TIPS geometry influences patency.

OBJECTIVE: The purpose of this study was to evaluate potential causes of Transjugular intrahepatic portosystemic shunt (TIPS) dysfunction. MATERIAL AND METHODS: We retrospectively evaluated 26 patients who required TIPS revision (group I) and 24 patients who did not require any further intervention (group II) within the first two years following TIPS implantation. The distance of the distal end of the stent to the hepatocaval junction was measured. Furthermore, the angle between the stent and the portal vein (inflow) and the angle between the stent and the hepatic vein (outflow) were measured. Furthermore, the following data were evaluated: pre- and postinterventional portal pressure gradients, maximal postinterventional flow and blood values [C-reactive protein (CRP), bilirubin, glutamic-oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT)]. RESULTS: Compared with control subjects, patients who required TIPS revision showed a significantly longer distance from the distal end of the stent to the hepatocaval junction (I: 17.3 ±â€Š10 mm, II: 6.7 ±â€Š5.7 mm, p < 0.001). There was a statistically significant correlation between the above named distance and the time to revision (Pearson's correlation coefficient, r = 0.5, p = 0.01). In addition, patients with TIPS revision had a significantly larger angle of portalvenous inflow (alpha angle) than the control group (I: 100.5 ±â€Š31.5°, II: 64.5 ±â€Š31.6°, p < 0.001). CONCLUSION: Our results show that the distance from the end of the stent to the hepatocaval junction and the angle of portalvenous inflow are technical factors that may influence the shunt's patency rate. Of these two, the distance to the hepatocaval junction can be influenced easily by the interventionalist.

Intrahepatic type II gall bladder perforation by a gall stone in a CAPD patient.

INTRODUCTION: Perforation of the gall bladder represents a rare, but life-threatening complication of cholecystitis. Clinical presentation may vary between severe peritonism in acute perforation and absence of symptoms in subacute or chronic progression of perforation. Abdominal imaging like ultrasound or CT-scan are important tools for immediate diagnose of gall bladder perforation. CASE PRESENTATION: We report a case of a 30-year old female patient with end-stage kidney disease treated by continuous ambulatory peritoneal dialysis (CAPD) who was admitted to the emergency room with fever and mild abdominal pain. A type II gall bladder perforation by a solitary gall stone with development of a liver abscess was detected by abdominal ultrasound. CONCLUSION: Gall bladder perforations are rare but have to be considered in patients with abdominal pain and fever. Abdominal ultrasound is a reliable tool to establish diagnosis.

[Increasing number and improved survival of patients with hepatocellular carcinoma from 1988 to 2007: data of a German university clinic]. / Zunahme und verbessertes Überleben des hepatozellulären Karzinoms im Zeitraum von 1988 - 2007: Daten einer deutschen Universitätsklinik.

BACKGROUND AND OBJECTIVES: Hepatocellular carcinoma (HCC) ranks sixth regarding prevalence and third regarding mortality among malignant tumours worldwide. The aim of the present study was to determine changes of clinical-epidemiological parameters and survival rates during two decades. PATIENTS AND METHODS: A total of 441 consecutive patients with HCC admitted to the University Clinic Düsseldorf between January 1988 and December 2007 were included. For comparison, this time period was divided into two decades (1988 - 1997 and 1998 - 2007). RESULTS: The number of newly diagnosed HCCs has tripled in the years 1998 - 2007 compared to the years 1988 - 1997. HCV-associated HCCs increased from 28 % in the years 1988 - 1997 to 38 % (p < 0.05) in the years 1998 - 2007. Tumour size, Okuda and BCLC stages decreased during the observation period (both p < 0.001 and p < 0.05). Median overall survival improved during the observation period from 6 [95 % CI: 4.83 - 7.17] to 9 months ]95 % CI: 7.31 - 10.69]; p < 0.0001) as did the 1-year and 5-year survival rates from 22 % to 42 % (p < 0.019) and from 0 % to 9 % (p < 0.001), respectively. The proportion of treated patients compared to patients with best supportive care as well as the proportion of patients receiving a multimodal therapy compared to patients with a single treatment regimen increased in the second decade (55 % vs. 79 %: p < 0.005; 5.4 % vs. 23 %: p < 0.0001). Multimodal therapy was an independent predictor for prolonged survival in a multivariate analysis including Child-Pugh score, BCLC stage, tumour size, and gender (odds ratio 2,77; 95 % CI: 1.44 - 5.31). CONCLUSION: Improved screening as well as broader and improved treatment options may have contributed to the increasing survival rates.

[Diagnosis of focal liver lesions in cirrhotic patients: comparison of contrast-enhanced ultrasound using sulphur hexafluoride (SF6) microbubbles and MRI using Gd-EOB-DTPA]. / Vergleich der kontrastverstärkten Sonografie und der MRT mit Gd-EOB-DTPA zur Diagnostik fokaler Leberläsionen bei Patienten mit Leberzirrhose.

AIM: The diagnostic accuracies of contrast-enhanced sonography and hepatobiliary contrast-enhanced MRI of the liver in evaluating focal liver lesions in patients with liver cirrhosis were compared. MATERIAL AND METHODS: In 33 patients (25 men, 8 women, mean age 63.2 ± 11.2 years) MRI of the liver using Gd-EOB-DTPA (Primovist®, Bayer Schering Pharma, Berlin) was performed. Axial T(2)-weighted, unenhanced T(1)-weighted and enhanced T(1)-weighted scans during arterial, portal venous and late phases were acquired, followed by coronary T(1)-weighted and axial fat-suppressed T(1)-weighted scans 15 minutes post contrast application. In all patients within 4 weeks contrast-enhanced sonography using sulfur hexafluoride microbubbles (SonoVue®, Nycomed, Germany) was obtained. RESULTS: Cirrhosis of the liver was related to viral infection in 45.4% and to alcoholism in 39.4%. All hepatic lesions were confirmed by histologic examination. Sensitivity and specificity of MRI were 90.2% and 83.3%, compared to contrast-enhanced sonography with 92.7 % and 50 %, respectively. Positive and negative predictive values were 97.4% and 55.5 % for MRI and 90.5% and 50% for contrast-enhanced sonography, respectively. DISCUSSION: In this retrospective study MRI using Gd-EOB-DTPA as well as contrast-enhanced sonography using sulfur hexafluoride microbubbles gave excellent results in detecting HCC in patients suffering from liver cirrhosis. Although the specificity was higher for MRI, the accuracy showed no significant difference between these two imaging techniques.

Cholestatic liver diseases from child to adult: the diversity of MDR3 disease.

The phospholipidfloppase MDR3 (gene symbol: ABCB4) is expressed in the canalicular membrane of hepatocytes and mediates the biliary excretion of phosphatidylcholine, which is required for the formation of mixed micelles in bile. Several mutations of ABCB4 have been identified, which cause cholestatic liver diseases of varying severity including progressive familial intrahepatic cholestasis type 3 (PFIC-3), intrahepatic cholestasis of pregnancy (ICP) and the low phospholipid associated cholelithiasis syndrome (LPAC). Here, we report on four new (S1076N; L 23Hfs16X; c.286 + 1G > A; Q 1181E) and one known (S27G) MDR3 mutations in eight patients of three families. The patients presented with a wide spectrum of liver diseases. The clinical presentation and decisive laboratory findings or the association to a trend-setting family history led to the identification of the genetic background in these patients. Even the same mutation may be associated with varying disease progression.

Contribution of variant alleles of ABCB11 to susceptibility to intrahepatic cholestasis of pregnancy.

BACKGROUND: Intrahepatic cholestasis of pregnancy (ICP) has a complex aetiology with a significant genetic component. ABCB11 encodes the bile salt export pump (BSEP); mutations cause a spectrum of cholestatic disease, and are implicated in the aetiology of ICP. METHODS: ABCB11 variation in ICP was investigated by screening for five mutant alleles (E297G, D482G, N591S, D676Y and G855R) and the V444A polymorphism (c.1331T>C, rs2287622) in two ICP cohorts (n = 333 UK, n = 158 continental Europe), and controls (n = 261) for V444A. PCR primers were used to amplify and sequence patient and control DNA. The molecular basis for the observed phenotypes was investigated in silico by analysing the equivalent residues in the structure of the homologous bacterial transporter Sav1866. RESULTS: E297G was observed four times and D482G once. N591S was present in two patients; D676Y and G855R were not observed. The V444A polymorphism was associated with ICP (allelic analysis for C vs T: OR 1.7 (95% CI 1.4 to 2.1, p<0.001)). In addition, CC homozygotes were more likely to have ICP than TT homozygotes: OR 2.8 (95% CI 1.7 to 4.4 p<0.0001). Structural analyses suggest that E297G and D482G destabilize the protein fold of BSEP. The molecular basis of V444A and N591S was not apparent from the Sav1866 structure. CONCLUSIONS: Heterozygosity for the common ABCB11 mutations accounts for 1% of European ICP cases; these two mutants probably reduce the folding efficiency of BSEP. N591S is a recurrent mutation; however, the mechanism may be independent of protein stability or function. The V444A polymorphism is a significant risk factor for ICP in this population.

Expression in human trophoblast and choriocarcinoma cell lines, BeWo, Jeg-3 and JAr of genes involved in the hepatobiliary-like excretory function of the placenta.

Using cytokeratin-7-positive trophoblast cells (hTr) isolated from human term placentas and the choriocarcinoma cell lines (hCC) BeWo, Jeg-3 and JAr, the expression of genes involved in the hepatobiliary excretion of cholephilic compounds was investigated by RT-PCR/sequencing followed by measurement of the absolute abundance of mRNA by real-time RT-PCR. Although mRNA of BSEP was detectable and its expression confirmed by Western blotting, its very low expression (higher in hTr than in whole placenta and hCC) did not permit its detection by immunohistochemistry. In hTr, the expression was high for OATP-B/2B1, OATP-8/1B3, MRP1, MRP3, BCRP, FIC1, RARalpha, FXR and SHP, low for OSTalpha, MRP2, MRP4, MRP8, MDR1, CAR and SXR, very low for OATP-A/1A2 and MDR3, and not detectable for OATP-C/1B1, HNF1alpha and HNF4. Expression patterns in hCC mimicked those in hTr, although some important cell line-specific differences were found. The functionality of transporters expressed in hCC was confirmed by their ability to take up and export estradiol 17beta-d-glucuronide in a self-inhibitable and temperature-sensitive manner. In conclusion, several transporters, export pumps, and nuclear receptors involved in the liver excretory function may play a similar role in the placenta, whose specific aspects can be studied by selectively using BeWo, Jeg-3 or JAr cells.

Recurrence of Progressive Familial Intrahepatic Cholestasis Type 2 Phenotype After Living-donor Liver Transplantation: A Case Report.

BACKGROUND: Progressive familial intrahepatic cholestasis 2 (PFIC2) is the result of mutations in the ABCB11, which encodes for bile salt export pump (BSEP). An absence of BSEP in the canalicular membrane causes cholestasis and leads to the development of end-stage liver disease in the first decade of life. Liver transplantation (LT) has been considered curative for BSEP disease. However, patients with PFIC2 having undergone LT have recently been reported to develop recurrence of cholestasis together with the clinical and histological features of primary BSEP disease. CASE REPORT: We herein present a rare case of a patient with PFIC2 who developed post-transplantation recurrence of progressive intrahepatic cholestasis due to antibodies against BSEP after living-donor LT, which mimicked primary BSEP disease. The patient had mutations in the ABCB11 gene, resulting in the complete absence of BSEP in the native liver, explaining the lack of tolerance. Immunofluorescence staining of normal human liver sections with the patient's serum and using an anti-human immunoglobulin G antibody to detect serum antibodies showed reactivity to the BSEP epitope in the canalicular membrane. We suggest that the patients having undergone LT had been associated with a risk of autoantibody formation against the BSEP protein. The absence of primary tolerance for the BSEP epitopes may explain the formation of the anti-BSEP antibodies after LDLT.

Osmosignalling in C6 glioma cells.

The influence of aniso-osmolarity on the activity of the MAP kinases Erk-1 and Erk-2 was studied in C6 glioma cells. Hypo-osmotic treatment (205 mosmol/l) led to an increased activity of Erk-1 and Erk-2 within 3 min, which became maximal at 10 min and returned to basal level within 120 min. In contrast, Erk activity was reduced under hyper-osmotic conditions (405 mosmol/l), compared to the normo-osmotic control (305 mosmol/l). Erk activation was accompanied by a mobility shift of Raf-1. Hypo-osmotic exposure increased the cytosolic Ca2+ concentration ([Ca2+]i). Absence of extracellular Ca2+ largely abolished the [Ca2+]i response to hypo-osmolarity, whereas Erk activation following hypo-osmotic stimulation remained unaffected, suggesting a Ca2+ independence of the osmosignalling pathway to the MAP kinases. Both the Ca2+ response as well as the Erk activation following hypo-osmotic exposure were maintained in the presence of the phospholipase C inhibitor U73122. Application of 8-CPT cAMP, forskolin/isobutylmethylxanthine or isoproterenol blocked Erk activation following hypo-osmotic treatment of the cells, suggesting a role of the Ras/Raf pathway upstream from Erk-1 and Erk-2. Protein kinase C (PKC) is unlikely to play a role in the hypo-osmolarity- induced signalling towards MAP kinases, as revealed by inhibition of PKC with Go6850. Inhibition of pertussis- or cholera toxin-sensitive G-proteins as well as inhibition of tyrosine kinases with genistein and of PI3 kinase by wortmannin had no effect on the Erk response to hypo-osmolarity. It is concluded that osmosignalling in C6 glioma cells differs upstream of the MAP kinases from that observed in primary rat astrocytes, H4IIE rat hepatoma cells and isolated rat hepatocytes.

Expression of glutamine synthetase in macrophages.

We studied the expression of glutamine synthetase in liver macrophages (Kupffer cells, KCs) in situ and in culture. Glutamine synthetase was detectable at the mRNA and protein level in freshly isolated and short-term-cultured rat liver macrophages. Enzyme activity and protein content were about 9% of that in liver parenchymal cells. In contrast, glutamine synthetase mRNA levels in liver macrophages apparently exceeded those in parenchymal liver cells (PCs). By use of confocal laser scanning microscopy and specific macrophage markers, immunoreactive glutamine synthetase was localized to macrophages in normal rat liver and normal human liver in situ. All liver macrophages stained positive for glutamine synthetase. In addition, macrophages in rat pancreas contained immunoreactive glutamine synthetase, whereas glutamine synthetase was not detectable at the mRNA and protein level in blood monocytes and RAW 264.7 mouse macrophages. No significant amounts of glutamine synthetase were found in isolated rat liver sinusoidal endothelial cells (SECs). The data suggest a constitutive expression of glutamine synthetase not only, as previously believed, in perivenous liver parenchymal cells but also in resident liver macrophages.

Effect of maternal cholestasis on TGR5 expression in human and rat placenta at term.

BACKGROUND & AIMS: TGR5 (Gpbar-1) is a plasma membrane-bound bile acid receptor expressed in several tissues, including liver, intestine and brain. High levels of TGR5 mRNA have been detected in human and rodent placenta, however, localization of the TGR5 protein has not been studied in this tissue. We aimed at characterizing TGR5 expression in placental tissue and investigated the effect of bile acids and progesterone metabolites, which accumulate during intrahepatic cholestasis of pregnancy (ICP), on receptor expression and localization. METHODS: TGR5 mRNA levels and cell-specific localization were determined by quantitative PCR and immunofluorescence, respectively. RESULTS: In human term placentas, TGR5 was mainly localized in fetal macrophages and to a lower extent in trophoblasts. In placentas from ICP patients and pregnant rats with obstructive cholestasis a marked down-regulation of TGR5 mRNA expression was observed. However, the cell-specific distribution of the TGR5 protein was unaffected. Besides bile acids, progesterone and its metabolites (5α-pregnan-3α-ol-20-one/5α-pregnan-3ß-ol-20-one), which increase in serum during ICP, were able to dose-dependently activate TGR5. In addition, progesterone metabolites but not their sulfated derivatives nor taurolithocholic acid, significantly down-regulated TGR5 mRNA and protein expression in isolated human macrophages and a macrophage-derived cell line. CONCLUSION: Since fetal macrophages and trophoblast cells are exposed to changes in the flux of compounds across the placental barrier, the expression of TGR5 in these cells together with its sensitivity to bile acids and progesterone metabolites regarding receptor activity and mRNA expression suggest that TGR5 may play a role in the effect of maternal cholestasis on the placenta.

Multiple liver abscesses with isolation of Streptococcus intermedius related to a pyogenic dental infection in an immuno-competent patient.

INTRODUCTION: Streptococcus intermedius - a member of the Streptococcus anginosus group - is part of the normal microbial flora of the oral cavity. Despite being regarded as a harmless apathogenic commensal, Streptococcus intermedius has been described to cause abscesses in various locations of the body. CASE PRESENTATION: We report the clinical case and course of treatment of a 18-year-old male patient presenting with multiple hepatic abscesses associated with an untreated pyogenic dental infection. CONCLUSION: Streptococcus intermedius can cause liver abscesses emerging from dental infectious foci even in previously healthy patients without underlying innate or aquired immunodeficiency. The case illustrates the potential danger and underestimated risk associated with untreated dental infections.

Symptomatic separation of the pubic symphysis.

We present seven cases of pubic symphyseal discomfort in pregnancy or parturition. These patients were unable to walk and had other signs and symptoms similar to those of osteitis pubis. We differentiate this condition from classical osteitis pubis by the lack of a prolonged course, symptoms, and clinical findings rather than radiologic criteria. We propose that in patients with symphyseal pain and tenderness, difficulty with ambulation, and a clinical course of less than three weeks, symptomatic symphyseal separation should be considered the diagnosis.

Regulation of the multidrug resistance protein 2 in the rat liver by lipopolysaccharide and dexamethasone.

BACKGROUND & AIMS: Endotoxin lipopolysaccharide (LPS) induces cholestasis and down-regulates the multidrug resistance protein 2 (MRP2). This study intends to characterize the short-term effects of LPS on MRP2. METHODS: The effects of LPS and dexamethasone on excretion of bromosulphalein (BSP), MRP2 messenger RNA (mRNA) levels, and subcellular MRP2 localization were studied by means of liver perfusion, Northern blots, and confocal microscopy. RESULTS: LPS treatment for 3-12 hours decreased biliary BSP excretion (10 micromol/L) by 40%. Hyposmolarity stimulated BSP excretion to control levels 3 hours after LPS injection, but was ineffective after 12 hours or in saline-treated controls. LPS led to a strong decrease of MRP2 mRNA after 12 hours, but not during the first 6 hours. LPS induced the appearance of MRP2 in intracellular vesicles in the immediate vicinity of the canaliculi within 3 hours, and these vesicles were remote from the canaliculi after 6 and 12 hours. The MRP2-containing vesicles did not stain for dipeptidylpeptidase IV (DPPIV). Dexamethasone counteracted the LPS effects on MRP2 mRNA levels, subcellular distribution, and BSP excretion. CONCLUSIONS: LPS induces cholestasis due to an early retrieval of MRP2 from the canalicular membrane, whereas down-regulation of MRP2 mRNA is a later event. LPS-induced MRP2 retrieval from the canalicular membrane is not associated with the retrieval of DPPIV, suggestive for selectivity of the process.

Osmodependent dynamic localization of the multidrug resistance protein 2 in the rat hepatocyte canalicular membrane.

BACKGROUND & AIMS: Circumstantial evidence suggests a regulation of biliary secretion by transporter insertion and retrieval into and from the canalicular membrane. This study was undertaken to provide direct evidence for such a process. METHODS: Osmosensitivity of the subcellular localization of the mrp2 gene-encoded conjugate export pump (MRP2) was studied by immunofluorescence and confocal laser scanning microscopy of isolated hepatocyte aggregates and in perfused rat liver. RESULTS: MRP2 was localized largely in membranes of the pseudocanaliculi formed by isolated hepatocyte aggregates during hypo-osmotic exposure, whereas after hyperosmotic exposure MRP2 was also detectable in intracellular vesicles. In perfused liver, the EAG15 antibody specific for rat MRP2 and the ZO-1 antibody specific for tight junctions produced immunostaining of the canalicular membrane. However, the relative amount of MRP2 increased significantly in the pericanalicular region with increasing perfusate osmolarity, as shown by confocal microscopy of intracellular vesicles containing MRP2 (but not ZO-1) and by computed densitometry. The osmodependent distribution of MRP2 between the canalicular membrane and intracellular, pericanalicular vesicles occurred within 30 minutes and was fully reversible. CONCLUSIONS: The findings provide direct evidence for an osmosensitive dynamic insertion and retrieval of the canalicular MRP2 transporter into and out of the canalicular membrane.

Dexamethasone- and osmolarity-dependent expression of the multidrug-resistance protein 2 in cultured rat hepatocytes.

Expression of the conjugate export pump multidrug-resistance protein 2 (MRP2) in liver is regulated by endotoxin and anti-tumour agents. This paper reports on the effects of dexamethasone and osmolarity on MRP2 expression. MRP2 expression was studied at the protein, mRNA, immunocytochemical and functional levels in cultured rat hepatocytes. Protein and mRNA expression of MRP2 in rat hepatocytes 24 and 48 h after isolation were largely dependent on the presence of dexamethasone (100 nmol/l) in the culture medium. MRP2 was localized at the pseudocanalicular membrane and increased expression of MRP2 was accompanied by a widening of the pseudocanaliculi. In presence of dexamethasone, hypo-osmolarity (205 mosmol/l) led to a strong induction of MRP2 mRNA and protein, whereas expression was decreased by hyperosmolarity (405 mosmol/l). Also, a decay of MRP2 protein and mRNA following dexamethasone withdrawal was osmosensitive. Expression of dipeptidylpeptidase IV, another canalicular protein, was unaffected by dexamethasone and osmolarity. It is concluded that glucocorticoids are strong inducers of MRP2 in liver. Besides short-term carrier insertion/retrieval, osmoregulation of MRP2 also involves a long-term effect on MRP2 expression.

cAMP-dependent activation of small-conductance Cl- channels in HT29 colon carcinoma cells.

The present study was performed to examine the conductance properties in the colon carcinoma cell line HT29 and the activation of Cl- channels by cAMP. A modified cell-attached nystatin patch-clamp technique was used, allowing for the simultaneous recording of the cell membrane potential (PD) and the conductance properties of the cell-attached membrane. In resting cells, PD was -56 +/- 0.4 mV (n = 294). Changing the respective ion concentrations in the bath indicate that these cells possess a dominating K+ conductance and a smaller Cl- conductance. A significant non-selective cation conductance, which could not be inhibited by amiloride, was only observed in cells examined early after plating. The K+ conductance was reversibly inhibited by 1 - 5 mmol/l Ba2+. Stimulation of the cells by the secretagogues isoproterenol and vasointestinal polypeptide (VIP) depolarized PD and induced a Cl- conductance. Similar results were obtained with compounds increasing cytosolic cAMP: forskolin, 3-isobutyl-1-methylxanthine, cholera toxin and 8-bromoadenosine cyclic 3',5'-monophosphate (8-Br-cAMP). VIP (1 nmol/l, n = 10) and isoproterenol (1 mumol/l, n = 12) depolarized the cells dose-dependently and reversibly by 12 +/- 2 mV and 13 +/- 2 mV. The maximal depolarization was reached after some 20 s. The depolarization was due to increases in the fractional Cl- conductance. Simultaneously the conductance of the cell-attached membrane increased from 155 +/- 31 pS to 253 +/- 40 pS (VIP, n = 4) and from 170 +/- 43 pS to 268 +/- 56 pS (isoproterenol, n = 11), reflecting the gating of Cl- channels in the cell-attached membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Short-term regulation of canalicular transport.

On a short term basis, canalicular secretion is under control of the hepatocellular hydration state, substrates, cytokines, toxins, and hormones. Regulation occurs at the level of substrate availability, covalent modification of transporters, and their regulated exocytic insertion into or endocytic retrieval from the membrane. A variety of signal transduction pathways involving the activation of mitogen-activated protein kinases, protein kinases A and C, participates in these processes. However, much has still to be learned about the crosstalk of different signaling systems and their molecular targets that determine the outcome for canalicular secretion.

Small and intermediate conductance chloride channels in HT29 cells.

Recently, it has been shown that intermediate conductance outwardly rectifying chloride channels (ICOR) are blocked by cytosolic inhibitor (C. I.) found in the cytosol of human placenta and epithelial cells. C. I. also reduced the baseline current in excised membrane patches of HT29 cells. In the present study, this effect of C. I. was characterized further. Heat treated human placental cytosol was extracted in organic solvents and dissolved in different electrolyte solutions. It is shown that the reduction of baseline conductance (g(o)) is caused by inhibition of small non-resolvable channels, which are impermeable to Na+ and SO4(2-), but permeable to Cl-. The regulation of these small Cl(-)-conducting channels (g(o)) and of ICOR was examined further. First, no activating effects of protein kinase A (PKA) on the open probability (Po) of the ICOR or on the g(o)) were observed. The Po of the ICOR was reduced by 22% in a Ca(2+)-free solution. g(o) was insensitive to changes in the Ca2+ activity. The effects of C. I. from a cystic fibrosis (CF) placenta and the CF pancreatic duct cell line CFPAC-1 were compared with the effects of corresponding control cytosols, and no significant differences between CF and control cytosols were found. We conclude that the excised patches of HT29 cells contain ICOR and small non-resolvable Cl(-)-conducting channels which are similarly inhibited by C. I.(ABSTRACT TRUNCATED AT 250 WORDS)