The effect of amiloride on biliary HCO-3 secretion in the anaesthetized pig

The effect of amiloride on biliary HCO^-₃-secretion in the anaesthetized pig. Acta Physiol Scand 130 , 447–455. Received 20 October 1986, accepted 23 February 1987. ISSN 0001–6772. Institute for Experimental Medical Research, University of Oslo and Surgical Department, Ullevaal Hospital, Oslo, Norway. The present study was performed on 29 anaesthetized pigs and shows that the bile acid ursodeoxycholic acid (UDCA) produces a flow of bile rich in HCO^-₃ compared with taurocholic acid (TCA). The slope relating biliary HCO^-₃ secretion to bile acid secretion was 0.59 (0.44–0.82) and 0.33 (0.29–0.38) during venous infusion of UDCA and TCA, respectively. We next wanted to evaluate the importance of Na⁺/H⁺ ion exchange for biliary HCO^-₃ secretion. High doses of amiloride were employed in order to impair the hepatic Na⁺/H⁺ ion exchanger. It was reasoned that any reduction in H⁺ efflux through the hepatic Na⁺/H⁺ ion exchanger involved in causing biliary HCO^-₃ secretion would be translated into an equimolar fall in biliary HCO^-₃ secretion. We found that amiloride (2.0 ± 10^--⁴ mol l^-1 plasma) reduced UDCA-dependent canalicular HCO^-₃ secretion by 26 (14–35)% without concurrently reducing bile acid secretion. Amiloride (2.9 ± 10^--⁴ mol 1^--¹ plasma) did not significantly reduce secretin-dependent ductular HCO^-₃ secretion. In this group of animals amiloride reduced bile acid secretion by 13 (5–22)%. It is concluded that Na⁺/H⁺ ion exchanger is essential for UDCA-dependent canalicular HCO^-₃ secretion, but not for secretin-dependent ductular HCO^-₃ secretion.     

Quantification of the intrahepatic biliary tree during human fetal development

Development and differentiation of bile ducts have been studied for the understanding of pathogenesis of biliary atresia and other diseases of the intrahepatic biliary tree. The aim of this study is to correlate the type of biliary structure with the size of the portal tract and the gestational age. Twenty-four human livers were studied. Fetuses were assigned to four gestational age groups: group I, up to 20 postfecundation weeks (PFW); group II, from 21–26 PFW; group III, from 27–32 PFW; and group IV, from 33–38 PFW. In each specimen, 30 portal tracts were classified as small, medium, or large according to the diameter of the portal vein. In order to identify the bile duct cells, the sections were immunolabeled with anti-cytokeratin antibody, and the biliary structure was classified as absent (bile ducts (BD) = 0), presence of bile duct cells without lumen (BD = 1), or presence of bile duct with lumen (BD = 2). In the small portal tracts, either there were no biliary structures or just a few. There was a substantial increase in the number of medium portal tracts that included a bile duct as a function of gestational age. The majority of large portal tracts exhibited a bile duct. In human fetus up to 20 PFW, it is possible to find 70% of portal tracts without bile ducts, and at 38 PFW it is expected that more than 50% of the portal tract has a BD > 0. We suggest the use of the diameter of the portal vein and the gestational age for the quantification of biliary structures and the evaluation of maturity of intrahepatic biliary tree. Anat. Rec. 251:297–302, 1998. © 1998 Wiley-Liss, Inc.     

Effect of arterial pH and PCO2 on biliary HCO-3 secretion in the pig

The purpose of the present study was to examine the effect of changes in arterial pH and P^CO2 on biliary HCO_-³ secretion. This was done in order to further characterize the various ion transport mechanisms considered responsible for biliary HC₃ secretion in the pig. Experiments were performed on two groups of six pigs. In both groups arterial pH was varied in steps from pH 7.40 to 7.40, both at P^CO2 5.5 P^CO2 and P^CO2, 10 kPa. In group I (n= 6), data were obtained on the effect of arterial pH and P^CO2 on ductular P^CO2 secretion in bile acid depleted (cholestyramine pretreated), secretin-infused pigs. In group II (n= 6), the effect of pH and P^CO2 on canalicular HCO_-³ secretion was studied in ursodeoxycholic acid (UDCA)-infused pigs (3 μml min^-1 kg^-1 body wt). In group I, biliary HCO_-³ secretion exhibited P^CO2- dependent, positive straight line relationships to arterial pH. An increment in biliary HCO_-³ secretion of 17 (11–24)% was seen during high P^CO2 at pH 7.40. In group II, biliary HCO_-³ secretion exhibited P^CO2-dependent, positive curvilinear relationships to arterial pH. A median increment in HCO_-³ secretion of 37 (20–62)% was seen during elevated P^CO2 at arterial pH 7.40. The linear dependence of ductular HCO_-³ secretion on arterial pH and the effect of elevated HCO_-³ on P^CO2 secretion fit well with findings in other epithelia, where proton transport is thought be driven by a proton pump. A computer simulation provided evidence suggesting that secretin-dependent HCO_-³ secretion does not involve the action of a Na⁺/H⁺ ion exchanger—in contrast to UDCA-dependent HCO_-³ secretion. It is concluded that ductular and canalicular HCO_-³ secretion could be mediated by a proton pump and a Na⁺/H⁺ ion exchanger in addition to canalicular HCO_-³ secretion due to solvent drag and diffusion, respectively.     

促胰液素通过大鼠Cajal间质细胞促进胃平滑肌舒张

观察Cajal间质细胞(interstitial cells of Cajal，ICC)在胃平滑肌收缩的起搏作用，以及促胰液素对ICC促进胃平滑肌细胞舒张的影响。采用大鼠胃体上1/3起搏区及胃窦环行肌肌条以Kreb’s液恒温灌流，通过张力换能器输人生理记录仪记录胃肌条的机械运动。用美蓝加光照选择性损伤ICC，观察促胰液素对胃平滑肌舒张的作用。结果显示：(1)带有ICC的胃体起搏区和胃窦肌条记录到稳定的收缩活动，胃窦收缩频率和振幅较胃体起搏区高。(2)损伤胃环肌层ICC后，导致胃体起搏区和胃窦平滑肌收缩频率与振幅明显下降，运动几乎消失。(3)促胰液素0．06～0．5mg/L明显减少胃体起搏区和胃窦区的收缩频率和振幅，呈剂量依赖性减少。损伤ICC后几乎完全取消促胰液素促进胃肌的舒张作用。抗促胰液素血清和阿托品可阻断促胰液素的作用。     

Colchicine inhibits the effects of secretin on pancreatic duct cell tubulovesicles and HC03 secretion in the pig

Secretin stimulation clears the cytoplasm of intralobular pancreatic duct cells in pigs of tubulovesicles and causes these cells to secrete HCO₃^- into the pancreatic juice. To determine whether the clearance of cytoplasmic tubulovesicles involves the microtubule system and is important for initiation of HCO₃^- secretion, the effect of the microtubule poison colchicine on duct cell morphology and pancreatic HCO₃^- secretion was measured in anaesthetized pigs. Before colchicine, secretin reduced the density of tubulovesicles in the cytoplasm of pancreatic duct cells from 92 ± 8 U to 8 ± 2 U and initiated pancreatic secretion of 176 ± 21 μmol min^-1 HCO₃^-. After colchicine, secretin failed to lower duct cell tubulovesicle density and caused the secretion of only 77 ± 14μmol min^-1 HCO₃^-. By contrast, lumicolchicine, an isomer of colchicine that does not affect microtubules, did not inhibit pancreatic HCO3 secretion. Colchicine did not reduce carbonic anhydrase or Na,K-ATPase activities in in-vitro assays. The clearance of tubulovesicles from the cytoplasm of pancreatic duct cells therefore seems to be microtubule-dependent and important for the pancreatic HCO₃^- secretion.     

Effect of disturbance of the innervation of the liver and loss of bile on biliary and hepatic enzyme activity

Continuous loss of bile from rats with a bile reservoir connected to the common bile duct led to an increase in specific activity of malate, lactate, glutamate, and glucose-6-phosphate dehydrogenases, alkaline and acid phosphatases, urokinase, and histidase in liver homogenates by the seventh day. By the tenth day their specific activity had fallen. After disturbance of the innervation of the rats' livers the ATP concentration fell sharply and the specific activity of the above-mentioned enzymes in the liver was considerably inhibited. During continuous loss of bile, fluctuating changes took place in the specific activity of these enzymes and also of sorbitol dehydrogenase in the bile, starting from the first and continuing until the tenth day of the experiment. Support for the view that these fluctuations were under the control of the nervous system was given by the considerable changes in their character following disturbance of the hepatic innervation.Department of Biochemistry, Moscow Medical Stomatological Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR S. E. Severin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 6, pp. 684–686, June, 1976.     

The developing human biliary system at the porta hepatis level between 29 days and 8 weeks of gestation: A way to understanding biliary atresia. Part 1

The developing biliary system in normal human embryos from 29 days to 8 weeks post-fertilization was studied. The primitive extrahepatic bile duct that originates from the embryonic hepatic foregut diverticulum is in contact with the hepatic anlage from the start of organogenesis and remains so throughout the gestational ages examined. The primitive extrahepatic bile duct maintains continuity with the ductal plate from which intrahepatic bile ducts are eventually formed. Contrary to long-held concepts of biliary development, no 'solid stage' of entodermal occlusion of the common bile duct lumen was found at any stage of gestation in the material investigated. Therefore, biliary atresia is not caused by incomplete vacuolization of the 'solid stage'.     

Immunoglobulin deposits in the biliary remnants of extrahepatic biliary atresia: a study by immunoperoxidase staining in 128 infants

Bile duct remnants taken from 128 infants during surgery for extrahepatic biliary atresia were paraffin embedded prior to immunoperoxidase staining. Immunoglobulin deposits were found in 44 remnants. They were made up of IgM alone in 25 cases and of IgM and IgG in 19. Deposits were observed along the basement membranes of glandular structures. These findings suggest that extrahepatic bilary atresia might be an acquired and evolving disease.     

Arterial supply and biliary drainage of the dorsal liver: A dissection study using controlled specimens

Liver surgeons favor using the entity called the 'dorsal liver' (i.e. the caudate lobe and other paracavally located liver parenchyme of segments 7 and 8). According to minute dissection of 48 livers, we describe the territories of the left/right portal veins, hepatic ducts and hepatic arteries in the dorsal liver. In the caudate lobe, the right hepatic artery, rather than the left hepatic artery (23/48 vs 19/48 for right vs left, respectively), tended to supply the 'left' portal vein territory. Similarly, paradoxical drainage patterns, such as the right hepatic duct draining the left portal vein territory, were found in seven of 48 livers. In the territory of the hilar bifurcation, right hepatic artery dominance was also evident and various bile drainage patterns were found. These included double drainage by the bilateral hepatic ducts (3/48) and drainage into the confluence of bilateral ducts (6/48). In contrast, the arterial supply and biliary drainage of the paracavally located parenchyme of segments 7 and 8 usually depended on the proper segmental arteries and ducts and their variations were within the range of those found in other parts of the right lobe. Therefore, the dorsal liver concept may not be anatomical but, rather, simply aimed at usefulness in surgery. Nevertheless, clear subdivision of the caudate lobe according to biliary drainage and/or arterial supply seemed difficult because of the paradoxical relatioships among the portal vein, hepatic artery and bile duct. Consequently, the present results support extended surgery based on the dorsal liver concept for carcinomas involving the caudate lobe.     

Effect of benz(a)pyrene and constant light exposure on rat liver lysosomes and biliary excretion of lysosomal enzymes

Threefold administration of benz(a)pyrene in a dose of 20 mg/kg markedly stimulated biliary excretion of lysosomal enzymes from rat liver without signs of lysosomal damage. Constant light exposure induced changes attesting to functional activation of the lysosomal apparatus in liver cells and inhibited constitutive biliary excretion of lysosomal enzymes. Combined treatment decreased, but not abolished the stimulatory effect of benz(a)pyrene on vesicular transport of lysosomal enzymes to the bile.__________This revised version was published online in August 2005 with the addition of the issue titleTranslated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 139, No. 1, pp. 40–43, January, 2005     

The role of E. coli infection in the pathogenesis of primary biliary cirrhosis

Among various infectious agents possibly involved in the pathogenesis of primary biliary cirrhosis (PBC), Escherichia Coli (E. coli) has received special attention because of epidemiological and experimental evidence linking this bacterium with the disease's development. This review discusses early and more recent epidemiological studies associating recurrent urinary tract infections with E. coli and the development of PBC. We also critically review data provided over the years demonstrating disease-specific humoral and cellular immune responses against E. coli antigens in patients with PBC. Finally, we assess the relevance of experimental findings reporting cross-reactive immunity between mimicking sequences of E. coli and the major PBC mitochondrial antigens in the pathogenesis of the PBC. We also address the extent to which molecular mimicry and immunological cross-reactivity can be considered as a critical pathogenic process linking infection with self destruction.     

Regulation of murine acid secretion by CO2

To determine whether endogenous metabolic sources alone provide sufficient CO₂ for acid secretion in mammals, basal and stimulated acid secretion and metabolic CO₂ production were measured concurrently in mouse stomachs, in vitro, without exogenous CO₂, and after addition of 5% CO₂ serosally. Basal acid secretion was varied by changing luminal pH from 3.2 to 4.0. In the absence of an exogenous supply of CO₂ acid secretion was stable under basal conditions and increased during cholinergic stimulation with carbachol. Serosal CO₂ supply increased basal and stimulated acid secretion. The increase in basal acid secretion depended on the initial level of acid secretion. At pH 4.0, exogenous CO₂ increased acid output (mean±SD) by 13% from 112±11 nmol/min to 126±8 nmol/min (P<0.03), whereas at pH 3.6 the increase was 40% (63±14 to 88±20 nmol/min, P<0.04) and 157% at pH 3.2 (21±13 to 54±14 nmol/min, P<0.002). Following cholinergic stimulation a maximal acid output of 321±38 nmol/min was attained without serosal CO₂, whilst addition of 5% CO₂ to the serosal solution increased maximal acid secretion by 49% to 479±96 nmol/min (P<0.005). Metabolic activity, measured as total gastric CO₂ production, was greater as acid secretion rates increased [239±20 nmol/min at 21±13 nmol/min (luminal pH 3.2) versus 406±28 nmol/min at 321±17 nmol/min (after cholinergic stimulation)]. The data support the concept that basal and submaximal acid secretion can be maintained by CO₂ available from metabolic sources, but full expression of the acid secretory apparatus requires exogenous CO₂.     

A Case of Vanishing Bile Duct Syndrome after Drug-Induced Liver Injury Caused by Pelubiprofen

Vanishing bile duct syndrome (VBDS) is a rare disease characterized by ductopenia and cholestasis, and is linked to immunological damage to the bile duct system. VBDS can be triggered by infection, ischemia, autoimmune diseases, adverse drug reactions, and humoral factors associated with malignancy. A few cases of VBDS associated with nonsteroidal anti-inflammatory drug-related drug-induced liver injury (DILI) have been reported. Here, we report a case of a 29-year-old patient who developed DILI that progressed to VBDS after the administration of pelubiprofen.     

Medical treatment of primary biliary cirrhosis and primary sclerosing cholangitis

Chronic cholestasis is the main feature of primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC), the most common chronic cholestatic liver diseases in adults. Although the etiology of both diseases remains poorly understood, auto-immune processes appear to be important, particularly in PBC. PBC and PSC usually slowly progress to cirrhosis, liver failure, and death, unless liver transplantation is performed. Ursodeoxycholic acid (UDCA), a hydrophilic dihydroxy bile acid, is the only drug currently approved for the treatment of patients with PBC and is also used in patients with PSC. In addition to UDCA, patients with PSC should be referred to endoscopic dilatation of major bile duct stenoses. Several potential mechanisms of action of UDCA have been proposed, including intracellular modulation of signaling events and secretion. Various immunosuppressive drugs have been evaluated alone or in combination with UDCA—especially for the treatment of PBC. Of these drugs, the topical corticosteroid budesonide, together with UDCA, appears promising in the treatment of early stage PBC, but data remain insufficient to warrant use of budesonide outside of controlled studies.     

Regulation of calcitonin and parathyroid hormone secretion by oestrogens

Calcitonin is a peptide hormone secreted by C-cells which, in humans, are found mainly in the thyroid gland. It now seems that a major physiological function of this hormone in man is the long-term maintenance of the skeleton achieved by control of bone resorption. A marked sex difference in circulating calcitonin levels normally exists, with a relative deficiency in women as compared to men.It has now been found that oestrogens regulate calcitonin secretion and it appears likely that the loss of ovarian function at the menopause accelerates the natural decline in calcitonin secretion which occurs with age. Thus, post-menopausal women are more markedly calcitonin-deficient.Levels of the bone-resorbing hormones, parathyroid hormone (PTH) and 1,25 dihydroxyvitamin D are not elevated post-menopausally and it seems likely that the increased bone resorption which leads to post-menopausal bone loss is due mainly to the loss of oestrogen and calcitonin secretion.     

Optimizing biliary stent patency by coating with hydrophobin alone or hydrophobin and antibiotics or heparin: an in vitro proof of principle study

PurposeAlthough a wide range of biliary plastic and metal stents is on offer nowadays, the ideal cost-effective stent that functions permanently and that is easy to handle regarding its exchange is still not available. Therefore we tested in an in vitro model if the coating of plastic stents with hydrophobin alone or with hydrophobin and antibiotics or heparin in combination leads to an inhibition of the clogging process.MethodsWe coated commercially available biliary plastic stents with hydrophobin alone, as well as with hydrophobin and antibiotics or heparin in combination. After an incubation period of 28 days in human bile, we examined the stents by scanning electron microscopy to see whether the clogging material on its surface was reduced.ResultsCoating of plastic stents with hydrophobin led to a reduction in the amount of adherent material on the surface of the stents. Coupling of ampicillin/sulbactam or levofloxacin did not lead to a further reduction of the clogging material, whereas coupling with highly concentrated heparin did reduce the adherent material.ConclusionsThe coating of biliary plastic stents with hydrophobin or with hydrophobin and heparin in combination seems to be a promising option to delay the clogging process.     

Regulation of dendritic cell interleukin-12 secretion by tumour cell necrosis

Dendritic cells (DCs) play a key role in the induction and regulation of antigen-specific immunity. Studies have shown that, similar to infection, cellular necrosis can stimulate DC maturation. However, the ability of necrotic cell death to modulate DC cytokine secretion has yet to be explored. We investigated the regulation of interleukin (IL)-12 secretion by human DCs in response to tumour cell necrosis in an in vitro culture model. Two human tumour cell lines (K562 and JAr) were induced to undergo necrosis using heat injury and repeated cycles of freezing and thawing. Both types of tumour cells tested in this study, when injured, induced secretion of monomeric IL-12p40 by monocyte-derived DCs. Furthermore, priming DCs with necrotic cells augmented IL-12p70 secretion significantly in conjunction with CD40 cross-linking. This was physiologically relevant because cell death-pulsed DCs were more potent than non-pulsed DCs at stimulating T cells to proliferate and secrete interferon (IFN)-gamma. The Toll-like receptor 4 (TLR4) played a role in mediating the DC response to heat-killed, but not freeze/thaw-killed necrotic cells. For both methods of injury, proteins contributed to the effect of necrosis on dendritic cells, whereas DNA was involved in the effect of freeze/thawed cells only. These findings indicate that necrotic tumour cell death is not sufficient to induce bioactive IL-12p70, the Th1 promoting cytokine, but acts to augment its secretion via the CD40/CD40L pathway. The results also highlight that the mode of cell death may determine the mechanism of dendritic cell stimulation.