Comparative effects of englitazone and glyburide on gluconeogenesis and glycolysis in the isolated perfused rat liver

Englitazone (CP 68,722, Pfizer) is a member of a family of drugs known as thiazolidinediones. One member of this family, troglitazone (Rezulin), is currently utilized in the treatment of Type 2 diabetes. Previous studies have focused on the ability of englitazone to increase insulin sensitivity in various tissues. However, little information is available regarding the direct effect of englitazone on hepatic glucose metabolism in the absence of insulin. Therefore, the following studies were conducted to comparatively evaluate the effect of englitazone and glyburide (a representative sulfonylurea) on gluconeogenesis and glycolysis from various substrates in the isolated perfused rat liver (IPRL). In isolated perfused rat livers of 24-hr fasted rats infused with lactate (2 mM), englitazone (6.25 to 50 microM) produced a concentration-dependent decrease (32-93%) in hepatic gluconeogenesis. When dihydroxyacetone (1 mM) and fructose (1 mM) were used as metabolic substrates, englitazone inhibited gluconeogenesis by 31 and 15%, respectively, while increasing glycolysis by 42 and 50%. Similar effects on gluconeogenesis and glycolysis were observed with glyburide, even though the effects with glyburide were more acutely evident, reversible, and of a greater magnitude. Such data suggest alterations in hepatic glucose production may contribute to the decrease in plasma glucose concentrations observed in individuals treated with englitazone and glyburide. These alterations may include effects on several regulatory enzymes (e.g. fructose-1,6-bisphosphatase, pyruvate kinase, and phosphoenolpyruvate carboxykinase), which warrant further investigation.     

Hepatobiliary transport of diflunisal conjugates and taurocholate by the perfused rat liver: the effect of chronic exposure of rats to diflunisal

Acyl glucuronides are reactive electrophilic metabolites of carboxylate drugs which can form covalent adducts with endogenous macromolecules such as serum albumin and hepatic proteins. Such adducts have been suggested as initiating factors in certain immune and toxic responses to acidic drugs. In the present study, pretreatment of rats with high daily doses (50 mg/kg orally) of the non-steroidal anti-inflammatory drug (NSAID) diflunisal (DF) for 35 days, followed by perfusion of the isolated liver with 3 mg DF for 3 hr, resulted in appreciable concentrations of covalent adducts of DF with hepatic tissue (3.68 microg DF/g liver). Immunoblotting using a rabbit polyclonal DF antiserum showed the major DF-modified bands at about 110, 140 and 200 kDa. A vehicle-pretreated control group achieved adduct concentrations of only 0.37 microg DF/g liver, with the 200 kDa band not detectable in immunoblots. Elimination of DF from perfusate of the isolated perfused rat liver (IPRL) preparation was the same (t1/2 about 3.4 hr) in both DF- and vehicle-pretreated groups. Appearance of the sulfate (DS) conjugate, the major metabolite in perfusate, was also similar. However, higher concentrations of the acyl glucuronide (DAG) and phenolic glucuronide (DPG) conjugates were found in perfusate at later times, though a statistically significant difference in area under the concentration-time curve was found only in the case of DAG. At 3 hr, recoveries of dose as DAG and DPG were significantly higher in perfusate, but not in bile. No significant differences in uptake and biliary excretion of taurocholate were found between the two groups. The finding of higher perfusate concentrations of DAG and DPG could signal a minor compromise to biliary excretion processes for the glucuronides, though whether such a result is simply coincident with or attributable to DAG-derived covalent DF-protein adducts in liver remains indeterminate.     

Intracellular redox state and control of gluconeogenesis in perfused chicken liver

The role of the cellular redox state in the control of gluconeogenesis was studied in hemoglobin-free perfused chicken liver, by fluorimetric measurement of the redox states of intracellular pyridine nucleotides. The aminotransferase inhibitor, aminooxyacetate, completely inhibited gluconeogenesis from lactate in the perfused rat liver and to a small extent in the perfused chicken liver. In chicken liver, the highest rate of glucose production was seen with lactate, followed by fructose, pyruvate, and glycerol. When compared at 5 mM, the rate of glucose production from pyruvate was only 10% of that from lactate. Glucose production from a pyruvate/lactate mixture decreased with increasing proportions of pyruvate, together with redox changes of pyridine nucleotides to a more oxidized state. Increased reduction of pyridine nucleotides upon infusion of ethanol was associated with an increased glucose production from pyruvate, and the increase was abolished during octanoate infusion. This abolishment was accompanied by an increase in the acetoacetate to beta-hydroxybutyrate ratio with an oxidation of pyridine nucleotides. The octanoate-inhibited gluconeogenesis occurred at the higher lactate concentration (10 mM) with a transient oxidation of pyridine nucleotides. No significant inhibition was observed at 1 mM lactate, although an instant reduction of pyridine nucleotides was taking place. The rate of beta-hydroxybutyrate generation during octanoate infusion was 2.2 times higher at 1 mM than at 10 mM lactate. The inhibitory effect of octanoate on glyconeogenesis was completely relieved by the addition of NH4Cl. The results demonstrate that the regeneration of NADH in the cytosol is limited in chicken liver, and that gluconeogenesis is regulated, in part, by alteration in the redox states of mitochondria and cytosol.     

Effects of the nonsteroidal anti-inflammatory drug nimesulide on energy metabolism in livers from adjuvant-induced arthritic rats

The effects of nimesulide on energy metabolism and the hepatic metabolic alterations produced by adjuvant-induced arthritis were investigated in the perfused rat liver an in isolated liver mitochondria. Nimesulide, at therapeutic levels (20-50 microM), produced: (1) stimulation of oxygen consumption in the perfused rat liver and in isolated mitochondria, (2) inhibition of gluconeogenesis; (3) reduction of ADP/O ratio and the respiratory control ratio and stimulation of glycogenolysis in the livers from healthy rats, but not in livers from arthritic rats. These results indicate that nimesulide acts as a mitochondrial uncoupler. The main alterations produced by adjuvant-induced arthritis were: higher rates of oxygen consumption in both perfused livers and isolated mitochondria, with no decrease in the efficiency of mitochondrial energy transduction; (2) decreased gluconeogenesis and lack of glycogenolytic response to uncouplers, but not to alpha 1-agonists. These data allow to conclude that nimesulide-induced impairment of energy metabolism should worsen the hepatic disturbances that are already associated with the adjuvant disease.     

Stimulation of gluconeogenesis with 1,3-butanediol in the perfused rat liver

An intensified synthesis of glucose is observed in gluconeogenesis from endogenous precursor only for the first 30 min of perfusion. Pyruvate introduction into the medium raises phosphoenolpyruvate carboxykinase and fructose-1,6-diphosphatase activities in the liver and determines maintenance of the glucose formation high rate for 90 min of perfusion. 1,3-butanediol is found to have a stimulating effect on gluconeogenesis from pyruvate. Introduction of 1,3 bytanediol into perfusate decreases the redox state of free NAD-pairs, increases the content of phosphoenolpyruvate, malate. ATP and the phosphoenolpyruvate carboxykinase and fructose-1.6-diphosphatase activity in the perfused liver.     

Hepatic uptake and biliary excretion of d-tubocurarine and trimethyltubocurarine in the rat in vivo and in isolated perfused rat livers

The clearance from perfusion medium and the biliary excretion of d-tubocurarine (d-TC) and trimethyltubocurarine (tMeTC) was studied in isolated perfused rat livers. Despite the related structure, d-TC exhibited considerably higher lipophilicity and plasma protein binding than its trimethyl derivative. Significant differences in hepatic disposition of the two agents were found. The clearance constant of elimination from the perfusate for d-TC was 2.00 and 0.41 ml/min for tMeTC. Fifty-one percent of the administered d-TC was excreted in the bile during 2 hours of perfusion. For tMeTC this amounted to only 16%. Bile/plasma concentration ratios of d-TC were 10 times those of tMeTC. There was no evidence for biotransformation of the substances. The unequal biliary output cannot be explained by differences in subcellular distribution. After injection into rats in vivo, the major part of drug in the liver is confined to the particulate fractions. Subfractionation studies indicate binding to lysosomes. The hepatocyte cytosol concentrations of d-TC and tMeTC are in the same order and are lower than the concomitant plasma concentrations. Both bile/liver and liver/plasms concentration ratios were higher for d-TC. The results support the idea that the balance of hydrophilic and hydrophobic properties is an important factor determining hepatic transport of organic compounds.     

A fish oil diet minimizes hepatic reperfusion injury in the low-flow, reflow liver perfusion model

In this study, the effects of fish oil treatment on hepatic reperfusion injury in a low-flow, reflow perfusion model were investigated. Rats were fed powdered diets containing either 5% corn or 5% encapsulated fish oil for 13 to 15 days. Average daily food intake in both control and fish oil groups was about 20 g per rat, and weight gain averaged 9 g/rat/d. Livers were perfused at flow rates around 1 muL/g/min for 75 minutes, which caused cells in pericentral regions to become anoxic because of insufficient delivery of oxygen. When normal flow rates (about 4 mL/g/min) were restored for 40 minutes, reperfusion injury occurred. Upon reflow, lactate dehydrogenase (LDH) release increased from basal levels around 1 to 50 IU/g/h in livers from control rats, whereas fish oil treatment minimized values to 16 IU/g/h Rates of bile production reached 23 muL/g/h during reperfusion in livers from controls and 38 muL/g/h in the fish oil-treated group. Oxygen uptake was about 110 mumol/g/h during the reperfusion period in livers from both groups. Malondialdehyde (MDA), an end product of lipid peroxidation, was released into the effluent perfusate at rates around 80 nmol/g/h during reperfusion in controls, and values were not affected by fish oil treatment, Portal pressure, an indicator of hepatic microcirculation, increased from basal levels of 3 to 10.5 cm H2O during reperfusion in controls, but was only elevated to 8.3 cm H2O in the fish oil-treated group. In addition, Trypan Blue distribution time, another indicator of hepatic microcirculation, was reduced significantly by 44% by fish oil treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Competition between sodium reabsorption and gluconeogenesis in kidneys of steroid-treated rats

Kidneys of rats treated with methylprednisolone show altered substrate requirements for sodium reabsorption when perfused in vitro. Such kidneys synthesize glucose from lactate at twice the rate of control. Optimum sodium reabsorption is not seen with glucose, which is normally the preferred substrate. Sodium reabsorption is restored toward normal by the combination of glucose and butyrate, by pyruvate, or by 3-mercaptopicolinate. All of these results point to a metabolic adaptation in the kidney; butyrate may improve sodium reabsorption by sparing glucose, pyruvate is a gluconeogenic precursor and an effective fuel of respiration, and 3-mercaptopicolinate is an inhibitor of gluconeogenesis. In kidneys from rats treated with methylprednisolone there is an increased requirement for metabolic energy because of the increased rate of gluconeogenesis. It is suggested that the availability of energy from glucose oxidation is limited in part by the diversion of pyruvate back to glucose. Under these special circumstances, gluconeogenesis competes with sodium reabsorption in the intact kidney.     

Role of glutathione in hepatic bile formation during reperfusion after cold ischemia of the rat liver

BACKGROUND/AIMS: Liver reperfusion following cold ischemia is frequently associated with diminished bile flow in patients undergoing liver transplantation. Glutathione is a major determinant of bile-acid independent bile flow, and the effects of cold ischemia on biliary glutathione excretion are unknown. METHODS: We examined the effects of cold ischemia (University of Wisconsin solution (4 degrees C), 24 h) with subsequent reperfusion (100 min) on biliary glutathione excretion in a recirculating system. Since glutathione might represent an important antioxidant within the biliary tract and oxidative stress in the biliary tract during reperfusion could contribute to the pathogenesis of bile duct injury after liver transplantation, we also assessed bile duct morphology in reperfused livers of mutant TR- -rats, in whom biliary excretion of glutathione is already impaired. RESULTS: Hepatic bile formation was diminished in reperfused Wistar rat livers after cold ischemia. Biliary glutathione concentrations and output were significantly decreased and correlated with postischemic changes in bile secretion. An increased biliary oxidized glutathione/glutathione ratio, indicating oxidative stress, was detected only immediately after the onset of reperfusion. Basal bile flow rates in TR- -rat livers which were already markedly reduced in control-perfused livers, decreased further during the early but not the later reperfusion period. Reperfusion of both Wistar and TR- -rat livers was not associated with electron microscopic evidence of bile duct damage. CONCLUSIONS: We conclude that impaired biliary excretion of glutathione contributes to decreased bile flow after cold ischemia. The absence of biliary glutathione does not appear to promote ultrastructural evidence of bile duct injury during reperfusion in the isolated perfused rat liver.     

Effect of an experimental malaria infection on the metabolism of phenacetin in the rat isolated perfused liver

1. The effect of infection with the rodent malaria parasite Plasmodium berghei on the metabolism of phenacetin has been investigated in a rat isolated perfused liver preparation. 2. A bolus dose of phenacetin (10 mg) was introduced into the perfusate reservoir of both control (n = 4) and malaria-infected (n = 4) liver preparations, and samples of bile and perfusate were collected (0-4 h) for hplc analysis of phenacetin, paracetamol and its phase II metabolites. 3. Whereas malaria had no effect on the hepatic clearance of phenacetin (control: 0.64 +/- 0.15 versus malaria: 0.66 +/- 0.14 ml min-1), there was a significant reduction in the hepatic clearance of generated paracetamol (control: 1.22 +/- 0.15 versus malaria: 0.41 +/- 0.08 ml min-1) and the total recovery in bile and perfusate of paracetamol glucuronide (control: 1.18 +/- 0.44 versus malaria: 0.29 +/- 0.20 mg). There was no significant change during malaria infection in the total recovery of either phenacetin (control: 1.30 +/- 0.73 versus malaria: 0.79 +/- 0.36 mg) or paracetamol sulphate (control: 0.81 +/- 0.25 versus malaria: 0.74 +/- 0.16 mg),     

Acute ethanol hepatotoxicity is modulated by bile salt hydrophilic-hydrophobic properties

The influence of the hydrophobic-hydrophilic properties of bile salts (BS) on acute ethanol hepatotoxicity was investigated. Bile flow, biliary BS secretion and enzyme (LDH,AST) release in the perfusate were measured before and after exposure to low (0.1%) or high (1%) doses of ethanol in in vitro isolated livers perfused with 1 microM/min taurocholate (TCA), tauroursodeoxycholate (TUDCA) or taurodeoxycholate (TDCA). Ethanol promotes a rapid decrease of basal bile flow and BS secretion in TCA-perfused livers [-28% of basal values with 0.1% (N = 6), and -35% with 1% ethanol (N = 6)]. Bile flow and BS secretion were minimally decreased by ethanol in livers perfused with a hydrophilic BS (TUDCA) [-8% decrease of basal values with 0.1% ethanol (N = 6), and -10% with 1% ethanol (N = 9); p < 0.02 vs TCA-perfused livers]. In contrast, when livers were perfused with a hydrophobic BS (TDCA), ethanol showed a higher cholestatic effect than either TCA- or TUDCA-perfused livers. Enzyme release in the perfusate was not modified by 0.1% ethanol, while 1% ethanol promoted a 4-5 fold increase in LDH and AST release in the perfusate of TCA-perfused livers with respect to a mere 2-fold increase in TUDCA-perfused livers and a 6-7 fold increase in TDCA perfused livers (p < 0.03). In conclusion, we showed that TUDCA almost completely counteracts the cholestatic and cytolitic effects promoted by ethanol in the isolated perfused rat liver.     

Hormone-induced bile flow and hepatobiliary calcium fluxes are attenuated in the perfused liver of rats made cholestatic with ethynylestradiol in vivo and with phalloidin in vitro

The actions of vasopressin and glucagon, administered alone or together, were assessed on bile flow in perfused livers from rats made cholestatic by the injection of ethynylestradiol and from those allowed to recover from such treatment. Concomitant measurements were made of biliary calcium output as well as changes in the perfusate Ca2+ concentration, glucose output, and oxygen uptake. Experiments were also conducted where cholestasis was induced in vitro in the perfused liver by the infusion of phalloidin. In each case cholestasis was demonstrated to have occurred by a reduction in bile flow by approximately 50%. The data show that the transient increase in bile flow and bile calcium seen in control rat liver soon after the administration of vasopressin, particularly when coadministered with glucagon, is largely absent in cholestasis induced by ethynylestradiol and attenuated in cholestasis induced by phalloidin. At the same time the pattern of perfusate Ca2+ fluxes in ethynylestradiol-induced cholestasis shifts to one reflecting net efflux of the ion from the liver. The responses to glucagon administration alone contrast with those of vasopressin in that in the perfused liver of ethynylestradiol-treated rats, glucagon induces a pronounced and sustained increase in bile flow. In cholestasis induced by both ethynylestradiol and phalloidin, glucagon fails to induce an initial transient decrease in bile flow. The effects of glucagon, including enhancement of vasopressin-stimulated bile flow in control and in ethynylestradiol-treated rats, can be mimicked by dibutyryl cyclic adenosine monophosphate (cAMP). Changes in glucose output and oxygen uptake induced by both hormones are only slightly attenuated. The data show that the modulation of bile flow that occurs rapidly after the administration of vasopressin and glucagon to control perfused rat liver is altered in conditions of cholestasis induced by either ethynylestradiol or phalloidin.     

The continuous kinetic determination of p-nitroanisole O-demethylation in hemoglobin-free perfused rat liver

P-Nitroanisole O-demethylation by perfused rat liver based on the spectral properties of the product, p-nitrophenolate, was determined continuously. Rates of p-nitrophenol production in this system were sensitive to inhibition by CO. p-Nitrophenolate production by livers of normal animals was linear for up to 30 minutes; however, rates were only linear for 1 to 2 minutes followed by a steady decline in induced (6-fold) livers from phenobarbital-treated rats. Only a small portion (24%) of this steady decline could be accounted for by the formation of conjugation products. Additionally, infusion of p-nitrophenol (14 micronM) was not associated with a decline in rate. The decline in rate in induced livers was reversed by glucose, suggesting that an intimate relationship may exist between drug and carbohydrate metabolism in the intact liver. Alteration in rates of p-nitroanisole metabolism with various inducing agents of the mixed-function oxidation system (phenobarbital; ethanol) produced parallel changes in rates of hepatic lactate production, most likely reflecting the aciton of p-nitrophenol to uncouple oxidative phosphorylation. The data support the hypothesis that the decline in rate in p-nitroanisole O-demethylation in livers from phenobarbital-treated rats is due to reduced availability of NADPH for mixed-function oxidation.     

Sinusoidal endothelial cell damage by activated macrophages in rat liver necrosis

BACKGROUND: Massive hepatic necrosis caused by fibrin deposition in the hepatic sinusoids develops with hepatic macrophage activation in rats given endotoxin after administration of heat-killed Corynebacterium parvum. Targeted cells of such macrophages were investigated. METHODS: In C. parvum-treated rats, the pathological appearance of liver cells was serially measured in serum following endotoxin administration and compared with the appearance in the perfusate during closed liver perfusion with endotoxin. RESULTS: Serum activities of tumor necrosis factor, purine nucleoside phosphorylase present in both hepatocytes and sinusoidal endothelial cells, and levels of alanine aminotransferase were higher after 30 minutes, 1 hour, and 3 hours, respectively. Pretreatment of rats with gadolinium chloride, an inhibitor of macrophage function, reduced this liver injury. Although alanine aminotransferase activity remained almost unchanged in the liver perfusate, purine nucleoside phosphorylase activity increased. This increase was reduced when rats were pretreated with gadolinium chloride. There was sinusoidal endothelial cell damage around hepatic macrophages in the liver perfused with endotoxin. CONCLUSIONS: Activated hepatic macrophages may cause sinusoidal endothelial cell damage leading to hepatocyte necrosis in rats given C. parvum and endotoxin.     

Moment analysis of stereoselective biliary excretion and chiral inversion of ketoprofen enantiomers in perfused rat liver

The stereoselective local disposition of ketoprofen was evaluated by the single-pass perfusion experiment following a bolus injection of R(-)- or S(+)-ketoprofen into the liver from the portal vein. The elution time profiles of enantiomers into the hepatic vein and the excretion time profiles into the bile were kinetically assessed by local moment analysis. The hepatic recovery ratios (FH) of both enantiomers were < 1%, and the mean hepatic transit times (tH) were approximately 7 s. After the injection of S-ketoprofen into the liver, the biliary excretion ratio (Fb) of total S-ketoprofen was 68% (15% S-ketoprofen and 53% glucuronide) and the mean biliary transit time (tb) of S-ketoprofen was 10 min. R-Ketoprofen inversion from S-ketoprofen was not observed in either the perfusate or in the bile. After the injection of R-ketoprofen, the Fb of total R-ketoprofen was 12% (3% R-ketoprofen and 9% glucuronide), and tb of R-ketoprofen was 8 min. The Fb of total S-ketoprofen inverted from R-ketoprofen was 24% (7% S-ketoprofen and 17% glucuronide), and the tb of inverted S-ketoprofen was 17 min. Forty-six percent of R-ketoprofen was inverted to S-ketoprofen during a single pass through the rat liver, and the mean inversion time was 7.5 min. It was concluded that the unidirectional chiral inversion of ketoprofen was stereospecific, and the hepatic uptake and biliary excretion were stereo-nonspecific.     

Vasopressin reduces taurochenodeoxycholate-induced hepatotoxicity by lowering the hepatocyte taurochenodeoxycholate content

BACKGROUND/AIMS: Vasopressin has been reported to reduce bile flow, but its effects on bile acid secretion and bile acid-related hepatotoxicity are still unclear. We therefore investigated the influence of vasopressin on the hepatotoxicity and biliary excretion of taurochenodeoxycholic acid in primary cultured rat hepatocytes and isolated perfused rat liver models. METHODS/RESULTS: 1) Addition of vasopressin to hepatocyte cultures significantly decreased lactate dehydrogenase release as compared to cultures exposed to 1 mM taurochenodeoxycholic acid alone, and also reduced intracellular taurochenodeoxycholic acid content from 19.3 +/- 2.2 to 13.0 +/- 1.6 nmol/mg protein. After 30 min of preincubation with 1 mM taurochenodeoxycholic acid, rinsing and reculture of hepatocytes in bile acid-free medium resulted in gradual decrease in the intracellular level of the bile acid, and addition of vasopressin (10(-9) M) to the reculture medium accelerated this process. 2) Superimposition of vasopressin (330 pmol/l) for 10 min on taurochenodeoxycholic acid infusion (1.0 mumol/min: 25 mumol/l) caused a rapid increase in bile flow and biliary excretion of taurochenodeoxycholic acid (697 +/- 42 vs 584 +/- 27 nmol/10 min per g liver) from perfused rat livers, and significantly reduced lactate dehydrogenase release. 3) Superimposition of the PKC blocker H-7 (5 mumol/l) on taurochenodeoxycholic acid infusion (1.0 mumol/min: 25 mumol/l) caused a gradual increase in bile flow and biliary excretion of taurochenodeoxycholic acid. Furthermore, an additional infusion of vasopressin (100 pmol/l) for 10 min in the presence of H-7 produced a greater increase in bile flow and biliary excretion of taurochenodeoxycholic acid as compared with H-7 alone (754 +/- 71 vs. 657 +/- 26 nmol/g liver). 4) Continuous infusion of vasopressin (330 pmol/l) significantly increased the late peak (10-50 min) of horseradish peroxidase excretion from perfused livers (from 8.48 +/- 1.02 to 21.7 +/- 6.02 ng/g liver). CONCLUSIONS: These findings suggest that vasopressin exerts a protective effect against taurochenodeoxycholic acid-induced hepatotoxicity by stimulating the secretion of this bile acid via intracellular vesicular transport systems.     

Histochemical observation of the effect of electroacupuncture on the livers of rats with endotoxic shock

The experimental rats were randomly divided into three groups: i.e. control group; endotoxic shock group (the model of endotoxic shock was induced by intravenous administration of E. Coli endotoxin, 16 mg/kg); and electroacupuncture (EA) group ("Renzhong" or "Zusanli" acupoint was stimulated for 15 minutes at 1 hr after injection of endotoxin). The experimental rats were decapitated at 75 minutes after injecting endotoxin. Their livers were taken out for cryostat section, and histochemical observation. The results were as follows: 1) The glycogen in the hepatic cells of endotoxic shocked rats were almost completely depleted. The activities of SDH Mg(++)-ATPase and G-6-Pase and 5'-Nase were decreased; especially the activities of 5'-Nase in the biliary canaliculi and sinusoids were apparently reduced. 2) The content of hepatic glycogen in EA group was increased, but some of them was still depleted. The activities of SDH, Mg(++)-ATPase and G-6-Pase were slightly increased as compared with that of the endotoxic shock group. The activity of 5'-Nase was obviously increased after EA. The preliminary results indicated that EA at "Renzhong" or "Zusanli" acupoint of rats with endotoxic shock might play certain role on improving the hepatic metabolism and promoting the membrane transport action.     

Neutrophils prevent extracellular colonization of the liver microvasculature by Salmonella typhimurium

The early course of hepatic infection with the facultative intracellular bacterial pathogen Salmonella typhimurium was examined in control mice and in mice selectively depleted of neutrophils by treatment with a granulocyte-specific monoclonal antibody. The results show that >200-fold more salmonellae were recovered in livers of the latter group of mice than in livers of the former group by 24 h of parenterally initiated infection. Comparative histological examination of the livers from both groups of mice indicated that neutrophils participate in early anti-Salmonella defense in the liver in part by aborting infection in permissive hepatocytes and by inhibiting extracellular bacterial colonization of the hepatic microvasculature. It is shown in addition that systemic salmonellosis was also severely exacerbated in neutropenic mice infected intragastrically with the pathogen.     

Generation of coagulation factors V, XI, and XII by the isolated rat liver

When isolated rat livers were perfused with platelet-free erythrocytes suspended in Tyrode's solution containing 6% bovine serum albumin, the generation of factors V, XI, and XII was clearly demonstrable. On average, after 5 h of perfusion of a single liver, the concentrations in the perfusate (as a percentage of normal rat plasma) were about 6% for factor V, 8% for factor XI, and 5% for factor XII, compared with 20% for factor VII, which was used as the reference standard. When two livers were perfused, approximately twice these concentrations were achieved. When the properties of these factors in perfusate and plasma were compared, they agreed well except for differences in the celite adsorbability of factors XI and XII.     

The regulation of 3-hydroxy-3-methylglutaryl coenzyme A reductase in the isolated perfused rat liver

The effect of perfusion of an isolated rat liver on hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase was studied. In liver removed during the basal period of the diurnal cycle of enzyme activity, a 227 +/- 41% increase in enzyme activity occurred after 3 h of a plasma-free perfusion. This could be prevented by the addition of cycloheximide or pure cholesterol (dispersed with lecithin) to the perfusate. In contrast, the continuous addition of taurocholate or taurochenodeoxycholate, alone or in combination, at a variety of rates did not prevent the increase in enzyme activity. The added bile salts were efficiently extracted from the perfusate and excreted in the bile. The addition of these bile salts to a cholesterol-enriched perfusate did not alter the effect obtained with cholesterol alone. If the perfusate contained whole serum, the increase induced by perfusion in the basal period was smaller (88 +/- 27%) than with plasma-free perfusate. Again, the major bile salts of the rat failed to prevent the increase in enzyme activity induced by liver perfusion. If livers were removed and perfused at the height of the diurnal cycle of enzyme activity, the enzyme activity remained high (2 +/- 10% increase) rather than decreasing, as occurs in vivo. If cholesterol was added to these perfusions, a 52 +/- 4% decrease was induced. Bile salt addition induced no decrease. From the results it is concluded that the major bile salts are not direct regulators of hepatic cholesterol synthesis, but pure cholesterol, in the absence of bile salt or lipoprotein, is able to initiate the mechanism that represses hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase.