Intravital Dynamic and Correlative Imaging of Mouse Livers Reveals Diffusion‐Dominated Canalicular and Flow‐Augmented Ductular Bile Flux (original) (raw)
Related papers
2020
1 Center for Information Services and High Performance Computing, Technische Universität Dresden, 01062 Dresden, Saxony, Germany 2) Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Saxony, Germany 3) UCSF, Cardiovascular Research Institute, Department of Biochemistry and Biophysics, California, USA 4) Chair of Scientific Computing for Systems Biology, Faculty of Computer Science, Technische Universität Dresden, 01187 Dresden, Saxony, Germany 5) Center for Systems Biology Dresden, 01307 Dresden, Saxony, Germany 6) Cluster of Excellence Physics of Life, Technische Universität Dresden, 01187 Dresden, Saxony, Germany
Channel-mediated water movement across enclosed or perfused mouse intrahepatic bile duct units
AJP: Cell Physiology, 2002
We previously reported the development of reproducible techniques for isolating and perfusing intact intrahepatic bile duct units (IBDUs) from rats. Given the advantages of transgenic and knockout mice for exploring ductal bile formation, we report here the adaptation of those techniques to mice and their initial application to the study of water transport across mouse intrahepatic biliary epithelia. IBDUs were isolated from livers of normal mice by microdissection combined with enzymatic digestion. After culture, isolated IBDUs sealed to form intact, polarized compartments, and a microperfusion system employing those isolated IBDUs developed. A quantitative image analysis technique was used to observe a rapid increase of luminal area when sealed IBDUs were exposed to a series of inward osmotic gradients reflecting net water secretion; the choleretic agonists secretin and forskolin also induced water secretion into IBDUs. The increase of IBDU luminal area induced by inward osmotic g...
Hepatic Bile Formation: Canalicular Osmolarity and Paracellular and Transcellular Water Flow
Journal of Pharmacology and Experimental Therapeutics, 2019
The purpose of this minireview is to indicate that a new paradigm is developing regarding hepatic bile flow. The focus thus far has been on the carrier-mediated transport of bile acids and other solutes, such as glutathione, which create an osmotic gradient for the transcellular and paracellular flow of water into canaliculi. In addition to the physico-chemical properties of the bile acids, which govern the osmotic gradient, data now exist that the tight junctions, governing paracellular water flow, and Aquaporin-8 water channels, governing transcellular water flow, are regulated independently. Thus, the rate of water flow into the canaliculus in response to bile acid transport is variable and determines canalicular bile acid concentration, which affects the production and solubilization of cholesterol-lecithin vesicles. These new considerations modify thinking regarding the occurrence of cholestasis and its progression and reorient the design of experimental studies that can distinguish the different determinants of bile flow.
Hepatic bile formation: bile acid transport and water flow into the canalicular conduit
American Journal of Physiology-Gastrointestinal and Liver Physiology, 2020
Advances in molecular biology identifying the many carrier-mediated organic anion transporters and advances in microscopy that have provided a more detailed anatomy of the canalicular conduit make updating the concept of osmotically determined canalicular flow possible. For the most part water flow is not transmembrane but via specific pore proteins in both the hepatocyte and the tight junction. These pores independently regulate the rate at which water flows in response to an osmotic gradient and therefore are determinants of canalicular bile acid concentration. Review of the literature indicates that the initial effect on hepatic bile flow of cholestatic agents such as Thorazine and estradiol 17β-glucuronide are on water flow and not bile salt export pump-mediated bile acid transport and thus provides new approaches to the pathogenesis of drug-induced liver injury. Attaining a micellar concentration of bile acids in the canaliculus is essential to the formation of cholesterol-leci...
Intrahepatic bile ducts transport water in response to absorbed glucose
AJP: Cell Physiology, 2002
The physiological relevance of the absorption of glucose from bile by cholangiocytes remains unclear. The aim of this study was to test the hypothesis that absorbed glucose drives aquaporin (AQP)-mediated water transport by biliary epithelia and is thus involved in ductal bile formation. Glucose absorption and water transport by biliary epithelia were studied in vitro by microperfusing intrahepatic bile duct units (IBDUs) isolated from rat liver. In a separate set of in vivo experiments, bile flow and absorption of biliary glucose were measured after intraportal infusion of d-glucose or phlorizin. IBDUs absorbedd-glucose in a dose- and phlorizin-dependent manner with an absorption maximum of 92.8 ± 6.2 pmol · min−1 · mm−1. Absorption of d-glucose by microperfused IBDUs resulted in an increase of water absorption ( J v = 3−10 nl · min−1 · mm−1, P f = 40 × 10−3 cm/sec). Glucose-driven water absorption by IBDUs was inhibited by HgCl2, suggesting that water passively follows absorbed d-...
Bile acid transport across the hepatocyte canalicular meni.brane
2000
Bile acids, which are present at physiological pH val- ues as bile salts, are synthesized in the hepatocyte from cholesterol and secreted across the canalicular (apical) membrane into bile. Bile salts are taken up from blood across the sinusoidal (basal) membrane, in part metabolized within the hepatocyte, and se- creted into bile. The uphill bile salt transport across the canalicular
Functional characterization of hepatic transporters using intravital microscopy
European Journal of Pharmaceutical Sciences, 2013
A better understanding of the role of hepatic transporters in drug elimination is of crucial importance for drug development and therapy. This study examined the usefulness of intravital microscopy to quantitatively evaluate the function of hepatic transporters in the exposed liver of anesthetized rats. In one experiment the function of the organic anion transporting polypeptide (Oatp) in sinusoidal uptake was investigated by administering an Oatp inhibitor, rifampicin, prior to the probe substrate Na-fluorescein. In another experiment, rhodamine 123 was used to quantify the biliary canalicular transporter P-glycoprotein (P-gp, Abcb1a/b) with cyclosporin A as an inhibitor of P-gp activity. Calibrated fluorescence intensity time curves measured in sinusoids and hepatocytes together with cumulative biliary excretion data from control and inhibitor treated animals were analyzed with a three-compartment model. A robust parameter estimation was achieved using nonlinear mixed effects modeling. Rifampicin reduced the hepatic uptake clearance of Na-fluorescein to 25% of the control (p < 0.05) without affecting other parameters. In the presence of cyclosporin A, biliary excretion of rhodamine 123 decreased to 7% of the control (p < 0.01). The novelty of this approach is that it allows a quantitative evaluation of transporter function in the in vivo rat liver.