Disparate Na+-requirement of taurocholate and indocyanine green uptake by isolated hepatocytes.

Uptake of both taurocholate and indocyanine green (ICG) by isolated rat hepatocytes was saturable and obeyed Michaelis-Menten kinetics. Only uptake of taurocholate exhibited Na+-dependence, a phenomenon compatible with active membrane transport. These findings suggest that the mechanisms responsible for hepatocellular uptake of bile acids and anionic dyes differ fundamentally.     

Disparate Na+-requirement of taurocholate and indocyanine green uptake by isolated hepatocytes

Summary Uptake of both taurocholate and indocyanine green (ICG) by isolated rat hepatocytes was saturable and obeyed Michaelis-Menten kinetics. Only uptake of taurocholate exhibited Na⁺-dependence, a phenomenon compatible with active membrane transport. These findings suggest that the mechanisms responsible for hepatocellular uptake of bile acids and anionic dyes differ fundamentally.This work was supported by the Swiss National Science Foundation.The authors thank Mr Th. Weber for technical assistance.     

Influence of dithiocarb on the biliary excretion of paracetamol and bilirubin in rats.

In bile-fistula rats, the biliary elimination of conjugated paracetamol and conjugated bilirubin is diminished by simultaneous administration of dithiocarb. This dithiocarb effect could be the result of the interference with the glucuronidation of the compounds.     

Kinetics and Na-dependence of riboflavin absorption by intestine in vivo

Conclusion The transport of riboflavin across the intestinal mucosa is certainly not by a system of passive diffusion. It necessitates the presence of a specific transporter in the membrane, thus explaining saturation kinetics noted. The transport is dependent on the presence of Na⁺ in the perfusion medium. However, it is not as yet possible to say whether transport is against an electrochemical gradient or a system of facilitated diffusion with simple equilibrium of concentrations extra-and intra-cellular.

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Résumé L'absorption intestinale de la riboflavine est mesurée in vivo par perfusion d'un segment proximal du jéjunum chez le rat. Le transport de la vitamine à travers la muqueuse intestinale suit une cinétique de saturation (K _t =3M; V _max =0,26 nMole par min et par g de tissu frais). Il est fortement réduit (de 40 à 50%) lorsqu'on substitue au NaCl isotonique du milieu de perfusion du mannitol ou du LiCl isotoniques.

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Acknowledgements. We should like to thank Prof.B. Blanc who made possible the completion of this work, Prof.W. Wilbrandt and Prof.G. Semenza for their advice and criticism. The work was supported by the Foundation pour la Recherche Nutritionelle (financed by Zyma S. Y., Nyon and Union Laitière Vaudoise, Lausanne).     

Influence of dithiocarb on the biliary excretion of paracetamol and bilirubin in rats

Summary In bile-fistula rats, the biliary elimination of conjugated paracetamol and conjugated bilirubin is diminished by simultaneous administration of dithiocarb. This dithiocarb effect could be the result of the interference with the glucuronidation of the compounds.     

Physicochemical studies of indocyanine green (ICG): absorbance/concentration relationship,pH tolerance and assay precision in various solvents

Summary Indocyanine green (ICG) obeyed the Beer-Lambert law within the concentration range 1.25 g/ml–10.0g/ml in distilled water, methanol, dimethylformamide (DMF), 1.2-propanediol and aqueous buffers (pH 9.0), but only up to 7.5 g/ml in human bile and 0.5% human albumin, and only to 5.0 g/ml in human duodenal fluid. ICG was rapidly (<1 h) decomposed to a colorless derivative at pH<5 and >11, but remained relatively stable for 48 h at pH 8–10. ICG is an indicator and a weak acid with a pKa of 3.27. In bile stabilized with 25% methanol, the precision of the method (CV) is 5% and the accuracy is 106–127%.     

Adhesion of human red blood cells to polystyrene. Influence of sodium chloride concentration and of neuraminidase treatment.

The adhesion on polystyrene of glutaraldehyde-fixed human red blood cells was found to increase with NaCl concentration. Half of the maximum of irreversible adhesion was obtained in 2.2 mM NaCl for neuraminidase-treated cells and in 5.5 mM NaCl for the untreated cells.     

Oxidation of bilirubin with chloranil. A simple method for preparing isomerically pure biliverdin

Summary Isomerically pure biliverdin IXa can be prepared in high yield through dehydrogenation of bilirubin IXa with chloranil-picric acid in chloroform containing t-butanol.     

Influence of pregnancy and fibrosarcoma on hepatic mitochondrial proteins of mice

Summary Non-pregnant, pregnant and fibrosarcoma-bearing non-pregnant mice differ in their total hepatic mitochondrial protein content, as well as the electrophoretic pattern following separation on SDS acrylamide gels.     

Oxygenation of a dipyrromethene model for bilirubin: formation of a singlet oxygen-like product.

An oxodipyrromethene model compound for bilirubin is found to undergo oxidation to a blue tetrapyrrole and a water-propentdyopent on a silica gel thin layer chromatography plate. The reaction involves ground state oxygen and requires silica gel, although the propentdyopent is an expected product from reaction with singlet oxygen.     

Adhesion of human red blood cells to polystyrene. Influence of sodium chloride concentration and of neuraminidase treatment

Summary The adhesion on polystyrene of glutaraldehyde-fixed human red blood cells was found to increase with NaCl concentration. Half of the maximum of irreversible adhesion was obtained in 2.2 mM NaCl for neuraminidase-treated cells and in 5.5 mM NaCl for the untreated cells.     

Plasma catecholamines in conscious rats: Influence of sodium,stress and heredity

Summary Plasma catecholamines are increased in sodium-loaded rats under both resting and stress conditions. Under stress, Na⁺ resistant rats have lower plasma catecholamines than salt-sensitive ones.Supported in part by grants from Institut National de la Santé et de la Recherche Médicale (INSERM), Centre National de la Recherche Scientifique (CNRS) and Délégation Générale à la Recherche Scientifique et Technique (DGRST).     

Influence of phenobarbital and TCDD on the hepatic metabolism of TCDD in the dog

The influence of phenobarbital and TCDD pretreatment on the formation and biliary excretion of TCDD-metabolites following single doses of 3H-TCDD was investigated. Without pretreatment, 24.5% of the absorbed 3H-TCDD dose was excreted in the bile within 110 h. Phenobarbital did not influence this rate, whereas a single dose of 10 micrograms of unlabeled TCDD/kg b.wt nine days earlier resulted in a doubling of the amount of radioactive material eliminated in the bile (47.4%).