Tubulovesicular Transport of Horseradish Peroxidase in Isolated Rat Hepatocyte Couplets: Effects of Low Temperature, Cytochalasin B and Bile Acids

Sakisaka, Shotaro; Harada, Masaru; Gondo, Kazuhisa; Yoshitake, Masao; Tanikawa, Kyuichi

doi:10.1002/hep.1840200434

Cited by 14 publications

(7 citation statements)

References 30 publications

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“…The molecular mechanisms by which DHCA exerts its hypercholeretic action remain unknown. In contrast to UDCA and TUDCA, which promote tubule-vesicular transport in hepatocytes [6], [25], [26], earlier studies have indicated that DHCA increases the canalicular bile flow via a microtubule-independent mechanism [15]. Accordingly, it was not surprising that colchicine did not modify the intrinsic and secretin-insensitive hydrocholeretic action of DHCA in our in vivo model.…”

Section: Discussioncontrasting

confidence: 55%

Ursodeoxycholic Acid Is Conjugated with Taurine to Promote Secretin-Stimulated Biliary Hydrocholeresis in the Normal Rat

et al. 2011

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Background & AimsSecretin induces bicarbonate-rich hydrocholeresis in healthy individuals, but not in untreated patients with primary biliary cirrhosis (PBC). Ursodeoxycholic acid (UDCA) – the first choice treatment for PBC – restores the secretin response. Compared with humans, secretin has poor effect in experimental normal-rat models with biliary drainage, although it may elicit hydrocholeresis when the bile-acid pool is maintained. In view of the benefits of UDCA in PBC, we used normal-rat models to unravel the acute contribution of UDCA (and/or taurine-conjugated TUDCA) for eliciting the biliary secretin response.MethodsIntravascular and/or intrabiliary administration of agonists and inhibitors was performed in normal rats with biliary monitoring. Secretin/bile-acid interplay was analyzed in 3D cultured rat cholangiocytes that formed expansive cystic structures with intralumenal hydroionic secretion.Results In vivo, secretin stimulates hydrocholeresis upon UDCA/TUDCA infusion, but does not modify the intrinsic hypercholeretic effect of dehydrocholic acid (DHCA). The former effect is dependent on microtubule polymerization, and involves PKCα, PI3K and MEK pathways, as shown by colchicine (i.p.) and retrograde biliary inhibitors. In vitro, while secretin alone accelerates the spontaneous expansion of 3D-cystic structures, this effect is enhanced in the presence of TUDCA, but not UDCA or DHCA. Experiments with inhibitors and Ca2+-chelator confirmed that the synergistic effect of secretin plus TUDCA involves microtubules, intracellular Ca2+, PKCα, PI3K, PKA and MEK pathways. Gene silencing also demonstrated the involvement of the bicarbonate extruder Ae2.ConclusionsUDCA is conjugated in order to promote secretin-stimulated hydrocholeresis in rats through Ae2, microtubules, intracellular Ca2+, PKCα, PI3K, PKA, and MEK.

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Section: Discussioncontrasting

confidence: 55%

Ursodeoxycholic Acid Is Conjugated with Taurine to Promote Secretin-Stimulated Biliary Hydrocholeresis in the Normal Rat

et al. 2011

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“…In contrast, we could demonstrate mannan inhibitable HRP secretion at 0.8 mg/mL. Thus, when HRP is applied at concentrations ranging between 1 mg/mL and 10 mg/mL as in morphological and perfusion studies [7, 8, 20, 21, 46] the proportion due to receptor-mediated endocytosis cannot be ignored, although at such HRP concentrations uptake by isolated hepatocytes is mainly by a fluid-phase mechanism.…”

Section: Discussionmentioning

confidence: 71%

Receptor-Mediated and Fluid-Phase Transcytosis of Horseradish Peroxidase across Rat Hepatocytes

Ellinger

Fuchs

2010

Journal of Biomedicine and Biotechnology

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Horseradish peroxidase (HRP) is often used as a fluid-phase marker to characterize endocytic and transcytotic processes. Likewise, it has been applied to investigate the mechanisms of biliary secretion of fluid in rat liver hepatocytes. However, HRP contains mannose residues and thus binds to mannose receptors (MRs) on liver cells, including hepatocytes. To study the role of MR-mediated endocytosis of HRP transport in hepatocytes, we determined the influence of the oligosaccharid mannan on HRP biliary secretion in the isolated perfused rat liver. A 1-minute pulse of HRP was applied followed by marker-free perfusion. HRP appeared in bile with biphasic kinetics: a first peak at 7 minutes and a second peak at 15 minutes after labeling. Perfusion with 0.8 mg/mL HRP in the presence of a twofold excess of mannan reduced the first peak by 41% without effect on the second one. Together with recently published data on MR expression in rat hepatocytes this demonstrates two different mechanisms for HRP transcytosis: a rapid, receptor-mediated transport and a slower fluid-phase transport.

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“…Recent studies have found that the transcytotic vesicle transport in hepatocytes is important in the movement of fluid-phase markers, proteins and ligands (18)(19)(20)(21) between the sinusoidal membrane and the bile cana- liculus. However, the role of transcytotic vesicle transport in bile acid transport has not been clarified.…”

Section: Discussionmentioning

confidence: 99%

Papaverine Inhibits Bile Acid Excretion in Isolated Perfused Rat Liver

et al. 1994

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We investigated the effects of papaverine on bile acid excretion into bile in the presence of infusions of taurocholic acid, tauroursodeoxycholic acid, taurochenodeoxycholic acid and taurodehydrocholic acid in a single-pass, isolated perfused rat liver model. Although continuous infusion of papaverine (1.6 mumol/min) did not reduce bile acid excretion in the presence of low-dose (1.0 mumol/min) infusions of taurocholic acid or tauroursodeoxycholic acid, papaverine significantly inhibited biliary excretion of bile acids in the presence of low-dose taurochenodeoxycholic acid (-50%) and high-dose (3.0 mumol/min) taurocholic acid (-54%), tauroursodeoxycholic acid (-37%) and taurodehydrocholic acid (-31%). During continuous infusion of taurocholic acid (3 mumol/min), a 15-min infusion of papaverine (3.2 mumol/min) reduced bile acid excretion significantly; however, total uptake of bile acid was slightly decreased by the papaverine infusion. Bile acid excretion increased over the baseline value after the papaverine infusion was stopped and then returned to baseline. These results suggest that papaverine does not affect the uptake phase of bile acids at the sinusoidal membrane but may affect the intracellular transport phase or the excretory phase at the bile canalicular membrane. When taurocholic acid was infused at a constant rate of 3 mumol/min for 20 min without papaverine and then stopped, bile acid excretion decreased gradually and was nearly zero by 52 min. Cumulative bile acid excretion in the 52 min after the end of the infusion reached 3.3 +/- 0.2 mumol/gm liver and represented the storage capacity of the liver.(ABSTRACT TRUNCATED AT 250 WORDS)

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Tubulovesicular Transport of Horseradish Peroxidase in Isolated Rat Hepatocyte Couplets: Effects of Low Temperature, Cytochalasin B and Bile Acids

Cited by 14 publications

References 30 publications

Ursodeoxycholic Acid Is Conjugated with Taurine to Promote Secretin-Stimulated Biliary Hydrocholeresis in the Normal Rat

Ursodeoxycholic Acid Is Conjugated with Taurine to Promote Secretin-Stimulated Biliary Hydrocholeresis in the Normal Rat

Receptor-Mediated and Fluid-Phase Transcytosis of Horseradish Peroxidase across Rat Hepatocytes

Papaverine Inhibits Bile Acid Excretion in Isolated Perfused Rat Liver

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