phospholipids on the specific binding of [3H]spiroperidol to the cholate extract of rat brain synaptic membranes.

Effects of phospholipids including PC, PE, PI, and PS on the specific [3H]SPD binding to the solubilized dopamine receptors were examined in the cholate extracts of the cortical and striatal synaptic membranes (P2M) of the rat brain. PC and PS, but not PE or PI, at 0.4 mM greatly enhanced the specific [3H]SPD binding to the cholate extracts of both cortical and striatal P2M fractions. PC and PS did not enhance the specific [3H]DA binding to the same cholate extracts. The enhancing effects of PC and PS were temperature-dependent and in a dose-response manner peaking at 0.4 mM and 0.2 mM respectively. Such temperature dependence indicated that the PC effects were not due to trapping of [3H]SPD by PC but represented a possible DAR-PC complex formation that allowed higher binding for the ligand. Failure of natural cerebellar P2M in enhancing the [3H]SPD binding to the cholate extract supports the notion that fluidity of the phospholipids is required for the binding or the formation of the DAR-PC (or PS) complex. Scatchard analysis of the [3H]SPD binding to the cholate extract in the absence or presence of PC or PS indicated that the PC or PS enhancement of the ligand binding may be mainly due to an increase in the number of binding sites since both PC and PS significantly increased the Bmax but not the Kd of the binding.

Animals↗
PubMed1996

Effect of water-soluble polymers on the state of aggregation, vesicle size, and phase transformations in mixtures of phosphatidylcholine and sodium cholate.

The state of aggregation and the steady-state size of mixed aggregates made of phospholipids and surfactants are both determined by the surfactant/lipid ratio in the mixed aggregates (Re). Water-soluble polymers, such as dextrans and polyethylene glycols (PEGs) of different molecular weights, induce reversible aggregation of phospholipid vesicles, mostly due to dehydration of the vesicle surface and depletion forces, and only at much higher concentrations, PEGs (but not dextran) also induce irreversible size growth of the vesicles. Here we show that the water-soluble polymers dextrans and PEGs do not affect the vesicle-micelle phase boundaries in mixtures of phosphatidylcholine and the anionic surfactant sodium cholate. By contrast, these polymers affect markedly the steady-state size of cholate-containing vesicles. As compared with pure phosphatidylcholine vesicles, the cholate-containing vesicles have a lower tendency to undergo polymer-induced aggregation, probably due to the electrostatic repulsion between the negatively charged vesicles, but a higher tendency to undergo irreversible size growth at relatively low polymer concentrations. Such irreversible size growth was observed not only for PEG but also for dextran, which in the absence of cholate is incapable of inducing vesicle size growth. These findings are consistent with the prevailing concept that the polymer-induced size growth is due to the effect of large structural fluctuations in the bilayers of deformed aggregated vesicles, the surface of which is dehydrated by the polymer. The presence of cholate in the bilayers at sufficiently high concentrations induces such fluctuations, yielding irreversible size growth within the clusters of dehydrated vesicles formed upon mixing with polymers.

Cholic Acid↗
PubMed1997

Promotion of oral insulin absorption in diabetic rabbits using pH-dependent coated capsules containing sodium cholate.

The hypoglycemic effect of oral insulin (40 U) capsules coated with a pH-dependent soluble polymer (Eudragit S100) and containing various doses of sodium cholate (20, 50, 100 mg) was studied in alloxan-hyperglycemic rabbits and compared with that of s.c. insulin injection (20 U). Sodium cholate (20 and 50 mg/capsule) produced a dose-related enhancement of an insulin-induced decrease in the blood glucose level. Insulin capsules containing sodium cholate (50 mg/capsule) produced a steady reduction of the blood glucose level reaching 69% of the initial values (P < 0.01) by 3 h and 48% (P < 0.001) by 5 h after administration. This capsule produced an AUC0-5 h of 125 +/- 14.8 mg.h/dl with relative hypoglycemia (R.H.) of 25.8% compared with insulin s.c. The capsules containing sodium cholate (100 mg), however, did not significantly (P > 0.05) improve the hypoglycemic effect of insulin more than the smaller dose (50 mg/capsule) producing an AUC and R.H. of 135 +/- 12.3 mg.h/dl and 27.9%, respectively. The capsule coated with Eudragit S100 and containing insulin mixed with sodium cholate seems to be a promising formulation to overcome the unavailability of oral insulin.

Administration, Oral↗
PubMed1975

The selective inhibition of chenodeoxycholate synthesis by cholate metabolites in man.

1. Seven normal volunteers took 0-28--0-42 mmol (100--150 mg) of deoxycholate by mouth. This resulted in a reduced proportion of chenodeoxycholate in bile and an increased proportion of deoxycholate. Cholate was unchanged. 2. Cholate and chenodeoxycholate pools and rats of synthesis were determined in four of the subjects by simultaneously labelling each pool with 14C-labelled bile acids. The chenodeoxycholate pool and rate of synthesis decreased after deoxycholate administration. Cholate synthesis and pool size did not change appreciably. 3. The proportion of deoxycholate in bile samples of sixty-two subjects with intact enterohepatic circulation was found to be inversely related to the proportion of chenodeoxycholate in bile, but not to the cholate. 4. It is suggested that inhibition of chenodeoxycholate synthesis by deoxycholate, the principal bacterial product of cholate, regulates the size of the chenodeoxycholate pool independently of the total amount of bile salt.

Bile↗
PubMed1983

Effect of sodium cholate on the catalytic and structural properties of phosphorylase b.

Sodium cholate at millimolar concentration is able to induce activity in rabbit muscle phosphorylase b in the absence of AMP. The maximum activation of the enzyme in presence of 7 mM sodium cholate was 24% of that achieved by 1 mM AMP. Other bile salts tested showed a negligible activating effect. The Ka for AMP was lowered fivefold by 5 mM of the steroid detergent, while the cooperative binding of the nucleotide was abolished. Phosphorylase b', a modified form of phosphorylase in which the phosphorylation site has been removed by limited tryptic attack, presented an activation profile similar to that of phosphorylase b. In contrast, phosphorylase a was inhibited by the bile salt, while the activity of liver phosphorylase b was not significantly affected. Modification of the AMP site of the enzyme with 2,3-butanedione could not inhibit sodium-cholate-induced activity. tert-Butanol, an organic solvent activator of phosphorylase b, was found to enhance the activity induced by sodium cholate. The interaction of sodium cholate and phosphorylase b was also followed by difference spectroscopy using a fluorescein isothiocyanate--phosphorylase b conjugate. Furthermore, measurements of electron spin resonance demonstrated that the mobility of a spin-label bound at buried--NH2 groups of phosphorylase b decreases cooperatively with increasing bile salt concentration.

Adenosine Monophosphate↗
PubMed1980

An analysis of the choleretic effects of infusions of sodium cholate in the guinea-pig.

The choleretic effects of infusions of sodium cholate, with and without the simultaneous infusion of taurine was compared with the choleretic effect of infusions of sodium taurocholate at rates ranging from 20--70 nmole/min. g. liver in anaesthetized guinea-pigs. Sodium cholate was secreted in bile mainly conjugated with taurine and with glycine. 10% was secreted unconjugated. Not more than 10% of the total bile salts secreted may have undergone reduction at C-3. The increase in bile flow with sodium cholate was generally greater than that with sodium taurocholate. The additional flow could not be correlated with the presence of glycocholate or free cholate in bile, and may be due to an action of cholate on biliary secretory mechanisms before the bile salt is secreted into the canaliculi.

Animals↗
PubMed1985

Cholate-dependent killing of Giardia lamblia by human milk.

We showed previously that nonimmune human milk (NHM) kills Giardia lamblia trophozoites in vitro and presented evidence that killing requires the bile salt-stimulated lipase of milk. Since this enzyme is activated by bile salts, killing should be dependent on the presence of bile salts. We now show that killing by fresh NHM or NHM stored at -70 degrees C is totally dependent on sodium cholate (a bile salt). With less than 0.4 mM cholate, no parasites were killed, whereas with 1 mM cholate, greater than 99.7% were killed by 5% NHM in 30 min. Moreover, killing activity was completely heat labile. The G. lamblia-killing activity of human milk was greatly altered by storage at -10 or -20 degrees C. In less than 23 days, the 50% lethal dose decreased, cholate dependence was lost, and killing activity became heat stable. In contrast, the activity of milk stored at -70 degrees C remained unchanged. Milk lipase activity, like killing activity, became cholate independent during storage at -10 or -20 degrees C. On the basis of these results, we hypothesize that killing of G. lamblia by fresh NHM or NHM stored at -70 degrees C depends on bile salt-stimulated lipase, which must be activated by bile salts. In contrast, NHM stored at -20 degrees C accumulated free fatty acids which kill G. lamblia. In support of this thesis, milk stored at -10 degrees C had a concentration of 18.7 mM free fatty acids compared with only 1.1 mM in an identical sample stored at -70 degrees C.

Cholic Acid↗
PubMed1984

Sodium cholate interactions with rabbit's pulmonary surfactant.

In order to assay the possibility that sodium cholate interacts with pulmonary surfactant, we obtained bronchoalveolar lavage fluid from lungs of adult rabbits and measured the hysteresis area of surface tension-area loops of the bronchoalveolar lavage fluid in a Wilhelmy surface tension balance, before and after the addition of sodium cholate to reach different concentrations. We observed a biphasic behavior: at a low concentration of sodium cholate (1.5 x 10(5) mol/l; n = 6) the hysteresis area increased (p less than 0.05) as compared to its control (initial) area, meanwhile at a higher concentration (5 x 10(-5) mol/l; n = 6) the hysteresis area decreased (p less than 0.025), revealing a likely interaction of sodium cholate with pulmonary surfactant. We conclude that sodium cholate is able to interact in vitro with lung surfactant.

Animals↗
PubMed1976

Experimental evidence for high-temperature organic fractional superconduction in cholates.

Experimental data are presented indicating that six organic compounds (homologous cholates) possess properties associated with high-temperature superconductivity. From magnetic and electrical measurements it is deduced that behavior resembling superconductivity occurs below characteristic transition temperatures in small domains included in the insulating bulk of the sample material, which is therefore designated a fractional o Type III superconductor. The six cholates exhibit this superconductivity below transition temperatures ranging from approximately 7.5 degrees K for sodium dioxycholate to 277 degrees K for sodium cholanate. It has been further established that the diamagnetic shifts with temperature cannot be attributed to ferrielectric, ferroelectric, or capacitive effects. Below the transition temperatures the cholates behave like perfect diamagnets, susceptible to forceful repulsion by a moderate magnetic field. Observed in a sensitive susceptometer, magnetic flux trapped in the material gave rise to a 3% remnant magnetic moment. Studied in particular detail were sodium cholate, sodium deoxycholate, and lithocholic acid, which showed transition temperatures of 30 degrees K, 60 degrees K, and 130 degrees K respectively. The hydrophobic property of the closed four-ring structure (R-group) common to the cholates, along with the hydrophilic property of the carboxylate group (S-group), are responsible for domain formation. Because of those properties, clustering of the S-groups occurs when traces of water are introduced into the material. When followed by slow desiccation, the clusters form the micelles constituting the superconducting domains.

Cholic Acids↗
PubMed1995

Deoxycholate and cholate modulate the source of cholesterol substrate for bile acid synthesis in the rat.

In the current study, the role of the supply of preformed and newly synthesized cholesterol for the feedback control of the synthesis of different bile acids and the secretion of biliary cholesterol was investigated. To define these cholesterol fluxes and the possibility of a different modulation by bile acids with different suppressive capacities, a continuous labeling with tritiated water was used in rats with an extracorporeal bile duct receiving intraduodenal infusions of taurocholate or taurocholate plus deoxycholate. After bile acid pool depletion (6 to 9 hours) total muricholate, cholate, and chenodeoxycholate synthesis was variably increased (24% to 93%) during an infusion of 304 mumol taurocholate/kg per hour. The increase in bile acid synthesis and biliary cholesterol output was predominantly due to the utilization of preformed (unlabeled) cholesterol. The addition of 52 mumol/kg per hour of deoxycholate to 258 mumol/kg per hour of taurocholate had a comparable effect. In the late period (30 to 54 hours), the taurocholate infusion had little impact on total muricholate and chenodeoxycholate synthesis but caused by a significant increase of the proportion from performed cholesterol. Both total cholate production and its synthesis from de novo (labeled) cholesterol was inhibited by 30% (P < .05) and 64% (P < .01), respectively. The secretion rate of total and de novo biliary cholesterol was higher (65% and 72%; P < .01) compared with controls. In comparison, the combined bile acid infusion led to a further increase of total muricholate synthesis (P < .05), which was again due to an enhanced synthesis from performed cholesterol (P < .001). Similar changes were observed in chenodeoxycholate. The more pronounced suppression of total cholate synthesis by 81% (P < .05) was due to a diminished cholate synthesis from both de novo cholesterol by 72% (P < .001) and preformed cholesterol by 91% (P > .05). We conclude that the modulation of the synthesis of the various primary bile acids in the rat differs and feedback regulation of cholate synthesis by taurocholate and deoxycholate is mediated by different mechanisms of control, including inhibition of cholesterol 7 alpha-hydroxylase, HMG-CoA reductase, and uptake of lipoprotein cholesterol.

Animals↗
PubMed1996

3 alpha, 7 alpha, 12 alpha-trihydroxy-24-nor-5 beta-cholan-23-sulfonate: synthesis and suitability for the study of cholate transport.

In order to facilitate the study of transport processes of unconjugated C-24 bile salts, simple syntheses of 3 alpha, 7 alpha, 12 alpha-trihydroxy-24-nor-5 beta-cholan-23-sulfonate (norcholansulfonate) and 3 alpha, 7 alpha, 12 alpha-trihydroxy-24-nor-5 beta-[7 beta 5H] cholan-23-sulfonate were devised. The hydrophilic-hydrophobic properties of norcholansulfonate, as determined by its chromatographic behavior as well as by its partition between l-octanol and water, are more similar to those of cholyltaurine than to those of cholate. Self-association of norcholansulfonate in phosphate buffer, pH 7.4, with an ionic strength of 150 mM begins at a concentration of about 1 mM, comparable to that of cholyltaurine and cholate, as determined by spectral changes in fluorescence emissions of {N-[7-(4-nitrobenzo-2-oxa-1, 3-diazol)]-7b-amino-3a, 12a-dihydroxy-5b-cholan-24 - oyl}-2'-aminoethanesulfonate (7 beta-NBD-NCT). The apparent CMC value obtained from solubilization of the dye Orange OT, 8.5 mM, is comparable to that of cholytaurine. 7.5 mM, and lower than that of cholate, 9.5 mM. Norcholansulfonate is readily taken up by rat liver and completely excreted unmetabolized into bile with about the same secretion maximum (Tm) as cholyltaurine. Biliary excretion of norcholansulfonate is inhibited by cholyltaurine, and, vice versa, norcholansulfonate inhibits cholyltaurine secretion. Concerning metabolism and excretion, norcholansulfonate with the sulfonate group in the position where cholate has the carboxylate group should behave as an appropriate cholate analogue in mediated transport processes.

Animals↗
PubMed2006

Enantioseparation of palonosetron hydrochloride by micellar electrokinetic chromatography with sodium cholate as chiral selector.

The enantioseparation of four stereoisomers of palonosetron hydrochloride by micellar electrokinetic chromatography using sodium cholate as chiral surfactant was described. Sodium cholate was shown to be effective in separating palonosetron hydrochloride stereoisomers. For method optimization, several parameters such as sodium cholate concentration, buffer pH and concentration, the types and concentration of organic modifiers and applied voltage, on the enantioseparation were evaluated and the optimum conditions were obtained as follows: 30 mM borate buffer (pH 9.40) containing 70 mM sodium cholate and 20% (v/v) methanol with an applied voltage of 20 kV. Under these conditions, baseline separation of palonosetron hydrochloride stereoisomers was achieved within 18 min.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed2003

Characterisation of a Bifidobacterium strain with acquired resistance to cholate--a preliminary study.

The susceptibility levels against bile salts (ox gall) and sodium cholate of 19 Bifidobacterium strains from different origins ranged between 0.125% and 2.0% and 0.05% and 0.4%, respectively. Seven of these strains were subsequently selected for the isolation of sodium cholate resistant derivatives by exposure to gradually increasing concentrations of this compound. Derivatives resistant to at least 1.2% of cholate were obtained from Bifidobacterium bifidum CECT 4549 and B. bifidum M6. Further analysis of the CECT 4549 derivative indicated that the phenotype induced was stable; the enzymatic activities analysed remained unchanged and no major rearrangements of chromosomal DNA were produced. However, the cells of the resistant derivative were smaller and more regular in average size than those of the original strain. In addition, the derivative had lost the ability to use lactose, fructose and galactose, and showed reduced expression levels of two membrane proteins of 78 and 114 kDa. Finally, the resistant strain displayed higher survival and lower growth inhibition in the presence of cholate than the original strain.

Bifidobacterium↗