GSH attenuates organ injury and improves function after transplantation of fatty livers.

Ischemia-reperfusion injury (IRI) is increased after transplantation of steatotic livers. Since those livers are increasingly used for transplantation, protective strategies must be developed. Reactive oxygen species (ROS) play a key role in hepatic IRI. In lean organs, glutathione (GSH) is an efficient scavenger of ROS, diminishing IRI. The aim of this study was to evaluate whether GSH also protects steatotic allografts from IRI following transplantation. Fatty or lean livers were explanted from 10-week-old obese or lean Zucker rats and preserved (obese 4 h, lean 24 h) in hypothermic University of Wisconsin solution. Arterialized liver transplantation was then performed in lean syngeneic Zucker rats. Recipients of fatty livers were treated with GSH (200 µmol/h/kg) or saline during reperfusion (2 h, n = 5). Parameters of hepatocellular damage and bile flow were measured. Transplantation of steatotic livers enhanced early reperfusion injury compared to lean organs as measured by increased aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase plasma levels. Bile flow was also reduced in steatotic grafts. Intravenous administration of GSH effectively decreased liver damage in fatty allografts and resulted in improved bile flow. Intravenous application of GSH effectively reduces early IRI in steatotic allografts and improves recovery of these marginal donor organs following transplantation.

Microcirculatory failure after rat liver transplantation is related to Kupffer cell-derived oxidant stress but not involved in early graft dysfunction.

BACKGROUND: Microcirculatory failure, activation of Kupffer cells (KC), and the formation of reactive oxygen species (ROS) are considered pivotal mechanisms of reperfusion injury after orthotopic liver transplantation. However, the sequence of these events and their impact on early graft function remain controversial. We therefore investigated whether KC induce microcirculatory disturbances through ROS release and whether microcirculatory failure contributes to early graft function after liver transplantation. METHODS: Donor livers of Lewis rats were pretreated either with saline or with gadolinium chloride (GdCl3), an inhibitor of KC function (n=8 each). Syngeneic OLT was performed after 24 hr of hypothermic preservation in University of Wisconsin solution. RESULTS: Intravital microscopy revealed significantly higher sinusoidal perfusion rates in GdCl3-treated allografts (92+/-1.1% vs. 75.7+/-0.8%; P<0.001) compared with untreated controls; permanent leukocyte sticking in sinusoids (23.5+/-2.1 vs. 62.6+/-3.3 cells/lobule, P<0.001) and in postsinusoidal venules (153.1+/-10.4 vs. 446.6+/-46.4 cells/mm(2), P<0.001) were markedly attenuated in GdCl3-treated allografts. Improvement of microcirculatory parameters in GdCl3-treated livers was correlated with a significant reduction of plasma glutathione disulfide formation by KC-derived ROS (0.96+/-0.1 microM vs. 1.79+/-0.5 microM; P<0.01). Despite these beneficial effects, GdCl3-pretreatment failed to improve postischemic alanine aminotransferase release and bile flow. CONCLUSIONS: Microcirculatory failure after liver transplantation is related to KC-derived oxidant stress but not involved in early graft dysfunction.

Peptidoleukotrienes increase the efflux of glutathione from perfused rat liver.

The effect of peptidoleukotrienes (LT) on the efflux of glutathione (GSH) from the perfused rat liver was investigated. LTD4, C4 and E4 were infused at a final concentration of 20 nM into the portal vein of rat livers perfused with Krebs-Henseleit buffer. Perfusion pressure, efflux of glucose and release of LDH increased during the infusion of LTC4 and D4 and returned to baseline upon cessation of the infusion of LT. In contrast, the efflux of GSH did not change during the infusion of LT, but increased from 15 +/- 2 to 26 +/- 4 nmol/min.g liver 20 min after cessation of the infusion of LTC4. LTE4 did not increase the efflux of LDH, glucose, lactate, or GSH. During the LTC4- and LTD4-induced rise in perfusion pressure bile-flow decreased transiently by one third. The biliary excretion of GSH, however, decreased by an average of 75% and recovered more slowly than the cholestasis. In the presence of the selective LTD4 receptor antagonist LY171883 the effects of LTC4 and LTD4 were largely abolished. The delayed effects of LT on GSH efflux suggest that LT shift the efflux of GSH from the canalicular towards the sinusoidal side of the hepatocyte independent of other effects of LT on hepatic function. The sustained increase in efflux of GSH resulting from LT will raise the extracellular concentration of this antioxidant, such that more GSH is available at sites of inflammation to detoxify reactive oxygen species released by activated inflammatory cells.

Perforation of the colon: a rare complication of hepatocellular carcinoma.

Direct infiltration of the colon by hepatocellular carcinoma (HCC) is a rare condition. Only a few reports can be found in the literature. Here we present a case of direct infiltration of the ascending colon by an exophytic growing HCC of the right posterior liver lobe, in which treatment with transarterial chemoembolization (TACE) had been performed. Tumor invasion became evident by abdominal pain and lower gastrointestinal bleeding. Diagnosis was established by contrast-enhanced multidetector computed tomography (CE-MDCT), demonstrating the direct tumor invasion with concomitant perforation of the infiltrated colon segment. Based on these findings, rapid and effective surgical treatment could be achieved.

Effects of hypochlorous acid and chloramines on vascular resistance, cell integrity, and biliary glutathione disulfide in the perfused rat liver: modulation by glutathione.

The accumulation of polymorphonuclear leucocytes (PMN) may play an important role in liver injury by toxins and ischemia/reperfusion. Upon activation these cells generate hypochlorous acid (HOCl) and long-lived oxidants such as monochloramine (NH2Cl) and taurinechloramine (TauNHCl) which could contribute to organ injury when PMN accumulate in the liver. Therefore, the effects of HOCl, NH2Cl and TauNHCl on hepatic function were investigated in the perfused rat liver. HOCl at a concentration of 2.7 microM resulted in a marked increase in the perfusion pressure and the release of LDH associated with a decrease in bile flow. These effects were abolished by increasing the concentration of extracellular glutathione in the perfusate to physiological levels. NH2Cl (15 microM) and TauNHCl (65 microM) increased the perfusion pressure only slightly, but resulted in significant increases in the biliary excretion of glutathione disulfide, indicating that chloramines are reduced intracellularly by glutathione. The increment in biliary glutathione disulfide depended on the amount of chloramine taken up by the liver. The extraction of NH2Cl averaged 98% compared to 13% for TauNHCl. The present data indicates that intra- and extracellular glutathione plays an important role not only in the detoxification of O2-. and H2O2 generated by activated PMN but also in the protection against the cytotoxic effects of products of myeloperoxidase released by PMN upon activation.

Glutathione metabolism in activated human neutrophils: stimulation of glutathione synthesis and consumption of glutathione by reactive oxygen species.

Since glutathione (GSH) is involved in the modulation of the function of polymorphonuclear leucocytes (PMN) such as phagocytosis and production of reactive oxygen species, the metabolism of GSH was studied in human PMN. The concentration of GSH in resting PMN amounted to 13.3 nmol 10(-7) PMN and remained stable over 100 min of incubation. Upon activation of PMN with phorbol myristate acetate intracellular GSH decreased to 50% of the resting concentration within 80 min. In the presence of buthionine sulfoximine, which inhibits the synthesis of GSH, the depletion of intracellular GSH was dramatically accelerated, indicating that activation of PMN is associated with a marked stimulation of GSH synthesis. Since a similar depletion of GSH was seen in the presence of propargylglycine, an inhibitor of the cystathionine pathway, most of the cysteine required for the resynthesis of GSH must originate from methionine and not from cysteine generated by the catabolism of GSH. Further studies showed that GSH is sequentially oxidized by O2-. and HOCl, first to GSSG and then to an unidentified compound, most likely a chloramine. In the presence of an adequate supply of GSH and NADPH which is required for the reduction of GSSG by glutathione reductase this further oxidation of GSSG was prevented. Thus, the highly toxic HOCl generated by PMN can be detoxified by the glutathione reducatase system. The capacity of PMN to re-synthesize GSH may be an important determinant of PMN function.

Oxidant stress and potentiation of ischemia/reperfusion injury to the perfused rat liver by human polymorphonuclear leukocytes.

The accumulation and activation of polymorphonuclear leukocytes in the liver may play an important role in liver damage following ischemia and reperfusion. To study the effects of polymorphonuclear leukocytes on hepatic function, human polymorphonuclear leukocytes were infused into perfused rat livers. Infusion of polymorphonuclear leukocytes into continuously oxygenated livers led to an increased consumption of oxygen by the perfused liver which paralleled the production of superoxide anion radicals by activated polymorphonuclear leukocytes. The increased use of oxygen was followed by a decrease in the sinusoidal efflux of glutathione and a marked increase in the biliary excretion of glutathione disulfide, indicating that polymorphonuclear leukocytes were activated within the liver, and created a potentially deleterious oxidant stress. When polymorphonuclear leukocytes were infused into rat livers that had been subjected to 45 min of warm ischemia followed by reperfusion, the release of lactate dehydrogenase upon reperfusion of ischemic liver was significantly higher from livers exposed to polymorphonuclear leukocytes than from livers subjected to the same period of ischemia without leukocytes. This indicates that polymorphonuclear leukocytes potentiate ischemia/reperfusion injury. The present in vitro system provides a model to study pharmacological interventions designed to modulate the potentially deleterious interactions of polymorphonuclear leukocytes with the liver.

Relation between glutathione redox changes and biliary excretion of taurocholate in perfused rat liver.

The influence of the intracellular glutathione status on bile acid excretion was studied in the perfused rat liver. Perturbation of the thiol redox state by short term additions of diamide (100 microM) or hydrogen peroxide (250 microM) or t-butyl hydroperoxide (250 microM) led to a reversible inhibition of biliary taurocholate release without affecting hepatic uptake; inhibition amounted to 45% for diamide and 90% for the hydroperoxides. Concomitantly, the bile acid accumulated intracellularly. Bile flow increased from 1.3 to 2.0 microliters X min-1 X g liver-1 upon infusion of taurocholate (10 microM); the latter value was suppressed to 1.2 microliters X min-1 X g liver-1 by the addition of t-butyl hydroperoxide (250 microM). Similarly, the hepatic disposition of another bile constituent, bilirubin, was suppressed by 70% upon addition of hydrogen peroxide. While the addition of hydrogen peroxide inhibited also the endogenous release of bile acids almost completely, endogenous bile flow was much less affected, decreasing from 1.3 to 1.0 microliters X min-1 X g liver-1. Measurement of [14C]erythritol clearance showed bile/perfusate ratios of about unity both in the absence and presence of hydrogen peroxide, suggesting canalicular origin of the bile under both conditions. In livers from Se-deficient rats low in Se-GSH peroxidase (less than 5% of controls), hydrogen peroxide inhibited taurocholate transport substantially less, providing evidence for the involvement of glutathione in mediating the inhibition observed in normal livers. The percentage inhibition of taurocholate release and intracellular glutathione disulfide (GSSG) content were closely correlated. The addition of t-butyl hydroperoxide caused a several-fold increase of biliary GSSG release, whereas biliary GSH release was even decreased. The results establish a role of glutathione in canalicular taurocholate disposition.

Evaluation of serum cystatin C concentration as a marker of renal function in patients with cirrhosis of the liver.

BACKGROUND AND AIMS: Diagnosis of moderately impaired renal function is of particular importance in patients with cirrhosis of the liver. Whereas patients with a markedly impaired glomerular filtration rate can be diagnosed easily by elevated serum creatinine concentrations, moderately reduced renal function may be missed by this conventional parameter. Recently, cystatin C has been suggested as a sensitive marker of renal function, independent of sex or muscle mass. Therefore, the aim of this study was to investigate the value of serum cystatin C concentration for the detection of moderately impaired renal function. METHODS: Ninety seven in-hospital patients with cirrhosis and a 24 hour creatinine clearance of at least 40 ml/min were investigated and divided into group 1 (creatinine clearance > or = 70 ml/min; n = 55) and group 2 (creatinine clearance 40-69 ml/min; n = 42). RESULTS: Serum cystatin C concentrations (mean (SD): 1.31 (0.51) v 1.04 (0.34) mg/l (p = 0.008)) and creatinine concentrations (1.03 (0.52) v 0.86 (0.22) mg/100 ml (p=0.03)) were higher in group 2 than in group 1; there was no significant difference in urea concentrations. Receiver-operator characteristics (ROC) revealed a differential diagnostic advantage of cystatin C over creatinine and urea. At cut off concentrations of 1.0 mg/l, 0.9 mg/100 ml, and 28 mg/100 ml, respectively, cystatin C, creatinine, and urea exhibited 69%, 45%, and 44% sensitivity (p<0.05). As patients with a small muscle mass or reduced physical activity could be particularly prone to overestimation of their renal function, separate analyses were performed for the subgroups of female and Child-Pugh class C patients, respectively. In both groups, discrimination between patients with moderately impaired and normal renal function was best with cystatin C. In female patients, sensitivity of cystatin C (77.8%) was superior (p<0.05) to that of creatinine (38.9%) and urea (41.2%). In Child-Pugh C patients, the ROC curve was significantly better for cystatin C than for creatinine. CONCLUSIONS: Serum cystatin C determination could be a valuable tool in patients with cirrhosis, particularly with Child-Pugh class C or in female patients, for early diagnosis of moderately impaired renal function.

Prolonged antagonism of alpha 1-adrenergic vasoconstriction in the rat liver by atrial natriuretic peptide.

BACKGROUND/AIMS: Vasodilator hormones that regulate hepatic circulation at physiological concentrations have not been sufficiently identified. The presence of atrial natriuretic peptide (ANP) and its receptors in the hepatic vascular bed suggest such vasorelaxing potential. METHODS: Livers of male Sprague-Dawley rats were perfused in a flow-constant fashion. The selective alpha 1-adrenergic agonist phenylephrine (PE) (1.5 mumol/L) was infused from 30 to 36 minutes and again from 70 to 76 minutes after starting perfusion (n = 5). ANP (0.1 pmol/L to 200 nmol/L), des-(Gln18, Ser19, Gly20, Leu21, Gly22)-ANP fragment (C-ANP) (20 nmol/L), or 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) (50 mumol/L) (each n = 4) were added from 20 to 40 minutes. RESULTS: During the first infusion of PE, portal pressure increased from 3.7 +/- 0.5 to 12.1 +/- 0.8 cm H2O maximally (mean +/- SD) and increased again to 11.5 +/- 2.0 during the second PE infusion. ANP at physiological concentrations reduced both PE-induced increases of portal pressure in a dose-dependent fashion, reaching half-maximal effects around 20 pmol/L and maximal effects (about 50% inhibition of PE-induced vasoconstriction) at 40 pmol/L. The cGMP analogue 8-Br-cGMP showed the same long-lasting vasodilating effect as ANP. In contrast, C-ANP, which binds only to the ANP C-receptor, had no effects. CONCLUSIONS: Physiological concentrations of ANP antagonize alpha 1-adrenergic vasoconstriction in the liver, suggesting an important function in the humoral regulation of hepatic circulation. The prolonged hemodynamic effect of ANP seems to be ANP A-receptor/guanylyl cyclase/cGMP-mediated.

Prevention of ischemia/reperfusion injury in the rat liver by atrial natriuretic peptide.

BACKGROUND/AIMS: Atrial natriuretic peptide (ANP) protects against hypoxia/reoxygenation-induced damage of cultured hepatocytes, thus suggesting a therapeutic potential in the liver. Therefore, the effects of ANP on hepatic ischemia/reperfusion injury after warm ischemia were studied. METHODS: Livers of male Sprague-Dawley rats subjected to 60 minutes of warm ischemia at 37 degrees C were perfused in the presence or absence of 200 and 20 nmol/L ANP. RESULTS: Sinusoidal lactate dehydrogenase efflux increased to 2000 +/- 264 and 126 +/- 50 mU.min-1.g liver-1 after 1 minute and 60 minutes of reperfusion, but it only increased to 1240 +/- 160 and 22 +/- 16 mU.min-1.g liver-1 in the presence of 200 nmol/L ANP during the preischemic and postischemic perfusion period. The postischemic bile flow (0.67 +/- 0.18 microL.min-1.g liver-1) was significantly improved with 200 nmol/L ANP (0.92 +/- 0.05) and showed a linear correlation to biliary glutathione excretion. In contrast, 20 nmol/L ANP had no protective effects. Administration of 200 nmol/L ANP during the preischemic perfusion period alone (but not after starting reperfusion) markedly preserved postischemic liver function. CONCLUSIONS: Continuous ANP administration or ANP pretreatment alone prevents hepatic ischemia/reperfusion injury, possibly because of influences on intracellular signal transduction processes. The correlation between bile flow and biliary glutathione excretion supports the hypothesis that biliary glutathione transport is one of the osmotic driving forces in postischemic bile formation.

The relationship of biliary glutathione disulfide efflux and intracellular glutathione disulfide content in perfused rat liver.

The intracellular glutathione redox state was estimated using newly adapted methods for tissue analysis. Under standard perfusion conditions of rat liver perfused in situ, intracellular GSH content was 5.5 mumol X g of liver-1, and intracellular GSSG content was 18 nmol X g of liver-1, resulting in a GSH/GSSG ratio of 300. GSSG was transported from the cells into bile. The control rate of release amounts to 0.4 nmol X min-1 X g of liver-1 and corresponds to the rate of release previously observed in anesthetized animals (Sies, H., Koch, O., Martino, E., and Boveris, A. (1979) FEBS Lett. 103, 287-290). No GSSG was released into the caval perfusate. In contrast, GSH release occurs both into bile and into the sinusoidal space, the rates of release being 1 and 14 nmol X min-1 X g of liver-1, respectively. Biliary GSH release in very low in isolated perfused liver. The relationship between intracellular GSSG levels and the rate of biliary GSSG transport was studied. This was achieved in experiments in which internal hydrogen peroxide formation was stimulated with substrates for monoamine oxidase (pargyline-sensitive), or by addition of t-butyl hydroperoxide, or of nitrofurantoin. The apparent concentration ratio, GSSG in bile/GSSG intracellular, was about 50 over the range of intracellular GSSG examined.

Long-term therapy and retreatment of hepatorenal syndrome type 1 with ornipressin and dopamine.

Peripheral vasodilation is considered an important factor in the pathophysiology of the hepatorenal syndrome (HRS). Therefore, the aim of this study was to evaluate the therapeutic potential of the vasoconstrictor ornipressin plus dopamine in the treatment of the most severe form of HRS, namely HRS type 1. Seven cirrhotic patients (creatinine clearance 15 +/- 1 mL/min, UNaV 7 +/- 2 mmol/24 h) with HRS type 1 were included in the study after normalization of central venous pressure with intravenous albumin and low-dose dopamine had failed to prevent further deterioration of renal function. Ornipressin was given continuously (intravenous 6 IU/h) in combination with dopamine (2-3 microgram/kg/min) until creatinine clearance had increased to above 40 mL/min or adverse events prevented further treatment. HRS was reverted in 4 of 7 patients after 5 to 27 days (creatinine clearance 51 +/- 4 mL/min, UNaV 47 +/- 11 mmol/24 h) of treatment. Withdrawal was necessary in 1 patient after 15 days because of intestinal ischemia. Treatment failure was observed in 2 of 7 patients (creatinine clearance 19 +/- 10 mL/min, UNaV 8 +/- 3 mmol/24 h). Two of 4 responders had recidivant HRS 2 and 8 months after initial therapy, respectively. HRS in 1 of these patients was reverted with 18 days of ornipressin retreatment. The other patient had to be withdrawn from ornipressin after 2 hours because of ventricular tachyarrhythmia. Altogether, 3 of 7 patients survived HRS type 1, 1 after successful ornipressin therapy and liver transplantation, 1 with 2 successful courses of ornipressin, and 1 with liver transplantation after ornipressin treatment had failed. Thus, ornipressin plus dopamine can be a useful therapeutic option in patients with HRS type 1, especially as bridge to liver transplantation.

Glutathione protects the rat liver against reperfusion injury after hypothermic preservation.

BACKGROUND & AIMS: The extracellular generation of reactive oxygen species (ROS) by Kupffer cells contributes to reperfusion injury of the liver allograft. The endogenous antioxidant glutathione (GSH) can detoxify these ROS; however, this effect might be limited by the low extracellular concentration of GSH. We therefore investigated whether an increase of extracellular GSH protects the liver against reperfusion injury after cold preservation. METHODS: Livers of male Sprague-Dawley rats subjected to 24 hours of cold ischemia in University of Wisconsin solution (4 degrees C) were reperfused for 2 hours in the absence (controls) or presence of 0.5, 1, 2, or 4 mmol/L GSH (n = 4-6 each). RESULTS: Two hours after starting reperfusion of control livers, the sinusoidal release of lactate dehydrogenase and purine nucleoside phosphorylase increased to 247 +/- 96 and 27 +/- 13 mU. min(-1). g liver(-1), respectively, but only to 76 +/- 43 and 10 +/- 4 mU. min(-1). g liver(-1) in the presence of 4 mmol/L GSH. This cytoprotective effect was confirmed histologically by a marked reduction of trypan blue staining of hepatocytes. Compared with control livers, postischemic bile flow was significantly enhanced by GSH (0.15 +/- 0.02 vs. 0.41 +/- 0.11 microL. min(-1). g liver(-1)), indicating improved liver function. During reperfusion of control livers, intracellular GSH content declined from 4.5 +/- 0.3 to 2.3 +/- 0.1 micromol/g liver, but only to 3.8 +/- 0.4 micromol/g liver in the presence of 4 mmol/L GSH. Reperfusion of untreated livers was accompanied by a prolonged increase of portal pressure to maximally 12.5 +/- 1.9 cm H2O, which was significantly attenuated by 4 mmol/L GSH (7.2 +/- 1.4 cm H2O). Similar cytoprotective and hemodynamic effects were observed with 2 mmol/L GSH, but not with 0.5 and 1 mmol/L GSH. CONCLUSIONS: Treatment of cold-preserved livers with GSH upon reperfusion prevents damage of hepatocytes, deterioration of the hepatic circulation, and loss of intracellular GSH. In view of these protective effects and its low toxicity in humans, GSH should be considered a candidate drug for prevention of ROS-related reperfusion injury of the liver allograft.

Role of the liver in splanchnic extraction of atrial natriuretic factor in the rat.

Mesenteric, hepatic and splanchnic extraction of C-terminal and N-terminal atrial natriuretic factor was investigated in male Sprague-Dawley rats. Plasma concentrations (mean +/- S.E.M.) of C-terminal atrial natriuretic factor were 55.0 +/- 6.1 fmol/ml, 31.2 +/- 4.0 fmol/ml and 23.5 +/- 3.3 fmol/ml (n = 12) in the abdominal aorta, the portal vein and the hepatic vein, respectively. N-terminal atrial natriuretic factor plasma levels in these vessels were 3031 +/- 756 fmol/ml, 2264 +/- 661 fmol/ml and 1618 +/- 496 fmol/ml (n = 6), respectively. Although the mesenteric extraction ratio was higher (p less than 0.05) for C-terminal atrial natriuretic factor (42% +/- 6%) than for N-terminal atrial natriuretic factor (28% +/- 4%), there were no significant differences in the hepatic extraction ratio (41% +/- 5% vs. 39% +/- 6%) and the splanchnic extraction ratio (56% +/- 5% vs. 50% +/- 7%). These data suggest a major role of the liver in the splanchnic extraction of C-terminal and of N-terminal atrial natriuretic factor in the rat.

The guanylate cyclase-coupled natriuretic peptide receptor: a new target for prevention of cold ischemia-reperfusion damage of the rat liver.

The aim of our studies was to investigate hormonal prevention of hepatic preservation damage by the atrial natriuretic peptide (ANP) and the mechanisms involved. Isolated perfusion of rat livers was performed in a nonrecirculating fashion. Twenty minutes of preischemic perfusion was performed with or without different concentrations of ANP, followed by 24-hour storage in cold University of Wisconsin (UW) solution. Two hundred nanomoles of ANP prevented hepatocellular damage during a 2-hour reperfusion period as indicated by a marked attenuation of the sinusoidal efflux of lactate dehydrogenase (LDH) and purine nucleoside phosphorylase (PNP), and by reduced Trypan blue uptake. Furthermore, postischemic bile flow as an indicator of liver function was significantly improved by about 60% with 200 nmol/L ANP. No protection was conveyed by 20 nmol/L ANP nor by pretreatment with 200 nmol/L ANP for only 10 minutes. The effects of ANP seemed to be mediated by the guanylate cyclase-coupled A (GC-A) receptor and cyclic guanosine monophosphate (cGMP): whereas expression of both GC-A and GC-B receptors as well as of the GC-C receptor was found, cGMP did protect from ischemia-reperfusion damage, but selective ligands of the B and C receptor did not. To begin to determine the mechanisms of ANP-mediated protection, different parameters were investigated: ANP had no effect on portal pressure as an indicator of hepatic circulation, nor on intracellular energy depletion determined by adenosine nucleotide concentration. However, the marked augmentation of nuclear factor kappaB (NF-kappaB) binding activity during reperfusion was prevented in ANP-pretreated livers. In conclusion, pretreatment with ANP protects the rat liver from cold ischemia-reperfusion damage. This effect is mediated via the GC-A receptor and cGMP, and may be linked to an influence of ANP on NF-kappaB activation. Thus, ANP signaling via the GC-A receptor should be considered as a new pharmacological target to prevent preservation injury of the liver.

Ethanol decreases plasma sulphydryls in man: effect of disulfiram.

Based on animal experiments, interactions of ethanol and its metabolites with sulphydryls have been implicated in the toxicity of ethanol, but acute effects of ethanol on sulphydryls have not been documented in man. Plasma free glutathione and cysteine were therefore measured following the administration of 0.2 g kg-1 ethanol to normal healthy volunteers and chronic alcoholics on disulfiram, where the effects of high concentrations of acetaldehyde can be observed. In both groups, plasma glutathione decreased shortly following ethanol, and a sustained decreased in glutathione was seen in the subjects on disulfiram. In patients on disulfiram, but not the healthy controls, plasma cysteine decreased significantly. The decrease in plasma cysteine was correlated to the rise in acetaldehyde, suggesting that cysteine, but not glutathione, forms an adduct with acetaldehyde in man. We conclude that even moderate doses of ethanol may disturb the sulphydryl homeostasis and could interfere with biologically important processes that depend on sulphydryl groups.