Effect of food and light schedule on bile flow in the rat

Summary In the rat after food intake, whether during the dark or light period, bile flow increases. Food intake seems to be a major factor in the circadian rhythm of bile secretion.     

Ascorbic acid and cholesterol: Effect of graded oral intakes on cholesterol conversion to bile acids in guinea-pigs

Summary A significant correlation between liver ascorbic acid (AA) and total bile acids or liver bile acids has been established in guinea-pigs by direct determination of the bile acids, confirming an earlier hypothesis. The oxidation of cholesterol to bile acids is dependent on the AA status, but it cannot be further stimulated by AA when the animals are already on an adequate intake of the vitamin. This suggests that AA has a hypocholesterolaemic effect over a limited range of AA status.     

Prostaglandin-induced choleresis in the rat.

It could be demonstrated that intraportal infusion of prostaglandin A1 (1 mug/min/100 g body wt.) in Wistar rats significantly increases bile flow. An analysis of the relationship between bile salt excretion and bile flow revealed that this choleresis is due to an increase in the bile salt independent fraction of bile.     

Gallen und Gallensäuren Papierchromatographische Untersuchungen

Summary In cases of bile-scretion disturbances substitution-therapy can be performed using suitable animal biles equivalent to human bile. Comparative investigations have been made to establish which animal bile is in practice the most suitable for bile substitutiontherapy based on its bile acid components.A new paper partition chromatographic method has been applied for separation and identification of free bile acids. Ascending development was used on Schleicher & Schüll 2043b Mgl paper impregnated with 20 v/v% propylene glycol in chloroform. The xylene-methylethylketone 1:1 solvent system gave good separation. The bile acids can be detected by immersing the chromatograms in 20 w/v% SbCl₃ in chloroform followed by drying and heating for 5–10 min at 100–110°C. The spots show intense reddish-violet or blue fluorescence in filtered UV-light (see Table 1).These investigations have shown that human and ox biles are, in contrast to pig bile, physiologically related biological substances regarding their bile acid components.     

Bile Acids: Chemistry, Pathochemistry, Biology, Pathobiology, and Therapeutics

Bile acids and bile alcohols in the form of their conjugates are amphipathic end products of cholesterol metabolism with multiple physiological functions. The great variety of bile acids and bile alcohols that are present in vertebrates are tabulated. Bile salts have an enterohepatic circulation resulting from efficient vectorial transport of bile salts through the hepatocyte and the ileal enterocyte; such transport leads to the accumulation of a pool of bile salts that cycles between the liver and intestine. Bile salt anions promote lipid absorption, enhance tryptic cleavage of dietary proteins, and have antimicrobial effects. Bile salts are signaling molecules, activating nuclear receptors in the hepatocyte and ileal enterocyte, as well as an increasing number of G-protein coupled receptors. Bile acids are used therapeutically to correct deficiency states, to decrease the cholesterol saturation of bile, or to decrease the cytotoxicity of retained bile acids in cholestatic liver disease.     

Role of bile in intestinal absorption of 203Pb in rats.

The author studied absorption of 203Pb after administering intraduodenally 203Pb eliminated with bile. The results obtained were compared with absorption of 203Pb administered into the duodenum as 203PbCl2 in rats forming 2 groups, one with bile ducts cannulated, the other intact. It was found that bile played an important role in absorption of Pb from the gastrointestinal tract. Absorption of Pb203 is significantly reduced if the bile is drained off by means of a canula.     

Lipid sensing and lipid sensors

The field of bile acids has witnessed an impulse in the last two decades. This has been the result of cloning the genes encoding enzymes of bile acid synthesis and their transporters. There is no doubt that the identification of Farnesoid X Receptor (FXR, NR1H4) as the bile acid receptor has contributed substantially to attract the interest of scientists in this area. When FXR was cloned by Forman et al. [1], farnesol metabolites were initially considered the physiological ligands. After identifying FXR and other nuclear receptors as bile acid sensors [2-4], it has become clear that bile acids are involved in the regulation of lipid and glucose metabolism and that these molecules are eclectic regulators of diverse cellular functions. In this review, we will summarize the current knowledge of the functions regulated by bile acids and how their physiological receptors mediate the signaling underlying numerous cellular responses.     

The effect of dietary lactose on the ileal absorption of sodium taurocholate in rats]

When Rats were fed a lactose containing diet, both the absorption rate of sodium taurocholate at the level of ileum and the contents of bile acids of the small intestine were increased. On the contrary, feeding of lactose did not modify the daily fecal excretion of bile acids. It therefore appears that dietary lactose increases the intestinal pool of bile acids by increasing their ileal absorption rate and that this effect of lactose is not subordinated to a modification of bile acid synthesis.     

Serum and bile modifications in the guinea-pig following chronic treatment with PGE1 and PGE2.

PGE1 increases cholesterolemia without lipemia modifications. In bile there are not modifications in cholesterol levels and total lipids appear diminished. PGE2 raise the lipemia and have no effect in cholesterolemia, moreover bile cholesterol and total lipids exhibit no changes. Both PGE1 and PGE2 decreased the bile volume.     

Effect of S-adenosyl-L-methionine on ethynylestradiol-induced impairment of bile flow in female rats

Summary Prevention by S-adenosyl-L-methionine (SAMe) of the bile flow reduction induced by ethynylestradiol (EE) is demonstrated by comparing the flow rate and the bile salt concentration of bile in EE-treated animals with that in animals given both EE and SAMe.SAMe was supplied by Bio Research Co., 20060 Liscate (Milano), Italy.     

Choleretic and cholestatic effects of infused bile salts in the rat.

In rats, at low infusion rates taurocholate (TC), taurochenodeoxycholate (TCDC) and taurodeoxycholate (TCD) each produced an increase in bile flow of 20-50%. However, at high infusion rates (5-20 mumoles min-1kg-1) the cholestatic effects of the bile salts were revealed and the relative toxicity of the bile salts was seen to be TDC greater than TCDC greater than TC.     

Role of bile in intestinal absorption of203Pb in rats

Summary The author studied absorption of²⁰³Pb after administering intraduodenally²⁰³Pb eliminated with bile. The results obtained were compared with absorption of203Pb administered into the duodenum as²⁰³PbCl₂ in rats forming 2 groups, one with bile ducts cannulated, the other intact. It was found that bile played an important role in absorption of Pb from the gastrointestinal tract. Absorption of Pb²⁰³ is significantly reduced if the bile is drained off by means of a canula.     

The amino acid composition of rat bile

Summary The pattern of amino acids in the bile of rats differs from the pattern in the serum of these animals, since bile contains significantly greater amounts of acidic and sulphur-containing amino acids and glycine than serum, while the serum contained more basic amino acids than bile, indicating that secretion of amino acids into bile may involve specific transport processes.Acknowledgments. We thank Mr M. Earlam of Pharmaceuticals Division, Imperial Chemical Industries Limited for the aminoacid analyses, and Dr J. S. Morley for helpful discussion. URF gratefully acknowledges a grant (FO 73/2) from the Deutsche Forschungsgemeinschaft, Bonn-Bad Godesberg, Fed. Rep. of Germany. KGW is recipient of a grant from the Scottish Hospital Research Endowments Trust.     

Formation of omega-muricholic acid and fecal excretion of biliary acids in rats]

Two groups of Rats which were fed the same diet, excreted fecal bile acids of different patterns: in one group, the feces contained a large amount of omega-muricholic acid and very little hydrodeoxycholic acid; in the other group the reversed composition was observed. The first group excreted more total bile acids than the second. This observation suggests that the formation of a large amount of omega-muricholic acid results in an increase in total bile acid fecal excretion.     

Influence of common bile duct cannula size on maximal secretory rate of taurocholate in the rat

Summary The common bile duct of male Sprague-Dawley rats was cannulated with either PE 10 or PE 50 tubing. Maximal secretory rate of taurocholate averaged 389±67 (SD) and 657±115 nmoles·min^–1·g liver^–1 in the PE 10 and PE 50 group, respectively (p<0.005). Maximal bile secretory pressure was significantly higher in the PE 10 group (240±28 vs 174±8 mm H20; p<0.005). When the maximal secretory rate was exceeded, bile flow decreased in both groups but this was accompanied with a decrease in maximal bile secretory pressure in the PE 10 group only. Maximal secretory rate of bile salts is markedly influenced by experimental technique. Use of small caliber common bile duct cannulae leads to partial obstruction and decreases the apparent maximal secretory rate for taurocholate.Acknowledgments. J. Reichen was the recipient of a Faculty Development Award in Clinical Pharmacology from The Pharmaceutical Manufacturer's Association Foundation, and is the recipient of a Research Career Development Award (KO4 AM 1189) from the National Institutes of Health. Supported by National Institutes of Health grant RO1 AM 27597.     

Expansion of the bile acid pool changes the biliary transport characteristics of centrizonal hepatocytes

We investigated whether acinar differences in taurocholate transport are responsible for the increased maximal secretory rate observed after expansion of the bile acid pool. The bile acid pool was expanded by cholate feeding for four days. Periportal and centrizonal hepatocytes were then probed by ante- and retrograde liver perfusion, respectively. In control animals, secretory rate constant (alpha 1) averaged 0.439 +/- 0.123 and 0.104 +/- 0.035 min-1 during ante- and retrograde perfusion, respectively, in the absence of exogenous taurocholate. These values did not significantly change when taurocholate was infused. In cholate-fed animals, alpha 1 was comparable during antegrade perfusion but was significantly reduced (0.038 +/- 0.035, p less than 0.05) during retrograde perfusion in the absence of exogenous taurocholate, presumably owing to induction of cytosolic bile acid binding proteins. During loading with exogenous taurocholate, by contrast, alpha 1 was significantly accelerated (0.252 +/- 0.026; p less than 0.01) in centrizonal hepatocytes from bile-acid fed rats. Expansion of the bile acid pool is able to change the bile salt secretory characteristics of centrizonal hepatocytes toward those of periportal ones.     

Wirkungen von Gallensäure und Vitamin D auf die Kalziumresorption bei der Ratte

Summary Comparison of the effects of vitamin D and the bile salt Taurochenodeoxycholate on calcium absorption in young rats suggests that bile salt enhancement of calcium absorption occurs mainly in the ileum in normal animals but occurs in both duodenum and ileum in rachitic rats. Also suggested is that bile salts mainly assist the entry of calcium into mucosal cells from the gut lumen while vitamin D chiefly aids the egress of calcium from the cells into the extracellular fluid.     

Vitamin C and gallstone formation: A preliminary report

Summary Gallstone formation in hypovitaminotic C guinea-pigs fed a high cholesterol diet was associated with qualitative changes in the gallbladder bile, namely, a high cholesterol concentration, a lowered bile acid content and diminished phospholipid-to-cholesterol and bile acid-to-cholesterol ratio.Acknowledgment. I am indebted to Prof. H. M. Sinclair (Oxford) and Drs K. M. L. Morris (City of London Polytechnic) and G. M. Murphy (Guys Hospital Medical School) for valuable discussion and advice, and to Mr J. A. Rawlings for technical assistance.     

Solubilization of unconjugated bilirubin by bile salts

Summary Freshly precipitated uncojugated bilirubin (UCB) is solubilized rapidly and to a large extent by the sodium salts of di- and trihydroxy bile acids. The solubilization effect depending on bile salt concentration, pH and ionic strength is based on micellar mechanisms.     

Solubilization of unconjugated bilirubin by bile salts.

Freshly precipitated unconjugated bilirubin (UCB) is solubilized rapidly and to a large extent by the sodium salts of di- and trihydroxy bile acids. The solubilization effect depending on bile salt concentration, pH and ionic strength is based on micellar mechanisms.