Increased synthesis of systemic prostacyclin in cirrhotic patients

A Review of Terlipressin in Hepatorenal Syndrome: Targeting Endothelial Dysfunction and Subsequent Cardiovascular Adverse Events

Hepatorenal syndrome (HRS) is a serious complication of decompensated liver cirrhosis that results in acute kidney injury (AKI). The mortality rate is high. Endothelial dysfunction secondary to liver cirrhosis is a key driver of the development of portal hypertension, which is eventually complicated by ascites and HRS. Ultimately, splanchnic vasodilation and excess gut lymph production result in ascites, low effective arterial blood volume, and maladaptive compensatory mechanisms that contribute to renal hypoperfusion and injury. While the only curative treatment is liver transplantation, vasoconstrictors and albumin have been the mainstay of treatment for candidates who are ineligible or waiting for transplantation. On September 14, 2022, terlipressin, a V1 vasopressin receptor agonist, was approved by the Food and Drug Administration for the treatment of HRS-AKI. In clinical trials, terlipressin plus albumin have been superior to albumin alone and equivocal to noradrenaline plus albumin in renal function improvement. Terlipressin, however, does not improve survival, is costly, and is associated with severe adverse events-including severe cardiac and vascular complications. The aim of this review is to provide an overview of terlipressin pharmacology, adverse events-with a focus on cardiovascular complications-and comparative randomized controlled trials that resulted in the Food and Drug Administration's approval of terlipressin. New literature since its approval and ongoing clinical trials will also be highlighted.

Multiscale Structured Trimetal Oxide Heterojunctions for Urinary Metabolic Phenotype-Dependent Screening of Early and Small Hepatocellular Carcinoma

Developing a standardized screening tool for the detection of early and small hepatocellular carcinoma (HCC) through urinary metabolic analysis poses a challenging yet intriguing research endeavor. In this study, a range of intricately interlaced 2D rough nanosheets featuring well-defined sharp edges is fabricated, with the aim of constructing diverse trimetal oxide heterojunctions exhibiting multiscale structures. By carefully engineering synergistic effects in composition and structure, including improved adsorption, diffusion, and other surface-driven processes, the optimized heterojunctions demonstrate a substantial enhancement in signal intensity compared to monometallic or bimetallic oxides, as well as fragmented trimetallic oxides. Additionally, optimal heterojunctions enable the extraction of high-quality urinary metabolic fingerprints using high-throughput mass spectrometry. Leveraging machine learning, discrimination of HCC patients from high-risk and healthy populations achieves impressive performance, with area under the curve values of 0.940 and 0.916 for receiver operating characteristic and precision-recall curves, respectively. Six crucial metabolites are identified, enabling accurate detection of early, small-tumor, alpha-fetoprotein-negative HCC (93.3%-97.3%). A comprehensive screening strategy tailored to clinical reality yields precision metrics (accuracy, precision, recall, and F1 score) exceeding 95.0%. This study advances the application of cutting-edge matrices-based metabolic phenotyping in practical clinical diagnostics.

Etiology and Management of Edema: A Review

The development of peripheral edema can often pose a significant diagnostic and therapeutic challenge for practitioners due to its association with a wide variety of underlying disorders ranging in severity. Updates to the original Starling's principle have provided new mechanistic insights into edema formation. Additionally, contemporary data highlighting the role of hypochloremia in the development of diuretic resistance provide a possible new therapeutic target. This article reviews the pathophysiology of edema formation and discusses implications for treatment.

Update on hepatorenal Syndrome: Definition, Pathogenesis, and management

Hepatorenal syndrome (HRS) is acute kidney injury (AKI) that occurs without evidence of structural abnormalities in the kidneys in patients with liver disease. It is thought to be due to splanchnic vasculature dilatation that is associated with intense increase of renal arteries' tone, leading to renal cortex ischemia and AKI. Nitric oxide, endotoxins, neurohormonal changes, bacterial infection, high serum bilirubin and bile acids are examples for factors contributing to HRS development. Nevertheless, other unknown factors may have role in HRS pathophysiology. Hence, further discussion and research are needed to clearly understand HRS. Plasma volume restoration and vasoconstrictors are the cornerstone of HRS treatment. Others such as octreotide, noradrenaline, infection control, systemic inflammatory response prevention, shunting, and renal replacement therapy are currently used to manage HRS. Liver or combined liver and kidney transplantation is currently the ultimate cure for HRS. This review was written to help in better understanding the pathogenesis, diagnosis, and treatment options for HRS.

Treatment Barriers in Portopulmonary Hypertension

Portopulmonary hypertension (PoPH) is a form of pulmonary arterial hypertension (PAH) that can develop as a complication of portal hypertension. Treatment of PoPH includes PAH-specific therapies, and in certain cases, such therapies are necessary to facilitate a successful liver transplantation. A significant number of barriers may limit the adequate treatment of patients with PoPH and explain the poorer survival of these patients when compared to patients with other types of PAH. Until recently, only one randomized controlled trial has included PoPH patients, and the majority of treatment data have been derived from relatively small observational studies. In the present article, we review some of the barriers in the treatment of patients with PoPH and implications for liver transplantation.

Hepatorenal syndrome: an update

Hepatorenal syndrome (HRS) is the development of renal failure in patients with chronic previous liver disease, without clinical or laboratory evidence of previous kidney disease. It affects up to 18% of cirrhotic patients with ascites during the first year of follow-up, reaching 39% in five years and presenting a survival of about two weeks after its establishment. HRS diagnosis is based on clinical and laboratory data. The occurrence of this syndrome is related to the mechanism for ascites development, involving vasoconstriction, low renal perfusion, water and sodium retention, increased plasma volume, and consequent overflow at the splanchnic level. Renal vasoactive mediators like endothelin 1, thromboxane A2, and leukotrienes are also involved in the genesis of this syndrome, which culminates in functional renal insufficiency. The treatment of choice can be pharmacological or surgical, although liver transplantation is the only permanent and effective treatment, with a four-year survival rate of up to 60%. Liver function recovery is usually followed by renal failure reversion. Early diagnosis and timely therapeutics can increase life expectancy for these patients while they are waiting for liver transplantation as a definitive treatment.

Suppressive effect of ursodeoxycholic acid on type IIA phospholipase A2 expression in HepG2 cells

Phospholipase A(2) IIA (PLA(2)IIA), which plays a crucial role in arachidonic acid metabolism and in inflammation, is upregulated under various pathological conditions, including in the gallbladder and gallbladder bile from patients with multiple cholesterol gallstones, in the liver and kidney of rats with cirrhosis, as well as in the colonic tissue of animals treated with a chemical carcinogen. The administration of ursodeoxycholic acid (UDCA) partially attenuated the PLA(2)IIA expression level in these different models. The aim of this study was to investigate the modulatory effect of UDCA on the PLA(2)IIA expression level at the cellular level. The HepG2 cells were selected to investigate the direct inhibitory effect of UDCA on PLA(2)IIA expression level. The proinflammatory cytokines (interleukin-6 and tumor necrosis factor alpha) -induced PLA(2)IIA expression in HepG2 cells was partially inhibited by the presence of UDCA in a dose-dependent fashion. The effect of UDCA on proinflammatory cytokines-induced PLA(2)IIA expression occurred at the transcriptional level. In addition, among the bile acids tested, this inhibitory effect was UDCA-specific. In conclusion, this study supports the possible alteration of arachidonic acid metabolism and PLA(2)IIA expression level, in particular, as the protective action of UDCA in patients with chronic liver disease.

Effects of vasopressin on portal-systemic collaterals of cirrhotic rats

OBJECTIVE

Arginine vasopressin (AVP) exerts a constrictive effect on the portal-systemic collaterals of non-cirrhotic portal hypertensive rats, but its effect on cirrhotic rats is unknown. The aim of this study was to investigate the response of AVP and the modulatory roles of nitric oxide and prostaglandin on collaterals of common bile duct-ligated (BDL) cirrhotic rats.

MATERIAL AND METHODS

The collateral vascular responsiveness to graded concentrations of AVP (10(-10) - 3 x 10(-7) M) was tested by an in situ collateral perfusion system pretreated with Nomega-nitro-L-arginine (L-NNA, 100 microM), indomethacin (INDO, 10 microM), or both. The collateral responses to AVP with the pretreatment of a vasopressin V1 receptor antagonist d(CH2)5Tyr(Me) arginine vasopressin or a V2 receptor agonist 1-desamino-8-D-arginine vasopressin (DDAVP, 10(-10) - 3 x 10(-7) M) were also evaluated.

RESULTS

The perfusion pressure of collaterals was significantly increased by AVP, and this effect was inhibited by the addition of the V1 receptor antagonist. DDAVP had no effect on the collaterals. Incubation with L-NNA or L-NNA plus INDO, but not INDO alone, significantly potentiated the constrictive effects of AVP. The constrictive effect of AVP in the combination group was similar to that in the L-NNA alone group.

CONCLUSIONS

The results show that AVP produces a direct vasoconstrictive effect on the portal-systemic collaterals of BDL cirrhotic rats. The constrictive effect of AVP is mediated by the vasopressin V1, instead of V2, receptors. Nitric oxide may play a more important role than prostaglandin in modulating the collateral vascular response to AVP in BDL cirrhotic rats.

Effect of prostaglandin E2 and prostaglandin I2 on PDGF-induced proliferation of LI90, a human hepatic stellate cell line

Hepatic stellate cells (HSC) are central to liver fibrosis. The eicosanoid pathway and cyclooxygenase-2 (COX-2) may be an important signaling mechanism in HSC. We investigated the role of COX-2, prostaglandin E(2) (PGE(2)) and prostaglandin I(2) (PGI(2)) in proliferation of LI90, an immortalized cell line of HSC. Our results showed that COX-2 was upregulated by platelet-derived growth factor (PDGF), a mitogen in HSC. COX-2 was responsible for the production of PGE(2) and PGI(2) in PDGF-stimulated LI90 cells. Furthermore, we demonstrated that COX-2 and PGE(2) mediated the proliferative response of LI90 to PDGF while synthetic analogue of PGI(2) exhibited anti-proliferative effect. Our findings suggest complex interactions of prostaglandins in liver fibrogenesis. In vivo studies using animal models are needed to elucidate the effect of COX-2 inhibition by non-steroidal anti-inflammatory drugs or COX-2 inhibitor in hepatic fibrosis.

Cyclooxygenase-2 and inducible nitric oxide synthase in omental arteries harvested from patients with severe liver diseases: immuno-localization and influence on vascular tone

OBJECTIVE

To investigate the expression of inducible cyclooxygenase (COX-2) and inducible nitric oxide synthase (iNOS) and the role of vasodilatory prostanoids and endogenous nitric oxide (NO) in small omental arteries harvested from patients with severe liver diseases.

DESIGN

Ex vivo study of resistance arteries. SETTING. Intensive care unit.

PATIENTS

Twenty patients undergoing liver transplantation for fulminant hepatic failure (FHF, n=6), cirrhogenous viral hepatitis (CH, n=6) and limited hepatocarcinoma (controls, n=8).

INTERVENTIONS

Western blot and immunohistochemical labeling for assessment of COX-2 and iNOS expression and localization and ex vivo vascular reactivity studies.

MEASUREMENTS AND RESULTS

Significant upregulation of COX-2 and iNOS expressions were detected in arteries from FHF and CH patients with a greater increase in the former than in the latter. Ex vivo contractile responses to norepinephrine and the thromboxane A(2) analog, U46619, were not significantly different between patients with severe liver dysfunction and controls. Exposure to either the NO-synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME), the cyclooxygenase inhibitor, indomethacin, or their combination did not significantly modify contractions of agonists in controls and CH patients. In FHF, the specific COX-2 inhibitor, N-(2-cyclohexyloxy-4-nitrophenyl) methanesulfonamide (1 micro m/l), but not L-NAME, significantly enhanced the maximal effect ( p<0.01) and the sensitivity ( p<0.01) to norepinephrine.

CONCLUSIONS

COX-2 and iNOS are upregulated in omental arteries from patients with cirrhogenous hepatitis and fulminant hepatic failure. Whereas neither NO nor vasodilatory prostaglandins seem to play a major role in counteracting arterial contractility of arteries from control patients, COX-2 derivatives are involved in lowering the arterial contractility of vessels harvested from FHF patients.

Inhibition of prostacyclin by indomethacin ameliorates the splanchnic hyposensitivity to glypressin in haemorrhage-transfused common bile duct-ligated rats

Prostacyclin (PGI2) is an important contributor to the mediation of hyporeactivity to vasoconstrictors and the development of hyperdynamic circulation in portal hypertensive states. Inhibition of PGI2 synthesis in haemorrhage-transfused partially portal vein-ligated rats could ameliorate the splanchnic hyposensitivity to glypressin, a long-acting vasopressin analogue. This study investigated whether the hyposensitivity to glypressin also exists in rats with common bile duct ligation (BDL) and whether the inhibition of PGI2 synthesis by indomethacin could potentiate the portal-hypotensive effect of glypressin in bleeding BDL rats. Two series of BDL rats were used. Series 1 investigated the haemodynamic effects of low dose glypressin (0.07 mg kg-1) in BDL rats with or without bleeding by catheterization. In series 2, haemodynamic parameters were measured in stable or bleeding BDL rats that were receiving intravenously high dose glypressin (0.2 mg kg-1) or indomethacin (5 mg kg-1) followed by high dose glypressin. In rats with a hypotensive haemorrhage, 4.5 mL of blood was withdrawn and 50% of the withdrawn blood was reinfused before the administration of glypressin or indomethacin. Splanchnic hyposensitivity to glypressin was demonstrated in haemorrhage-transfused BDL rats receiving high, but not low, doses of glypressin. Indomethacin infusion did not cause significant systemic and portal haemodynamic changes in bleeding BDL rats (P > 0.05). The addition of indomethacin significantly enhanced the portal-hypotensive effects of glypressin (P < 0.05) and potentiated the increases in mean arterial pressure induced by glypressin infusion (P < 0.001) in bleeding BDL rats. Splanchnic hyposensitivity to glypressin observed in haemorrhage-transfused BDL rats could be ameliorated by the addition of indomethacin, suggesting a role of endogenous PGI2 in its pathophysiology.

Effects of prostacyclin inhibition on splanchnic hyposensitivity to glypressin in a hemorrhage-transfused rat model of portal hypertension

BACKGROUND

Hyposensitivity to vasopressin is a well-documented phenomenon in animals with portal hypertension and patients with cirrhosis and hemorrhage. Similar findings exist with infusion of glypressin (a long-acting vasopressin analogue), and this phenomenon could be ameliorated by inhibition of nitric oxide (NO) synthase. Besides NO, excessive formation of prostacyclin (PGI2) has been shown to play an important role in the development of hyperdynamic circulation and the mediation of hyporeactivity to vasoconstrictors in portal-hypertensive states. This study was designed to investigate whether the blockade of PGI2 activity by indomethacin infusion could enhance the portal-hypotensive effect of glypressin in portal-hypertensive rats with bleeding.

METHODS

Portal hypertension was induced by partial portal vein ligation (PVL). Fourteen days after operation systemic and portal hemodynamics were measured in stable or bleeding PVL rats receiving intravenous glypressin (0.07 mg/kg) or indomethacin (5 mg/kg) followed by glypressin infusion. In rats with a hypotensive hemorrhage 4.5 ml of blood was withdrawn, and 50% of the withdrawn blood was reinfused before the administration of glypressin or indomethacin.

RESULTS

Splanchnic hyposensitivity to glypressin was shown in hemorrhage-transfused PVL rats. Indomethacin infusion did not cause significant systemic and portal-hemodynamic changes in bleeding PVL rats (P > 0.05). The addition of indomethacin significantly enhanced the portal-hypotensive effects of glypressin and potentiated the increases in mean arterial pressure induced by glypressin infusion in bleeding PVL rats.

CONCLUSIONS

The improvement of splanchnic hyposensitivity to glypressin in a hemorrhage-transfused rat model of portal hypertension by the administration of indomethacin suggests that PGI2 has in the development of this hyposensitivity.

Hepatopulmonary syndrome and liver transplantation: a review of the peroperative management of seven paediatric cases

Until recently, hypoxaemia was considered as a relative contraindication for liver transplantation. The hepatopulmonary syndrome associated with a right to left shunt of blood through the lungs is reversible in adults and children after correction of the cirrhosis by liver transplantation. However, concerns have been raised regarding the risks of anaesthesia in such hypoxaemic patients. Since the peroperative management of children undergoing liver transplantation and suffering from hepatopulmonary syndrome and severe hypoxemia has never been described, we report here our experience in seven children. Despite the fact that severe arterial desaturation was recorded throughout the procedure, no major complications were recorded peroperatively. The postoperative intubation time was 58 +/- 21 h, five children being extubated while still hypoxaemic. All seven patients reversed their hepatopulmonary syndrome after a mean postoperative period of 24 +/- 10 weeks. This shows that liver transplantation can be successfully achieved in severely hypoxaemic children and that postoperative correction of the right to left shunt is then obtained.

Increased renal and vascular cytosolic phospholipase A2 activity in rats with cirrhosis and ascites

Indirect evidence suggests that the renal and vascular production of prostaglandins is increased in cirrhosis with ascites. However, the activity of the enzymes regulating the prostaglandin pathway has not been investigated in cirrhosis. The aim of the current study was to determine the activity of phospholipase A2 (PLA2), the key enzyme in the regulation of prostaglandin synthesis, in kidney and vascular tissue obtained from rats with carbon tetrachloride-induced cirrhosis and ascites (n = 9) and control rats (n = 6). PLA2 activity was assayed in vitro using [14C]arachidonyl-phosphatidylcholine (PC) and [14C]arachidonyl-phosphatidylethanolamine (PE) as substrates in the presence of Ca2+. Kidneys from cirrhotic rats had significantly higher PLA2 activity compared with control rats, with both PC and PE (35 +/- 5 and 40 +/- 6 vs. 21 +/- 2 and 26 +/- 3 pmol/mg/min, respectively; P < .05 for both). PLA2 activity was increased in the renal cortex as well as in the renal medulla. Fractionation of the kidney extracts by Mono-Q anion-exchange chromatography showed that the elution position of PLA2 activity corresponded to the cytosolic PLA2 isoform (cPLA2). Increased amounts of cPLA2 protein were found in kidney extracts immunoblotted with an anti-cPLA2 antibody However, reverse-transcriptase polymerase chain reaction (RT-PCR) analysis did not detect any difference in cPLA2 mRNA. PLA2 activity was also higher in aortic tissue from cirrhotic rats than in controls (PC 38 +/- 5 vs. 26 +/- 1 and PE 66 +/- 8 vs. 41 +/- 3 pmol/mg/min; P < .05 for both). Incubation of renal and aortic extracts from cirrhotic rats with anti-cPLA2 antibody reduced PLA2 activity by 64% and 88%, respectively. In conclusion, PLA2 activity is increased in kidneys and vascular tissue from cirrhotic rats with ascites. This can be accounted for by an induction of cPLA2, which would mediate, at least in part, the increased renal and vascular production of prostaglandins in cirrhosis.

Clinical pharmacokinetics of sulindac. A dynamic old drug

Sulindac is a nonsteroidal anti-inflammatory drug (NSAID) of the indene acetic acid class. The absorption of sulindac is rapid when given orally. Sulindac is reversibly metabolised to sulindac sulphide which has anti-inflammatory and analgesic properties and is irreversibly metabolised to sulindac sulphone which has been suggested to possess antiproliferative effects against tumours. Sulindac and its sulphide and sulphone metabolites bind extensively to plasma albumin. Sulindac is eliminated following bio-transformation; sulindac and sulindac sulphone and their respective glucurooconjugated metabolites are excreted in urine; however only a small amount of the sulindac sulphide metabolite is eliminated in urine. Following long term twice daily administration both sulindac and its metabolites accumulate in plasma. Both patients with cirrhosis and the elderly demonstrate elevated concentrations of all species upon long term sulindac administration as compared with a single dose. The disposition of sulindac and its metabolites may be tied to renal function. In end-stage renal disease, increased free fractions of all species and accumulation of the sulphide and sulphone metabolites, and to a lesser extent sulindac, occurs. Significant drug interactions have been demonstrated for dimethylsulphoxide, cyclosporin, furosemide (frusemide), hydrochlorothiazide, methotrexate and cholestyramine.

Liver cirrhosis induces renal and liver phospholipase A2 activity in rats

Maintenance of renal function in liver cirrhosis requires increased synthesis of arachidonic acid derived prostaglandin metabolites. Arachidonate metabolites have been reported to be involved in modulation of liver damage. The purpose of the present study was to establish whether the first enzyme of the prostaglandin cascade synthesis, the phospholipase A2(PLA2) is altered in liver cirrhosis induced by bile duct excision. The mRNA of PLA2(group I and II) and annexin-I a presumptive inhibitor of PLA2 enzyme was measured by PCR using glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as an internal standard. The mean mRNA ratio of group II PLA2/GAPDH was increased in liver tissue by 126% (P < 0.001) and in kidney tissue by 263% (P < 0.006) following induction of liver cirrhosis. The increase in group II PLA2 mRNA in cirrhotic animals was reflected by an increase in PLA2 protein and enzyme activity in both liver and kidney tissues. Since the mRNA of group I PLA2 was not detectable and Group IV PLA2 activity measured in liver and kidney tissue samples was very low and not changed following induction of cirrhosis, it is likely that the major PLA2 activity measured in liver and kidney corresponds to group II PLA2 enzyme. The mean mRNA ratio of annexin-I/GAPDH was increased in liver tissue by 115% (P < 0.05) but unchanged in kidney tissue following induction of cirrhosis. The protein content of annexin-I and -V were not affected by bile duct excision in liver and kidney tissue indicating that upregulation of group II PLA2 activity was not due to downregulation of annexin-I or -V. Group II PLA2 activity of glomerular mesangial cells stimulated by interleukin-1 beta was enhanced by bile juice and various bile salts. In conclusion, activity of group II PLA2 is upregulated partly due to enhanced transcription and translation in cirrhosis and is furthermore augmented by elevated levels of bile salts.

The hepatorenal syndrome

Hepatorenal syndrome may occur in any form of severe liver disease. It appears less common in children than adults, but still carries a poor prognosis. There are several factors involved in its aetiology, including a decreased renal perfusion pressure, activation of the renal sympathetic nervous system and increased synthesis of several vasoactive mediators, which may modulate glomerular filtration by acting as both renal vasoconstrictors and dynamic regulators of the glomerular capillary ultrafiltration coefficient, through their action on mesangial cells. This review will discuss the pathophysiology of the hepatorenal syndrome and some of the principles of management of patients with renal failure and severe liver disease. The role of renal support and liver transplantation will also be covered.

Altered levels of urinary prostanoids in lead-exposed workers

This paper describes the alteration of the urinary excretion of prostanoids in workers occupationally exposed to lead. For this purpose, the following groups were studied: Group 1 (n = 62): controls; Group 2 (n = 29): risk group; and Group 3 (n = 69): exposed group. Urine samples were collected for prostanoid analysis and lead blood levels were analyzed. Our results demonstrate that urinary excretion of prostanoids is already altered even at levels of lead in blood = 200 micrograms/l. Owing to their sensitivity, urinary prostanoids could be useful markers of early renal changes associated with lead exposure. However, underlying mechanisms should be elucidated and the health significance of such changes should be assessed before any conclusion is drawn.

Changes in prostaglandin E2 and F2 alpha during vitellogenesis in the Florida crayfish Procambarus paeninsulanus

While the role of eicosanoids in reproduction in vertebrate species has been well established, the role of these fatty acid derivatives in invertebrate species has not been as well characterized. The purpose of this study was to investigate changes in prostaglandins E2 and F2 alpha during vitellogenesis in the crayfish Procambarus paeninsulanus. In homogenates of crayfish ovaries taken at various stages of development, the rate of prostaglandin synthesis and the concentrations of prostaglandins E2 and F2 alpha increased during the final stages of yolk production just prior to ovulation. A gradual increase in prostaglandin E2 amounts was observed throughout the progression of vitellogenesis. The data suggests the possible involvement of prostaglandins in regulatory events associated with vitellogenesis and the induction of ovulation in Procambarus paeninsulanus.

Increased serum nitrite and nitrate levels in patients with cirrhosis: relationship to endotoxemia

Nitric oxide derived from vascular endothelium is a potent vasodilator that plays a key role in the homeostasis of blood pressure. Because cirrhotic patients tend to have low arterial pressure, we measured in 51 patients and 10 control subjects serum nitrite and nitrate levels as an index of in vivo nitric oxide generation. We also measured plasma endotoxin, a substance frequently increased in cirrhotic patients and known to induce nitric oxide synthesis. Cirrhotic patients showed significant increases in serum nitrite/nitrate and plasma endotoxin compared with controls. Values were particularly increased in patients with decompensated cirrhosis, as manifested by ascites with or without functional kidney failure. High serum nitrite/nitrate levels were associated with high plasma renin activity, high aldosterone and antidiuretic hormone levels and low urinary excretion of sodium. In addition, serum nitrite/nitrate levels significantly correlated with endotoxemia. Oral administration of colistin to 15 cirrhotic patients reduced significantly plasma endotoxin levels (p < 0.01) and serum nitrite/nitrate levels (p < 0.05). Because endotoxin enhances the expression of inducible nitric oxide synthase, our results suggest that circulating endotoxin in cirrhosis is responsible for excessive synthesis and release of nitric oxide by the vasculature. These findings might explain the hemodynamic dysfunction seen in cirrhotic patients.

Role of prostacyclin in hemodynamic alterations in conscious rats with extrahepatic or intrahepatic portal hypertension

Although prostaglandins are thought to be involved in the hyperdynamic circulation of portal hypertension, the role of this substance has not been elucidated. Dose-response curves, the hemodynamic effects of prostacyclin (20 micrograms/kg) and its inhibitor indomethacin and measurements of plasma and urinary levels of 6-keto-prostaglandin F1 alpha were compared in three groups of six rats each: normal, with portal vein stenosis and with secondary biliary cirrhosis. Plasma and urinary levels of 6-keto-prostaglandin F1 alpha were higher in rats with portal vein stenosis and cirrhotic rats than in normal rats. Dose-response curves showed similar maximal decreases in arterial pressure in the three groups, whereas the maximal increase in portal pressure was less marked in cirrhotic rats than in normal rats and rats with portal vein stenosis. In normal rats, prostacyclin increased cardiac output by 21% and portal pressure by 41%. Similar increases were observed in rats with portal vein stenosis. In contrast, prostacyclin did not affect cardiac output and portal pressure in cirrhotic rats. Indomethacin induced a more marked vasoconstrictive effect in normal rats than in cirrhotic rats. This study shows that prostacyclin plays a role in the hemodynamic alterations in portal hypertension. Moreover, the hyporeactivity observed in cirrhotic rats suggests that prostacyclin plays a major role in the circulatory changes of portal hypertension due to chronic liver disease.

Involvement of nitric oxide and prostaglandins in gastric mucosal hyperemia of portal-hypertensive anesthetized rats

This study investigates the effects of inhibition of nitric oxide synthesis by NG-nitro-L-arginine methyl ester (L-NAME), the inhibition of prostaglandin synthesis with indomethacin and the combined effects on gastric mucosal hyperemia of ketamine-anesthetized rats with portal hypertension induced by partial portal vein ligation. The hydrogen gas-clearance technique was used for measurement of gastric mucosal blood flow. Blood pressure increased with L-NAME administration in a similar manner in portal-hypertensive and sham-operated rats. Low doses of L-NAME (1 and 3 mg/kg, intravenously) caused a significant and dose-dependent reduction in gastric mucosal blood flow in portal-hypertensive rats but had no effect on sham-operated animals. With a higher dose of L-NAME (13 mg/kg, intravenously), a significant decrease in gastric mucosal blood flow was observed in both portal-hypertensive and sham-operated rats. Indomethacin pretreatment (5 mg/kg, subcutaneously) caused a significant decrease in basal gastric mucosal blood flow of portal-hypertensive rats but did not modify this parameter in sham-operated animals. In sham-operated rats pretreated with indomethacin, the lower dose of L-NAME (3 mg/kg) did not significantly modify basal gastric mucosal blood flow. Likewise, pretreatment with indomethacin in sham-operated rats did not augment the significant reduction in gastric mucosal blood flow produced by the higher dose of L-NAME. In portal-hypertensive rats the significant dose-dependent reduction in gastric mucosal blood flow induced by L-NAME (3 and 13 mg/kg) was not significantly altered by pretreatment with indomethacin.(ABSTRACT TRUNCATED AT 250 WORDS)

Circulating levels of endothelin in cirrhosis

BACKGROUND

Current information concerning endothelin in cirrhosis is conflicting. Plasma endothelin concentration has been found to be increased in some studies and normal or reduced in others. The present study was aimed to investigate the plasma levels of endothelin in cirrhosis and to assess whether it is involved in the renal and hemodynamic disturbances and neurohumoral changes present in this condition.

METHODS

Renal function, plasma renin activity, and plasma concentration of aldosterone, norepinephrine, antidiuretic hormone, atrial natriuretic factor, and endothelin were measured in 9 healthy subjects, 7 compensated cirrhotics, and 25 cirrhotics with ascites (10 with functional renal failure).

RESULTS

Cirrhotics with ascites with and without functional renal failure showed higher endothelin levels (15.6 +/- 6.4 and 15.7 +/- 4.6 pg/mL, respectively; mean +/- SD) than compensated cirrhotics (6.4 +/- 1.8 pg/mL) and healthy subjects (3.4 +/- 1.0 pg/mL) (analysis of variance, F = 21.84; P < 0.001). These patients also showed higher plasma levels of renin, aldosterone, norepinephrine, antidiuretic hormone, and atrial natriuretic factor, although plasma endothelin levels only correlated significantly with plasma atrial natriuretic factor (r = 0.73, P < 0.001) and antidiuretic hormone concentrations (r = 0.59, P < 0.001). In 7 additional nonazotemic cirrhotics with ascites, plasma renin activity and the plasma concentration of aldosterone and endothelin were measured before and 24 hours after the intravenous administration of a saline solution of human serum albumin. Volume expansion markedly suppressed renin and aldosterone but not endothelin (21.03 +/- 7.34 vs. 23.97 +/- 14.29 pg/mL).

CONCLUSIONS

Circulating plasma levels of endothelin are elevated in cirrhosis with ascites and do not decrease following plasma volume expansion.

Changes of systemic prostacyclin and thromboxane A2 in sodium taurocholate- and cerulein-induced acute pancreatitis in rats

Systemic prostacyclin and thromboxane A2 production in rat experimental acute pancreatitis has been evaluated by measuring the urinary excretion of the 2,3-dinor 6-keto prostaglandin F1 alpha and 2,3-dinor thromboxane B2, respectively. Acute pancreatitis was induced by intraductal administration of 4.5% sodium taurocholate (0.1 ml/100 mg body weight) and intravenous cerulein perfusion (5 micrograms/kg/hr) for 6 hr, respectively. Urinary excretion of 2,3-dinor 6-keto prostaglandin F1 alpha and 2,3-dinor thromboxane B2 were much more important in sodium taurocholate- than in cerulein-induced acute pancreatitis. These data confirm an altered prostacyclin and thromboxane metabolism occurring in experimental acute pancreatitis. Phospholipase A2 activity and the effect of gabexate mesilate on the arachidonate metabolism were also evaluated.

Altered systemic and tissue prostacyclin in cerulein induced acute pancreatitis in rats

Prostacyclin metabolism in rat acute pancreatitis was evaluated by measuring the tissue levels of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and the urinary excretion of 2, 3-dinor 6-keto-PGF1 alpha. Acute pancreatitis was induced by i.v. cerulein perfusion and was confirmed by the pancreas enzyme changes and the histological findings. Significantly enhanced tissue and urinary prostacyclin levels were found in acute pancreatitis rats, when compared to the controls. Concomitantly, an enhanced tissue phospholipase A2 (PLA2) activity was also found. These data show the importance of 2, 3-dinor PGF1 alpha as an inflammatory marker in cerulein-induced pancreatitis.

Altered levels of tissue and urinary prostacyclin in rats subjected to pancreas transplantation

Significant increases of TXB2 and PGE2 are reported to occur in pancreas transplantation. These increases are prevented with scavengers of oxygen-free radicals. In this communication, we report on changes of prostacyclin metabolites such as tissue 6-keto prostaglandin F1 alpha and urinary 2,3-dinor 6-keto prostaglandin F1 alpha in rats subjected to pancreas transplantation after different periods of organ cold preservation ischemia as well as the effect of superoxide dismutase (SOD) on these changes. For this purpose, male Lewis rats were classified as follows: Group I, Control; Group II, syngenic pancreas transplantation after 15 min of organ preservation in Collins solution at 4 degrees C; Group III, same as II but with 12 hours of organ preservation; Group IV, same as III, but with SOD pretreatment. Results have shown significant posttransplantation increases of both tissue 6-keto PGF1 alpha and urinary 2, 3 dinor 6-keto PGF1 alpha, the latter being a useful marker to evaluate systemic prostacyclin (PGI2) production by rat pancreas. This effect was prevented when the organ had been exposed to SOD during the period of cold preservation ischemia. These results confirm the implication of oxygen-free radicals (OFR) in the ischemia-reperfusion process associated to rat pancreas transplantation leading to enhanced arachidonic acid metabolism.

Systemic and renal production of thromboxane A2 and prostacyclin in decompensated liver disease and hepatorenal syndrome

To assess the role of altered renal and systemic production of thromboxane A2 and prostacyclin in the hepatorenal syndrome, urinary excretion of their major renal and extrarenal metabolites was measured in patients with compensated and decompensated liver disease, chronic renal failure, and hepatorenal syndrome. Urinary excretion rates of all prostanoids (renal and extrarenal) were increased in subjects with liver disease compared with normal controls. Moreover, they were considerably higher in subjects with severe hepatic decompensation but good renal function compared with those with hepatorenal syndrome. In contrast, the excretion rate of all metabolites was reduced in patients with chronic renal failure. The excretion rate of all metabolites was markedly elevated during the early stages of hepatorenal syndrome and decreased in parallel with creatinine clearance. When corrected for creatinine clearance, there was a strong correlation between prostanoid excretion and serum bilirubin in subjects with liver disease; there was no difference, however, in the excretion of renal and extrarenal prostanoids between hepatorenal syndrome and severe hepatic decompensation. It is concluded that hepatic decompensation is associated with a progressive increase in prostanoid excretion but that changes in production of prostacyclin or thromboxane A2 are unlikely to be major factors in the pathogenesis of the hepatorenal syndrome.

Renal prostacyclin influences renal function in non-azotemic cirrhotic patients treated with furosemide

The influence of prostaglandins on renal function changes induced by furosemide was analyzed in 21 non-azotemic cirrhotic patients with ascites. Patients were studied in two periods of 120 min immediately before and after furosemide infusion (20 mg, ev). Furosemide caused an increase in creatinine clearance in 15 patients (group A: 99 +/- 7 vs. 129 +/- 5 ml/min; mean +/- S.E.) and a reduction in the remaining six (group B: 102 +/- 13 vs. 71 +/- 9 ml/min). Parallel changes were observed in the urinary excretion of 6-Keto-prostaglandin-F1 alpha (metabolite of renal prostacyclin) which augmented after furosemide in 14 of the 15 patients from group A (478 +/- 107 vs. 1034 +/- 159 pg/min, p less than 0.001) and decreased in all patients from group B (1032 +/- 240 vs. 548 +/- 136 pg/min, p less than 0.05). In contrast, the urinary excretion of prostaglandin E2 was stimulated by furosemide in all patients (group A, 92 +/- 19 vs. 448 +/- 60 pg/min, p less than 0.001; and group B, 209 +/- 63 vs. 361 +/- 25 pg/min, p less than 0.05). In all of the patients furosemide-induced changes (post- minus pre-furosemide values) in creatinine clearance were closely correlated in a direct and linear fashion with those in 6-Keto-prostaglandin-F1 alpha (r = 0.74; p less than 0.001). These changes were associated with a higher furosemide-induced natriuresis in group A than in group B (641 +/- 68 vs. 302 +/- 46 mumol/min, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aetiology and pathophysiology of chronic liver disorders

The aetiology of chronic liver disease covers a wide range of congenital or acquired abnormalities of the hepatocellular biochemical network. Although our knowledge has considerably increased in recent years, the aetiology of chronic liver disease often remains obscure. Acquired irreversible disturbances of normal liver function can be mediated by hepatotrophic viruses, chemicals, chronic oxygen depletion, or interference with the immune system. Considerable progress has been made in the detection and characterisation of hepatitis B, C, and D viruses as causative agents of chronic active hepatitis. Alcohol abuse remains the predominant cause of chronic liver disease in the Western world. The targets of autoantibodies used to diagnose autoimmune diseases of the liver and primary biliary cirrhosis continue to be biochemically defined. Their significance for the aetiology of the disease, however, remains to be established. Nonparenchymal cells play an important role in the sequence of events following hepatocellular injury and ultimately leading to liver cirrhosis. They release vasoactive compounds, cytokines, and other important mediators, and participate in the modulation of the extracellular matrix that is characteristic of liver fibrosis and cirrhosis. The biochemical basis of liver cell necrosis remains poorly defined. In spite of recent progress, and the detection of some new pathogenic principles that help in the understanding of the complications of chronic liver disease such as portal hypertension, oesophagogastric variceal bleeding, portosystemic encephalopathy, ascites, and other metabolic disturbances, many questions concerning the aetiology and pathophysiology of chronic liver disease and its complications remain to be answered.

Systemic and regional hemodynamics in patients with liver cirrhosis and ascites with and without functional renal failure

Systemic, femoral, and renal hemodynamics were evaluated in 7 control subjects and 20 cirrhotic patients with ascites, 14 of them without (group A) and 6 with (group B) functional renal failure. Hyperdynamic systemic circulation, increased plasma volume, and hyperreninism were present in groups A and B. These changes were more severe in group B, which showed, as compared with group A, lower total vascular resistances and mean arterial pressure together with increased cardiac index and plasma renin activity. Significant differences in regional hemodynamics were also observed between groups. In group A, femoral and renal fractions of cardiac output were respectively increased and reduced as compared with controls. By contrast, in group B, both fractions of cardiac output were reduced when compared either with controls or with group A. In the entire patient group there was a close direct correlation between femoral and renal fractions of cardiac output (r = 0.88; p less than 0.001) and both of them correlated independently with total vascular resistances (r = 0.79; p less than 0.001 in both cases). These results indicate that, in nonazotemic cirrhotics with ascites, vasodilatation in extrasplanchnic areas contributes to the genesis of the hyperdynamic circulation. The presence in group B of a reduced flow to extrasplanchnic territories, in association with an increase of the hyperdynamic circulatory status, suggests that exacerbation of splanchnic vasodilatation is involved in the development of the hepatorenal syndrome. Finally, in cirrhosis, the changes that occur in systemic hemodynamics appear to influence renal function and renal blood flow.

Modern high-performance liquid chromatographic-radioimmunoassay strategies for the study of eicosanoids in biological samples

An evaluation of the most recent literature on the determination of eicosanoids by immunoassay methods confirms that owing to the inherent lack of specificity of many of the antibodies used for this purpose, immunological assays (radioimmunoassay or enzyme immunoassay) are often preceded by solid-phase extraction followed by further purification of the antigens of interest by routine reversed-phase high-performance liquid chromatographic methods. In this way the analytical potential of radioimmunoassay is remarkably enhanced and accuracy and precision of the assay are ensured.

Nonsteroidal antiinflammatory drug-induced renal dysfunction related to inhibition of renal prostaglandins

This article reviews the role of prostaglandins (PG) in maintaining renal function in the face of vasoconstrictive substances and decreased renal blood flow. Inhibition of the synthesis of renal PG by nonsteroidal antiinflammatory drugs (NSAID) may lead to the development of hemodynamically induced renal dysfunction in patients with a decreased effective plasma volume or chronic renal insufficiency. The importance of stimulation of renal PG activity to the action of diuretics and a pharmacodynamic mechanism for NSAID-induced diuretic resistance are presented. Evidence for the relative selectivity of sulindac in inhibiting systemic PG without inhibiting renal PG is also reviewed. Inhibition of renal PG synthesis has been postulated to be a contributing factor for other forms of NSAID-induced renal dysfunction (interstitial nephritis, analgesic-associated nephropathy). The relationship between renal PG inhibition by NSAID and these syndromes is briefly discussed. Considering the frequent use of NSAID, it is important that practitioners are aware of the mechanisms whereby patients may develop NSAID-induced renal dysfunction and that they are able to identify patients at risk.

Renal eicosanoids as determinants of renal function in liver disease

The available data suggest that alterations in renal prostaglandin metabolism participate in the pathogenesis of at least two prominent renal complications of liver disease: (a) sodium retention and (b) HRS. Although the data are highly suggestive, additional studies, including experimental manipulations that augment vasodilatory prostaglandins while diminishing vasoconstrictor metabolites of arachidonic acid, will be required to establish the role of prostaglandins or other arachidonic acid metabolites in mediating these renal abnormalities. The clinical caveat emerging from these observations is that every attempt should be made to avoid prescribing drugs which possess cyclooxygenase inhibitory activity to patients with decompensated liver disease who are sodium-avid.

Reversible acute decrease in renal function by NSAIDs in cirrhosis

The effects of sulindac were compared with those of ibuprofen or naproxen on creatinine clearance and urinary prostanoids in patients with severe alcoholic cirrhosis. Sulindac caused acute declines in all renal parameters in four of five patients. The effect occurred with serum concentrations of the active sulfide metabolite comparable to those in patients with no hepatic impairment. The patient who was not affected had less effects on urinary PGE2 and TxB2 and no effect on 6-keto PGF1 alpha. In this patient, dosing with ibuprofen caused pronounced declines in all urinary prostanoids and a decrease in creatinine clearance. Two other patients treated with ibuprofen and one treated with naproxen also suffered decrements in all parameters. In conclusion, sulindac had suppressant effects on renal prostanoids associated with declines in creatinine clearance in these patients with cirrhosis, indicating a need for similar cautions with its use as with other NSAIDs.

Determination of 2,3-dinor-6-ketoprostaglandin F1 alpha in urine samples by liquid chromatography and radioimmunoassay

A method for 2,3-dinor-6-ketoprostaglandin F1 alpha quantification based on high-performance liquid chromatography-radioimmunoassay is described. Samples are acidified to pH 3 and processed through C18 disposable cartridges. The prostanoids are eluted with methyl formate and further separated on a reversed-phase column using acetonitrile-acetic acid-triethylamine buffer (32:68). Studies of the effect of eluent pH were performed in order to optimize resolution and separation of 2,3-dinor-6-keto-PGF1 alpha from other prostanoids. Eluates were collected and assayed by radioimmunoassay using a heterologous system, with 6-keto-PGF1 alpha as radioligand and an antiserum with high cross-reactivity for 2,3-dinor-6-keto-PGF1 alpha. Sensitivity, precision and accuracy of the assay procedure are reported together with the validation of its specificity. The proposed method has been applied to the determination of this prostacyclin metabolite in human urine.

Renal function abnormalities, prostaglandins, and effects of nonsteroidal anti-inflammatory drugs in cirrhosis with ascites. An overview with emphasis on pathogenesis

The ability of the kidneys to excrete sodium and free water is often impaired in patients with cirrhosis. Sodium retention is a sine qua non for ascites formation. The impairment of water excretion causes hyponatremia and hypo-osmolality. In addition, these patients frequently have functional renal failure caused by intense renal vasoconstriction. The renin-angiotensin-aldosterone system and the sympathetic nervous system, which are activated in most cirrhotic patients with ascites, and a nonosmotic hypersecretion of antidiuretic hormone are important mechanisms of sodium and water retention. Angiotensin II and sympathetic nervous activity may also be involved in the pathogenesis of functional renal failure. The renal production of prostaglandins is increased in cirrhotic patients with ascites as a homeostatic response to antagonize the vascular effect of endogenous vasoconstrictors and the tubular action of antidiuretic hormone. Nonsteroidal anti-inflammatory drugs should, therefore, be administered with caution in these patients because they may induce acute renal failure and water retention. Although sulindac inhibits the renal synthesis of prostaglandins in cirrhotic patients with ascites, it appears to have less effect on renal function than do other nonsteroidal anti-inflammatory drugs administered to these patients.

Role of renal prostaglandins and the effects of nonsteroidal anti-inflammatory drugs in patients with liver disease

Renal prostaglandins have several key functions in patients with severe liver disease and ascites. Increased activity of vasodilatory prostaglandins counters the underlying impairment in renal perfusion and the effects of vasoactive hormones. Prostaglandins also participate in renin secretion, renal diluting ability, sodium excretion, the action of diuretics, and, possibly, the development of the hepatorenal syndrome. Nonsteroidal anti-inflammatory drugs inhibit these compensatory actions of prostaglandins and cause a functional reduction in glomerular filtration rate and an impairment in sodium and fluid excretion. The severity of these nephrotoxic effects depends on the potency of the drug in inhibiting renal prostaglandins and on patient susceptibility. Patients with ascites and avid sodium retention, sodium-restricted diets, or concurrent diuretic use are most at risk. If nonsteroidal anti-inflammatory drugs must be administered to these patients, the type of drug should be carefully selected and renal function should be closely monitored.

Effect of spironolactone on renal prostaglandin excretion in patients with liver cirrhosis and ascites

The effect of spironolactone on the urinary excretion of prostaglandins was studied in patients with liver cirrhosis and ascites. Patients were kept in bed and given a sodium-restricted diet for at least 4 days before spironolactone treatment was considered. Starting from the 5th day of protocol, patients were treated with this diuretic if their spontaneous weight loss had been less than 600 g during the 2 previous days. Patients were distributed in groups according to weight loss during the first 4 days on diuretic therapy: Group I (high responders), II (medium responders) and III (low responders). Group I patients showed higher basal values (4th day of protocol) of urinary sodium (P less than 0.02) and urinary 6-keto-PGF1 alpha (P less than 0.02) than the other patients, but there were no significant differences in the basal excretion rates of PGE2 nor TXB2 among the groups. The therapeutic requirement for spironolactone treatment in patients from Group I was delayed as compared with the other two groups (P less than 0.001) due to the fact that their spontaneous weight loss took place over a long period. For all patients, spironolactone administration produced a significant increase in 6-keto-PGF1 alpha excretion (P less than 0.01) without affecting significantly urinary elimination of PGE2 nor TXB2. A close relationship was found between the spironolactone-induced increments in urinary sodium and urinary 6-keto-PGF1 alpha excretion (r = 0.74, P less than 0.001). It is suggested that the ability of the kidney to synthetize prostacyclin can influence the natriuretic response to spironolactone therapy in patients with liver cirrhosis.

Inhibition of renal prostaglandin synthesis in man: methodological and clinical implications

Integrity of renal prostaglandin synthesis is necessary to maintain renal cortical and medullary function in patients with kidney, heart and liver disease. A comparison of the biochemical effects of various non-steroidal anti-inflammatory drugs (NSAIDs) necessitates that renal prostaglandin synthesis, as reflected by urinary immunoreactive prostaglandin excretion, be assessed with proper attention to problems created by seminal fluid contamination, inadequate chromatographic separation of samples, and largely unknown cross reactivities of systemic eicosanoid metabolites with antibodies raised against primary prostaglandins. Most, but not all, clinical studies support the observation that conventional doses of sulindac, administered orally, do not inhibit renal prostaglandin synthesis or alter renal function. Caution is in order, however, about the use of any NSAID, including sulindac at conventional dosage, in patients with severe liver disease as the plasma levels of sulindac sulfide are increased and prolonged compared to patients with normal hepatic function. Furosemide-induced natriuresis is probably not prostaglandin-mediated, in contrast to increased in renal blood flow and renin release. Some NSAIDs can attenuate the efficacy of antihypertensive therapy. Inasmuch as sulindac does inhibit systemic vascular prostacyclin production, its lack of hypertensive effect vis-a-vis other NSAIDs argues in favor of the importance of intrarenal prostaglandin-dependent mechanisms in mediating the hemodynamic effects of non-selective cyclooxygenase inhibitors.