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P Olinga

Publications and source records attributed to P Olinga.

At least 19 recordsLinked to original sources
PubMed2006

Human liver slices as an in vitro model to study toxicity-induced hepatic stellate cell activation in a multicellular milieu.

INTRODUCTION: Hepatic stellate cell (HSC) activation is a key event in wound healing as well as in fibrosis development in the liver. Previously we developed a technique to induce HSC activation in slices from rat liver. Although this model provides a physiologic, multicellular milieu that is not present in current in vitro models it might still be of limited predictive value for the human situation due to species-differences. Therefore, we now aimed to evaluate the applicability of human liver slices for the study of HSC activation. METHOD: Liver slices (8 mm diameter, 250 microm thickness) were generated from human liver tissue and incubated for 3 or 16 h with 0-15 microl of carbon tetrachloride (CCl4) after which ATP-content and expression levels of HSC (activation) markers was determined. RESULTS: Human liver slices remained viable during incubation as shown by constant ATP levels. Incubation with CCl(4) caused a dose-dependent decrease in viability and an increase in mRNA expression of the early HSC activation markers HSP47 and alphaB-crystallin, but not the late markers for HSC activation, alphaSMA and pro-collagen 1a1. Synaptophysin mRNA expression remained constant during incubation with or without CCl4, indicating a constant number of HSC in the liver slices. CONCLUSION: We developed a technique to induce early toxicity-induced HSC activation in human liver slices. This in vitro model provides a multicellular, physiologic milieu to study mechanisms underlying toxicity-induced HSC activation in human liver tissue.

Carbon Tetrachloride↗
PubMed2006

An ex vivo human model system to evaluate specificity of replicating and non-replicating gene therapy agents.

BACKGROUND: Inefficiency, aspecificity and toxicity of gene transfer vectors hamper gene therapy from showing its full potential. On this basis significant research currently focuses on developing vectors with improved infection and/or expression profiles. Screening assays with validity to the clinical context to determine improved characteristics of such agents are not readily available since this requires a close relationship to the human situation. We present a clinically relevant tissue slice technology to preclinically test improved vector characteristics. METHODS: Slices were prepared from rat, mouse and human liver samples and from tumor tissue. Specificity of gene expression and replication was determined by infecting target and non-target tissue slices with transcriptionally retargeted adenoviruses and oncolytic viruses. RESULTS: Using rat liver slices, we demonstrate efficient knob-mediated adenoviral infectivity. A favorable tumor-on/liver-off profile, resembling in vitro and mouse in vivo data, was shown for a tumor-specific transcriptionally retargeted adenovirus by infecting slices prepared from tumor or liver tissue. Similar liver-off data were found for mouse, rat and human samples (over 3-log lower activity of the tumor-specific promoter compared to cytomegalovirus (CMV)). More importantly, we show that this technology when applied to human livers is a powerful tool to determine aspecific replication of oncolytic viruses in liver tissue. A 2- to 6-log reduction in viral replication was observed for a tumor-specific oncolytic virus compared to the wild-type adenovirus. CONCLUSIONS: The precision-cut tissue slice technology is a powerful method to test specificity and efficiency of gene transfer as well as of viral replication using human tissue.

Adenoviridae↗
PubMed2002

Drug-metabolizing activity of human and rat liver, lung, kidney and intestine slices.

1. Organ-specific biotransformation was studied in human and rat liver, lung, kidney and small intestine slices and compared on a protein basis, using four model substances. 2. Deethylation of lidocaine was highest in liver slices from both man and rat, followed by the small intestine. 3. Metabolism of testosterone was highest in liver slices, but a different overall metabolic pattern was found between the different organs. 4. Lung, kidney and intestine slices prepared from human and rat organs showed mainly an unknown metabolite of 7-ethoxycoumarin identified as 4-ethoxy-2-hydroxyphenyl propionic acid (EPPA). 5. The maximal metabolism of 7-ethoxycoumarin in slices was equal with in vivo V(max) in the rat. 6. Phase II metabolism of 7-hydroxycoumarin in kidney and intestinal slices was about 60% of the activity in liver slices. 7. In conclusion, organs other than the liver show a surprisingly high drug-metabolizing activity. Thus, the use of precision-cut slices of a combination of drug metabolizing organs in an in vitro test system from both animal and human origin is required for a proper systematic prediction of drug metabolism in man.

Adenosine Triphosphate↗
PubMed2001

Cytomegalovirus infection increases the expression and activity of ecto-ATPase (CD39) and ecto-5'nucleotidase (CD73) on endothelial cells.

We describe enhanced expression and enzymatic activity of ecto-ATPase and ecto-5'nucleotidase on CMV infected endothelial cells as compared to uninfected cells. These ectoenzymes play a major role in modulation of platelet activation and aggregation. Furthermore, adenosine has a modulatory effect upon inflammation. Addition of ATP, ADP or AMP to cultures of CMV infected or uninfected endothelial cells revealed increased turnover of AMP in CMV infected endothelial cells. In addition, the superoxide production by stimulated polymorphonuclear cells was inhibited in the presence of CMV infected endothelial cells as compared to uninfected cells, probably due to the enhanced activity of ecto-5'nucleotidase and associated to production of adenosine.

5'-Nucleotidase↗
PubMed2001

Rat liver slices as a tool to study LPS-induced inflammatory response in the liver.

BACKGROUND/AIMS: Inflammation in the liver is a complex interaction between parenchymal and non-parenchymal cells, and therefore can not be studied in vitro in pure cultures of these cells. METHODS: We investigated whether Kupffer cells in the liver slice are still responsive to an inflammatory stimulus of lipopolysaccharide (LPS), and evoke an inflammatory response in the hepatocytes. RESULTS: TNFalpha, IL-1beta and IL-10 were significantly elevated in culture medium of LPS-stimulated rat liver slices. Nitric oxide (NO) production of LPS-treated slices gradually increased from 5 to 24 h (24 h: 81+/-5 microM vs. 14+/-2 microM in control P < 0.05), paralleled by inducible nitric oxide synthase (iNOS) in the hepatocytes, iNOS mRNA was induced after 3 h. NO production but not iNOS induction was significantly inhibited by NOS inhibitors S-methylisothiourea and N(G)-nitro-L-arginine methylester. Both pentoxifylline and dexamethasone inhibited TNFalpha and IL-1beta production, albeit to a different extent, iNOS induction and, as a result thereof, NO production. CONCLUSIONS: These results imply that non-parenchymal cells in liver slices are viable and can be activated by LPS. In addition, it is concluded that the upregulation of iNOS in hepatocytes by LPS is caused by cytokines produced by Kupffer cells because inhibition of TNFalpha and IL-1beta production attenuated iNOS induction.

Alanine Transaminase↗
PubMed2001

Characteristics of the hepatic stellate cell-selective carrier mannose 6-phosphate modified albumin (M6P(28)-HSA).

BACKGROUND/AIMS: Drug targeting to hepatic stellate cells (HSC) may improve the pharmacological effects of antifibrotic drugs. Recently, albumin substituted with 28 mannose 6-phosphate moieties (M6P(28)-HSA) was found to distribute selectively to HSC in fibrotic rat livers. To assess whether this albumin can be used as a carrier for intracellular drug delivery, we explored the cellular handling of M6P(28)-HSA in HSC. METHODS/RESULTS: Application of competitive substrates for the M6P/IGFII receptor or other receptors showed that the binding of M6P-HSA to the M6P/IGFII receptor is specific. Binding was strong to activated HSC, but not to quiescent HSC. Furthermore, M6P(28)-HSA was extensively internalized by these cells. Using monensin, a specific inhibitor of the lysosomal pathway, proof was obtained that M6P-HSA is endocytosed via this route. The experiments performed with tissue slices, prepared from rat and human livers, revealed a specific binding and uptake of M6P(28)-HSA in both normal and cirrhotic livers. In livers from cirrhotic patients, HSC contributed predominantly to the uptake of this neoglycoprotein. CONCLUSIONS: Based on our in vivo data demonstrating the HSC-selectivity and on our in vitro data demonstrating binding and rapid internalization in activated HSC, we conclude that M6P(28)-HSA is applicable as a stellate cell-selective carrier for antifibrotic drugs that act intracellularly. This may have implications for the design of new strategies for the treatment of liver fibrosis.

Animals↗
PubMed2001

Targeting dexamethasone to Kupffer cells: effects on liver inflammation and fibrosis in rats.

Kupffer cells (KC) play an important role in the pathogenesis of inflammatory liver diseases leading to fibrosis. Anti-inflammatory drugs are only effective when administered at high doses that may cause side effects. Therefore, dexamethasone coupled to mannosylated albumin (Dexa(5)-Man(10)-HSA) was designed by us to selectively deliver this anti-inflammatory drug to the KC. The effectiveness of Dexa(5)-Man(10)-HSA was studied both in organ cultures and fibrosis induced by bile duct ligation (BDL) in rats. Dexa(5)-Man(10)-HSA accumulated in livers of both healthy and fibrotic rats (67% +/- 5% and 70% +/- 9% of the dose, respectively) and uptake was found almost exclusively in KC. Active dexamethasone was liberated from its carrier, because Dexa(5)-Man(10)-HSA could effectively inhibit nitric oxide (NO) and tumor necrosis factor alpha (TNF-alpha) release in endotoxin-activated liver slices. In vivo, however, this was associated with increased collagen I and III depositions and enhanced tissue inhibitor of metalloproteinase-1 (TIMP-1) mRNA expression. This was accompanied by a decreased influx of reactive oxygen species (ROS) producing cells in the livers of BDL animals treated with Dexa(5)-Man(10)-HSA as compared with untreated BDL rats. Dexa(5)-Man(10)-HSA treatment also replenished the depleted glycogen stores in hepatocytes of BDL livers. In conclusion, our studies showed selective delivery of dexamethasone to KC with Dexa(5)-Man(10)-HSA. This conjugate reduced intrahepatic ROS in vivo and TNF-alpha production in vitro and prevented glycogen depletion in vivo, indicating effective pharmacologic targeting. Dexa(5)-Man(10)-HSA, however, also accelerated fibrogenesis, which was paralleled by TIMP-1 mRNA induction. Targeting of dexamethasone to KC provides evidence for a dual role of this cell type in fibrogenesis of BDL rats.

Animals↗
PubMed2001

Cellular distribution and handling of liver-targeting preparations in human livers studied by a liver lobe perfusion.

We developed and tested a novel method for perfusing parts of human liver to study uptake and handling of drug-targeting preparations. These preparations, designed for the treatment of liver fibrosis in man, have been extensively studied in animals, but little is known about the uptake and handling by human livers. Human liver tissue was obtained from livers procured from multiorgan donors and from cirrhotic livers of patients. To assess tissue viability, perfusate glutamate-oxalacetate-transaminase (GOT), glutamate-pyruvate-transaminase (GPT), and lactate dehydrogenase (LDH) levels were determined. To assess tissue functionality, the uptake of taurocholic acid and phase I and II metabolism of lidocaine and 7-hydroxycoumarin were determined. Uptake of a drug-targeting preparation was studied with Dexa10-HSA, which is designed for targeting of dexamethasone to nonparenchymal cells in the liver. During a 90-min perfusion period, no elevation of either GOT, GPT, or LDH was found. Both healthy control livers and cirrhotic livers showed phase I and II drug metabolism and functional taurocholic acid uptake. Studies with Dexa10-HSA revealed that 60 min after administration, 40% of the dose had been taken up by control livers and only 5% by cirrhotic livers. In control livers, Kupffer and endothelial cells had taken up Dexa10-HSA, whereas in cirrhotic livers only Kupffer cells were responsible for the uptake. Viability parameters and liver function tests clearly showed the applicability of this method. In the perfusion set-up, we showed uptake of the drug-targeting preparation Dexa10-HSA by healthy and cirrhotic human liver tissue, although the distribution patterns differed. This demonstrates the need to study new concepts in (diseased) human tissue.

Anesthetics, Local↗
PubMed2001

Cellular distribution and handling of liver-targeting preparations in human livers studied by a liver lobe perfusion.

We developed and tested a novel method for perfusing parts of human liver to study uptake and handling of drug-targeting preparations. These preparations, designed for the treatment of liver fibrosis in man, have been extensively studied in animals, but little is known about the uptake and handling by human livers. Human liver tissue was obtained from livers procured from multiorgan donors and from cirrhotic livers of patients. To assess tissue viability, perfusate glutamate-oxalacetate-transaminase (GOT), glutamate-pyruvate-transaminase (GPT), and lactate dehydrogenase (LDH) levels were determined. To assess tissue functionality, the uptake of taurocholic acid and phase I and II metabolism of lidocaine and 7-hydroxycoumarin were determined. Uptake of a drug-targeting preparation was studied with Dexa(10)-HSA, which is designed for targeting of dexamethasone to nonparenchymal cells in the liver. During a 90-min perfusion period, no elevation of either GOT, GPT, or LDH was found. Both healthy control livers and cirrhotic livers showed phase I and II drug metabolism and functional taurocholic acid uptake. Studies with Dexa(10)-HSA revealed that 60 min after administration, 40% of the dose had been taken up by control livers and only 5% by cirrhotic livers. In control livers, Kupffer and endothelial cells had taken up Dexa(10)-HSA, whereas in cirrhotic livers only Kupffer cells were responsible for the uptake. Viability parameters and liver function tests clearly showed the applicability of this method. In the perfusion set-up, we showed uptake of the drug-targeting preparation Dexa(10)-HSA by healthy and cirrhotic human liver tissue, although the distribution patterns differed. This demonstrates the need to study new concepts in (diseased) human tissue.

Anesthetics, Local↗
PubMed2000

Dexamethasone coupled to albumin is selectively taken up by rat nonparenchymal liver cells and attenuates LPS-induced activation of hepatic cells.

BACKGROUND/AIMS: The human serum albumin (HSA) conjugate Dexa10-HSA was designed to specifically deliver the anti-inflammatory drug dexamethasone (Dexa) to nonparenchymal cells (NPC) in the rat liver. NPC play an important role in the pathogenesis of acute and chronic inflammatory liver diseases like fibrosis. Targeting Dexa to these cells might reduce its adverse effects and increase the efficacy. METHODS: Tissue and intrahepatic distributions of Dexa10-HSA were assessed in normal and fibrotic rats with 125I-labelled conjugate and by immunohistochemistry. The effect of the conjugate on lipopolysaccharide (LPS)-induced inflammation and cell activation was studied in vitro with precision-cut liver slices and in vivo. RESULTS: Ten minutes after i.v. injection 72+/-13% and 65+/-12% of a tracer dose of Dexa10-HSA had been taken up in normal and fibrotic livers, respectively. Unconjugated Dexa also accumulated in livers, but cellular distribution studies revealed an accumulation in parenchymal cells (NPC vs. parenchymal cell (PC) ratio=0.29+/-11, p<0.005) whereas Dexa10-HSA accumulated in nonparenchymal cells (NPC/PC ratio=7.9+/-3.1). Both coupled and uncoupled Dexa showed effective inhibition of LPS-induced NOx and TNFalpha production in precision-cut liver slices. At low concentrations (0.02 microM), however, Dexa10-HSA was more efficient at inhibiting TNFalpha production than uncoupled Dexa. In fibrotic rats Dexa10-HSA (3 mg/kg) and an equimolar amount of uncoupled Dexa (0.22 mg/kg) both significantly promoted survival after LPS-induced acute inflammation. CONCLUSION: Dexa10-HSA was at least as effective as uncoupled Dexa at inhibiting LPS-induced effects, which indicates that HSA-bound Dexa is pharmacologically active. Coupling Dexa to HSA shifted the accumulation of Dexa from the PC to the NPC of livers. Since mediator release from NPC is crucial in the initiation and propagation of the fibrotic process, selective delivery of Dexa in NPC may improve the efficacy and safety of corticosteroid treatment of liver fibrosis.

Albumins↗
PubMed2000

The capability of isolated hepatocytes and liver slices of donor livers to predict graft function after liver transplantation.

AIMS/BACKGROUND: In liver transplantation, adequate function tests for donor livers and transplanted livers are of utmost importance to provide an objective basis for decision-making. Isolated hepatocyte and/or slice preparations from human donor liver tissue may be suitable to test the quality of the organ to be transplanted. METHODS: Surgical waste material remaining after reduced size or split liver transplantation in children was used to prepare slices and isolated hepatocytes. The viability of these preparations as well as drug transport and metabolism functions were determined and related to graft function in 32 liver recipients. RESULTS: The in vitro tests used in the present study apparently did not select non-viable livers. In vitro preparations of the primary non-function grafts which occurred in the investigated group showed normal viability, metabolic and uptake function. CONCLUSION: These results indicate that either the presently used viability tests are not sensitive enough to detect potential organ failure or that other factors besides the hepatocyte viability at the time of transplantation are of paramount importance to the graft function of the recipient, such as complications during and after transplantation or the viability of the non-parenchymal cells.

Adenosine Triphosphate↗
PubMed2000

Procalcitonin behaves as a fast responding acute phase protein in vivo and in vitro.

OBJECTIVES: Procalcitonin (PCT) is a 13 kD protein of which plasma concentrations are strongly increased in inflammatory states. PCT concentrations are claimed to have a more powerful discriminatory value for bacterial infection than the acute phase proteins serum amyloid A (SAA) or C-reactive protein (CRP). The source of production and its mechanism of induction are unknown. We investigated the inducibility of PCT both in vivo and in vitro and compared the behavior of PCT with those of SAA and CRP. DESIGN: A prospective descriptive patient sample study and a controlled liver tissue culture study. SETTING: A university hospital. PATIENTS: Cancer patients who were treated with human tumor necrosis factor-alpha (rhTNF-alpha; 5 patients) or interleukin-6 (rhIL-6; 7 patients). MEASUREMENTS AND MAIN RESULTS: Serial serum samples were collected for analysis of concentrations of PCT, SAA, and CRP. In the TNF-alpha group, frequent sampling was performed on the first day to allow analysis of initial responses. In a human liver slice model, the release of PCT, SAA, and CRP was measured on induction with rhTNF-alpha and rhIL-6 for 24 hrs. We found that PCT displayed acute phase reactant behavior in vivo after administration of both rhTNF-alpha and rhIL-6. After rhTNF-alpha-administration, PCT reached half-maximal concentrations within 8 hrs, 12 hrs earlier than either SAA or CRP did. PCT, SAA, and CRP were produced in detectable quantities by liver tissue in vitro. PCT production by liver slices was enhanced after stimulation with rhTNF-alpha or rhIL-6; SAA and CRP concentrations were elevated after stimulation with rhTNF-alpha. CONCLUSIONS: We found that PCT and acute phase proteins such as CRP are induced by similar pathways. The liver appears to be a major source of PCT production. Thus, PCT may be considered an acute phase protein. The different kinetics of PCT, rather than a fundamentally different afferent pathway, may explain its putative diagnostic potential to discriminate bacterial infection from other causes of inflammation.

Bacterial Infections↗
PubMed1999

Albumin modified with mannose 6-phosphate: A potential carrier for selective delivery of antifibrotic drugs to rat and human hepatic stellate cells.

The hallmark of liver fibrosis is an increased extracellular matrix deposition, caused by an activation of hepatic stellate cells (HSC). Therefore, this cell type is an important target for pharmacotherapeutic intervention. Antifibrotic drugs are not efficiently taken up by HSC or may produce unwanted side-effects outside the liver. Cell-specific delivery can provide a solution to these problems, but a specific drug carrier for HSC has not been described until now. The mannose 6-phosphate/insulin-like growth factor II (M6P/IGF-II) receptor, which is expressed in particular upon HSC during fibrosis, may serve as a target-receptor for a potential carrier. The aim of the present study was to examine if human serum albumin (HSA) modified with mannose 6-phosphate (M6P) is taken up by HSC in fibrotic livers. A series of M6Px-modified albumins were synthetized: x = 2, 4, 10, and 28. Organ distribution studies were performed to determine total liver uptake. The hepatic uptake of M6Px-HSA increased with increasing M6P density. M6Px-HSA with a low degree of sugar loading (x = 2-10) remained in the plasma and accumulated for 9% +/- 0.5% or less in fibrotic rat livers. An increase in the molar ratio of M6P:HSA to 28:1 caused an increased liver accumulation to 59% +/- 9% of the administered dose. Furthermore, we determined quantitatively the in vivo intrahepatic distribution of M6Px-HSA using double-immunostaining techniques. An increased substitution of M6P was associated with an increased accumulation in HSC; 70% +/- 11% of the intrahepatic staining for M6P28-HSA was found in HSC. We also demonstrate that M6P-modified bovine serum albumin (BSA) accumulates in slices of normal and cirrhotic human livers. After incubation of this neoglycoprotein with human tissue, the protein is found in nonparenchymal liver cells. Because M6P-modified albumins are taken up by HSC in fibrotic livers, this neoglycoprotein can be applied as a selective drug carrier for HSC. This technology may create new opportunities for the pharmacological intervention of liver fibrosis.

Animals↗
PubMed1998

Effect of cold and warm ischaemia on drug metabolism in isolated hepatocytes and slices from human and monkey liver.

1. The influence of short-term cold storage in University of Wisconsin organ preservation solution (UW) on the ability to metabolize lidocaine, testosterone and 7-ethoxycoumarin in isolated human and cynomolgus monkey (Macaca fascicularis) hepatocytes and liver slices has been investigated. 2. The human liver tissue was obtained from two different sources, i.e. healthy liver tissue from patients undergoing partial hepatectomy because of metastases of colorectal carcinoma (PH livers) and donor tissue remaining as surgical waste after reduced size or split liver transplantation (Tx livers). Tx livers were perfused in situ with ice-cold UW avoiding warm ischaemia. This in contrast with PH livers, where the operation caused warm ischaemia for 5-90 min. 3. Liver slices and hepatocytes from cynomolgus monkey liver showed comparable metabolic rates for the substrates tested, indicating that all hepatocytes in the slice are participating in the biotransformation of the substrates. These monkey liver preparations can be stored up to 18 h with only a slight loss of their metabolic capacity. 4. Liver slices and isolated hepatocytes from the Tx livers as well as isolated cells from the PH livers could also be stored up to 18 h without losing metabolic capacity. However, for liver slices prepared from PH livers cold storage is not recommended, because metabolic function was reduced by approximately 40% after 18 h.

Animals↗
PubMed1998

A rapid and simple method for cryopreservation of human liver slices.

1. Precision-cut liver slices represent a suitable and convenient in vitro preparation for studying metabolism and toxicity mechanisms of drugs and toxic chemicals. Particularly in the case of human liver slices, cryopreservation would enable more efficient utilization of this scarce and irregularly available tissue. 2. Liver slices from consecutive human livers were cryopreserved using a method previously developed for rat and monkey liver slices. This procedure involves incubation in 12% dimethyl sulphoxide for 30 min on ice and direct immersion into liquid nitrogen. 3. Functional integrity of cryopreserved human liver slices, as compared with that of fresh liver slices, was maintained at 66 +/- 8% (alanine aminotransferase activity retained in the slices), 78 +/- 7% (urea synthesis), 88 +/- 14% (testosterone hydroxylation), 84 +/- 7% (N-deethylation of lidocaine) and 88 +/- 10% (total O-deethylation of 7-ethoxycoumarin). The ratios of testosterone metabolites did not change on cryopreservation. 4. These results show that the cryopreserved human liver slices retained the measured drug metabolism activities. Therefore, this cryopreservation method is suitable for storing liver slices to be used for comparing drug metabolism patterns, at least qualitatively, between species.

Animals↗
PubMed1998

Effect of human liver source on the functionality of isolated hepatocytes and liver slices.

In vitro experiments using human liver tissue to study drug metabolism and transport are usually performed and interpreted without real consideration of the differences in procurement of the tissue, if it is obtained from different sources. Therefore, in this study the functionality of isolated hepatocytes and liver slices prepared either from healthy human liver tissue obtained from patients undergoing partial hepatectomy [livers from partial hepatectomy (PH-livers)] or from donor tissue remaining after reduced-size or split-liver transplantation [livers from transplantation (Tx-livers)] was compared. From each liver sample, both liver slices and hepatocytes were prepared and compared with respect to viability and drug disposition. The viability of hepatocytes was assessed by trypan blue exclusion, ATP content, and energy charge and that of liver slices by potassium retention. In both preparations phase I metabolism was studied using lidocaine and testosterone as substrates, whereas phase I and II metabolism was assessed with 7-ethoxycoumarin. The membrane transport capability of the hepatocytes was investigated by measuring the uptake of taurocholic acid. The hepatocytes from PH-livers and Tx-livers showed similar viabilities and functional capacities. Metabolism in cells and slices from Tx-livers was found to be quantitatively comparable. However, liver slices from PH-livers showed a significantly lower metabolic capacity, compared with cells from the same tissue. This may indicate that only some of the hepatocytes in the liver slices from PH-livers participate in the metabolism of the compounds studied and that a selection of healthy cells takes place during isolation of the hepatocytes. Our results imply that hepatocytes isolated from Tx-livers and PH-livers can be used in the same study without consideration of the procurement of the tissue. However, the procurement of the tissue may significantly influence the functions of liver slices; the liver slices prepared from PH-livers showed significantly lower metabolic function, compared with slices prepared from Tx-livers.

Adenosine Triphosphate↗
PubMed1998

Characterization of the uptake of rocuronium and digoxin in human hepatocytes: carrier specificity and comparison with in vivo data.

Mechanisms of drug transport in the liver have been investigated predominantly in rodents. Most of the in vitro drug research in the liver is performed in liver preparations of animals. The results of such experiments frequently are discussed in relation to anticipated metabolic profiles in man, but these extrapolations are often inappropriate because of large interspecies differences in drug metabolism. In the present study, the mechanisms and specificity of the uptake of the organic cation rocuronium and the cardiac glycoside digoxin were investigated in human hepatocytes and were compared with results obtained in rat hepatocytes. The extraction ratio for the intact liver was calculated from the measured uptake rates of the compounds in the human cells in vitro and compared with published in vivo data. The initial hepatic extraction ratio, calculated from the in vitro uptake data for digoxin and rocuronium, very well reflected the initial extraction ratio for distribution in the liver in vivo in man. Uptake of 100 microM rocuronium was inhibited by 40 microM K-strophantoside (80% inhibition), and although not significantly, by 160 microM procainamide ethobromide, whereas no inhibitory effect was found in the presence of 160 microM taurocholic acid. In a previous study in rat hepatocytes, marked inhibition of digoxin uptake by quinine and only minimal inhibition by the diastereomer quinidine was demonstrated, showing clear stereoselectivity in transport inhibition. Unexpectedly, the uptake of digoxin in human hepatocytes was not inhibited significantly by quinidine or quinine, which indicates clear species differences. This is the first study to investigate the uptake mechanisms of organic cations and cardiac glycosides in human hepatocytes in some detail. The results show that uptake characteristics of drugs found in rats can not be extrapolated directly to humans.

Androstanols↗