scholarly journals Acute effects of cholestatic and choleretic bile salts on vasopressin- and glucagon-induced hepato-biliary calcium fluxes in the perfused rat liver

1992 ◽  
Vol 283 (2) ◽  
pp. 575-581 ◽  
Author(s):  
Y Hamada ◽  
A Karjalainen ◽  
B A Setchell ◽  
J E Millard ◽  
F L Bygrave

The effects were investigated of the choleretic bile salt glycoursodeoxycholate (G-UDCA) and of the cholestatic bile salt taurochenodeoxycholate (T-CDCA) on changes in perfusate Ca2+, glucose and oxygen and in bile calcium and bile flow induced by the administration of (a) vasopressin, (b) glucagon and (c) glucagon plus vasopressin together to the perfused rat liver [Hamada, Karjalainen, Setchell, Millard & Bygrave (1992) Biochem. J. 281, 387-392]. G-UDCA itself increased the secretion of calcium in the bile several-fold, but its principal effect was to augment each of the above-mentioned metabolic events except glucose and oxygen output; particularly noteworthy was its ability to augment the ‘transients’ in bile calcium and bile flow seen immediately after the administration of vasopressin with or without glucagon. T-CDCA, by contrast, produced opposite effects and attenuated all of the parameters measured, and in particular the transients in bile calcium and bile flow. The data provide evidence of a strong correlation between calcium fluxes occurring on both the sinusoidal and the bile-canalicular membranes and that all are modifiable by glucagon, Ca(2+)-mobilizing hormones and bile salts.

1995 ◽  
Vol 108 (4) ◽  
pp. A1205
Author(s):  
T. You ◽  
S. Güldütuna ◽  
S. Bhatti ◽  
U. Leuschner

2001 ◽  
Vol 281 (1) ◽  
pp. G85-G94 ◽  
Author(s):  
Bo Yang ◽  
Ceredwyn E. Hill

Canalicular glutathione secretion provides the major driving force for bile acid-independent bile flow (BAIF), although the pathways involved are not established. The hypothesis that GSH efflux proceeds by a route functionally distinct from the high-affinity, low-capacity, mrp2-mediated pathway was tested by using perfused rat liver and three choleretic compounds that modify biliary secretion of GSH (the dihydropyridine nifedipine and organic anion probenecid) or GSSG [sodium nitroprusside (SNP)]. Whereas nifedipine (30 μM) stimulated GSH secretion and blocked SNP-stimulated GSSG efflux and choleresis, SNP (1 mM) was ineffective against nifedipine-stimulated GSH efflux or BAIF, suggesting that most GSSG exits through a GSH-inhibitable path independent of high-affinity GSSG/glutathione conjugate transport. Three observations support this proposal. SNP, but not nifedipine, significantly inhibited bromosulfophthalein (BSP, 1 μM) excretion. Probenecid (1 mM) blocked resting or nifedipine-stimulated GSH secretion but only weakly inhibited BSP excretion. Glutathione, but not BSP, efflux capacity was reduced following partial hepatectomy. We suggest GSH efflux is mediated by a high-capacity organic anion pathway capable of GSSG transport when its high-affinity route is saturated.


2009 ◽  
Vol 297 (3) ◽  
pp. G520-G531 ◽  
Author(s):  
S. Lukovac ◽  
E. L. Los ◽  
F. Stellaard ◽  
E. H. H. M. Rings ◽  
H. J. Verkade

Essential fatty acid (EFA) deficiency in mice has been associated with increased bile production, which is mainly determined by the enterohepatic circulation (EHC) of bile salts. To establish the mechanism underlying the increased bile production, we characterized in detail the EHC of bile salts in EFA-deficient mice using stable isotope technique, without interrupting the normal EHC. Farnesoid X receptor (FXR) has been proposed as an important regulator of bile salt synthesis and homeostasis. In Fxr −/− mice we additionally investigated to what extent alterations in bile production during EFA deficiency were FXR dependent. Furthermore, we tested in differentiating Caco-2 cells the effects of EFA deficiency on expression of FXR-target genes relevant for feedback regulation of bile salt synthesis. EFA deficiency-enhanced bile flow and biliary bile salt secretion were associated with elevated bile salt pool size and synthesis rate (+146 and +42%, respectively, P < 0.05), despite increased ileal bile salt reabsorption (+228%, P < 0.05). Cyp7a1 mRNA expression was unaffected in EFA-deficient mice. However, ileal mRNA expression of Fgf15 (inhibitor of bile salt synthesis) was significantly reduced, in agreement with absent inhibition of the hepatic bile salt synthesis. Bile flow and biliary secretion were enhanced to the same extent in EFA-deficient wild-type and Fxr −/− mice, indicating contribution of other factors besides FXR in regulation of EHC during EFA deficiency. In vitro experiments show reduced induction of mRNA expression of relevant genes upon chenodeoxycholic acid and a selective FXR agonist GW4064 stimulation in EFA-deficient Caco-2 cells. In conclusion, our data indicate that EFA deficiency is associated with interrupted negative feedback of bile salt synthesis, possibly because of reduced ileal Fgf15 expression.


1992 ◽  
Vol 281 (3) ◽  
pp. 593-595 ◽  
Author(s):  
C Hallbrucker ◽  
F Lang ◽  
W Gerok ◽  
D Häussinger

The effects of aniso-osmotically and amino-acid-induced cell-volume changes on bile flow and biliary taurocholate excretion were studied in isolated perfused rat liver. With taurocholate (100 microM) in the influent perfusate, hypo-osmotic exposure (225 mosmol/l) increased taurocholate excretion into bile and bile flow by 42 and 27% respectively, whereas inhibition by 32 and 47% respectively was observed after hyperosmotic (385 mosmol/l) exposure. The effects of aniso-moticity on taurocholate excretion into bile was observed throughout aniso-osmotic exposure, even after completion of volume-regulatory ion fluxes and were fully reversible upon re-exposure to normo-osmotic media. Hypo-osmotic cell swelling (225 mosmol/l) increased the Vmax. of taurocholate translocation from the sinusoidal compartment into bile about 2-fold. Also, cell swelling induced by glutamine and glycine stimulated both bile flow and biliary taurocholate excretion. There was a close relationship between the aniso-osmotically and amino-acid-induced change of cell volume and taurocholate excretion into bile. The data suggest that liver cell volume plays an important role in regulating bile-acid-dependent bile flow and biliary taurocholate excretion.


Hepatology ◽  
1995 ◽  
Vol 21 (4) ◽  
pp. 1120-1129 ◽  
Author(s):  
Domenico Alvaro ◽  
Antonio Benedetti ◽  
Alessandro Gigliozzi ◽  
Adriano Bini ◽  
Paola Della Guardia ◽  
...  

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