endothelin-1 and Endotoxemia

Topics: Acute Kidney Injury; Animals; Biomarkers; Contrast Media; Endothelin Receptor Antagonists; Endothelin-1; Endotoxemia; Erythropoietin; Fibrosis; Glycopeptides; Heart Failure; Humans; Hypotension; Kidney Failure, Chronic; Peptides, Cyclic; Peritoneal Dialysis; Peritoneum; Prognosis; Recombinant Proteins; Renal Dialysis

There is a growing body of evidence from clinical and epidemiologic studies that in utero exposure to infection plays an important role in the genesis of fetal or neonatal injury leading to cerebral palsy and chronic lung disease. Thus, after chorioamnionitis the incidence of immature neonates with periventricular white matter damage and periventricular or intraventricular hemorrhage is significantly elevated. Recent clinical and experimental data support the hypothesis that a fetal inflammatory response links antenatal infection with brain white matter damage and subsequent motor handicap. A variety of studies support the view that cytokines released during intrauterine infection directly cause injury to the immature brain. In this review, we provide evidence that in utero exposure to bacterial infection can severely alter fetal cardiovascular function, resulting in dysregulation of cerebral blood flow and subsequent hypoxic-ischemic brain injury.

Topics: Animals; Cardiovascular System; Cerebral Hemorrhage; Cerebral Palsy; Cytokines; Endothelin-1; Endotoxemia; Endotoxins; Female; Fetal Diseases; Humans; Hypoxia-Ischemia, Brain; Infant, Newborn; Infant, Newborn, Diseases; Nitric Oxide; Pregnancy; Pregnancy Complications, Infectious

Endotoxin is a major stimulus for triggering the host response in septicaemia. The pathophysiology of sepsis involves activation of the vascular endothelium and leukocytes, resulting in the release of various mediators, e.g. cytokines, nitric oxide (NO), endothelin (ET-1) and complement factors. We evaluated the blood levels of complement activation, ET-1 and neuropeptide Y (NPY) in parallel with the haemodynamic and oxygen transport response during human experimental endotoxemia.. Eleven healthy men had venous, arterial and pulmonary arterial catheters placed for continuous haemodynamic measuring. After 30 min rest endotoxin (E. Coli 4 ng kg(-1), Lot G1) was intravenously administered. Blood samples from pulmonary and arterial catheters were collected hourly over 4 h.. Body temperature augmented significantly from baseline values (36.7 +/- 0.7 degrees C, mean +/- SEM) with a maximum after 3.5 h (39.1 +/- 0.3 degrees C, P < 0.001). Cardiac output increased by 100%, systemic vascular resistance decreased by 50%, the oxygen consumption and the tissue oxygen transport increased. Activation of the complement system was indicated by an increase in SC5b-9. Endothelin-1-like immunoreactivity (ET-1-LI) increased over time in arterial blood. NPY-like immunoreactivity (NPY-LI) did not change over time.. A dose of endotoxin associated with reproducible systemic vasodilation and fever in healthy subjects causes complement activation and increased systemic levels of ET-1-LI, illustrating that the model is a useful tool for inducing moderate systemic inflammation where several mediator systems are activated.

Topics: Adult; Body Temperature; Complement Activation; Endothelin-1; Endotoxemia; Endotoxins; Hemodynamics; Humans; Inflammation; Male; Neuropeptide Y; Oxygen Consumption; Pulmonary Alveoli; Pulmonary Gas Exchange

In the present study, we hypothesized that endotoxemia produces metalloendopeptidase (MEPD)-dependent generation of endothelin-1 (ET-1) and alters NOS expression correlating with p38-mitogen-activated protein kinase (MAPK) phosphorylation in thoracic aorta. Male Sprague-Dawley rats (350-400 g) were subjected to two groups randomly; sham-treated (N = 10) and lipopolysaccharide (LPS)-treated (N = 10) (E. coli LPS 2 mg/kg bolus + 2 mg/kg infusion for 30 min). The animals in each group were further subdivided into vehicle and MEPD inhibitor phosphoramidon (1 mg/kg bolus, PHOS)-treated groups. LPS produces a significant decrease in mean arterial pressure (MAP) at 2 h post endotoxemia that was blocked by PHOS. PHOS attenuated LPS-induced increase in tumor necrosis factor-alpha (TNF-alpha) concentration at 2- and 24 h post-LPS administration. LPS significantly elevated plasma concentrations of ET-1 at 2- and 24 h post endotoxemia. An upregulated preproET-1 expression following both LPS and MEPD inhibition was observed in thoracic aorta at 2 h post treatment. PHOS effectively blocked conversion of preproET-1 to ET-1 in thoracic aorta locally at 24 h post treatment in endotoxic rats. PHOS inhibited LPS-induced upregulation of inducible NOS (iNOS), downregulation of endothelial NOS (eNOS) and elevation of NO byproducts (NOx) in thoracic aorta. PHOS also blocked LPS-induced upregulated p38-MAPK phosphorylation in thoracic aorta at 24 h post endotoxemia. The data revealed that LPS induces MEPD-sensitive inflammatory response syndrome (SIRS) at 2- and 24 h post endotoxemia. We concluded that inhibition of MEPD not only decreases the levels of ET-1 but also simultaneously downregulates protein expression of iNOS and phosphorylated p38-MAPK while increasing eNOS in thoracic aorta during SIRS in endotoxemia. We suggest that MEPD-dependent ET-1 and NO mechanisms may be involved in endotoxemia-induced altered p38-MAPK phosphorylation.

Topics: Animals; Aorta, Thoracic; Blood Pressure; Cytokines; Endothelin-1; Endotoxemia; Glycopeptides; Immunoblotting; Lipopolysaccharides; Male; Metalloendopeptidases; Models, Biological; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Rats; Rats, Sprague-Dawley; Time Factors; Up-Regulation

Endothelial dysfunction and oxidative stress were hypothesized to be involved in the pathogenesis of coronary microvascular angina (MVA). NADPH oxidase-2 (NOX2) activation could provoke increased oxidative stress and endothelial dysfunction, but data on MVA have not been provided yet.. This study aimed to evaluate the interaction among NOX2 activation, serum lipopolysaccharide (LPS) levels, as well as oxidative stress production as potential causes of endothelial dysfunction in MVA patients.. In this study, we wanted to compare serum levels of soluble NOX2-dp (sNOX2-dp), H2O2 production, hydrogen peroxide breakdown activity (HBA), nitric oxide (NO) bioavailability, endothelin 1 (ET-1), serum zonulin (as intestinal permeability assay), and LPS in 80 consecutive subjects, including 40 MVA patients and 40 controls (CT), matched for age and sex.. Compared with CT, MVA patients had significantly higher values of sNOX2-dp, H2O2, ET-1, LPS, and zonulin. Conversely HBA and NO bioavailability were significantly lower in MVA patients. Simple linear regression analysis showed that sNOX2 was associated with serum LPS, serum zonulin, H2O2, and ET-1. Furthermore, an inverse correlation between sNOX2, HBA, and nitric oxide bioavailability was observed. Multiple linear regression analysis showed that LPS and zonulin emerged as the only independent predictive variables associated with sNOX2.. This study provides the first report attesting that patients with MVA have high LPS levels, NOX2 activation, and an imbalance between pro-oxidant and antioxidant systems, in favor of the oxidizing molecules that could be potentially implicated in the endothelial dysfunction and vasoconstriction of this disease.

Topics: Antioxidants; Endothelin-1; Endotoxemia; Humans; Hydrogen Peroxide; Lipopolysaccharides; Microvascular Angina; NADPH Oxidase 2; Nitric Oxide; Oxidative Stress; Reactive Oxygen Species

Hepatorenal syndrome (HRS), a severe complication of advanced cirrhosis, is defined as hypoperfusion of kidneys resulting from intense renal vasoconstriction in response to generalized systemic arterial vasodilatation. Nevertheless, the mechanisms have been barely investigated. Cumulative studies demonstrated renal vasodilatation in portal hypertensive and compensated cirrhotic rats. Previously, we identified that blunted renal vascular reactivity of portal hypertensive rats was reversed after lipopolysaccharide (LPS). This study was therefore conducted to delineate the sequence of renal vascular alternation and underlying mechanisms in LPS-treated cirrhotic rats. Sprague-Dawley rats were randomly allocated to receive sham surgery (Sham) or common bile duct ligation (CBDL). LPS was induced on the 28th day after surgery. Kidney perfusion was performed at 0.5 or 3 h after LPS to evaluate renal vascular response to endothelin-1 (ET-1). Endotoxemia increased serum ET-1 levels ( P < 0.0001) and renal arterial blood flow ( P < 0.05) in both Sham and CBDL rats. CBDL rats showed enhanced renal vascular reactivity to ET-1 at 3 h after LPS ( P = 0.026). Pretreatment with endothelin receptor type A (ET

Topics: Animals; Endothelin A Receptor Antagonists; Endothelin-1; Endotoxemia; Hepatorenal Syndrome; Lipopolysaccharides; Male; MAP Kinase Signaling System; Nitric Oxide Synthase Type II; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Renal Circulation; Vasodilation

Effective management of hypotension refractory to vasoconstrictors in severe sepsis is limited. A new strategy to ameliorate endotoxemic hypotension by inducing endothelium-dependent constriction of large arteries was assessed.. Endotoxemia in rats was induced by injection of LPS (10 mg·kg(-1), i.v.). Haemodynamics were measured in vivo, reactivity of isolated mesenteric arteries by myography and expression of proteins and enzyme activities by immunohistochemistry, biochemistry and molecular biology.. Six hours after LPS, the hypotension was promptly reversed following injection (i.v. or i.p.) of oroxylin-A (OroA) . In isolated LPS-treated but not normal mesenteric arteries, OroA (1-10 μM) induced endothelium-dependent, sustained constriction, blocked by endothelin-1 (ET-1) receptor antagonists. OroA further enhanced LPS-induced expression of endothelin-converting enzyme, ET-1 mRNA and proteins and ET-1 release, OroA also enhanced phosphorylation of Rho-associated protein kinase (ROCK) and reversed LPS-induced suppression of RhoA activities in smooth muscle of arteries with endothelium. Activated- phosphorylation of smooth muscle ROCK was blocked by ET-1-receptor antagonists and ROCK inhibitors. Moreover, OroA post-treatment suppressed, via inhibiting NF-κB activation, inducible NOS expression and circulating NO.. Reversal of endotoxemic hypotensive by OroA was due to release of endothelial ET-1, upregulated by LPS, from mesenteric arteries, inducing prompt and sustained vasoconstriction via activation of vascular smooth muscle RhoA/ROCK-pathway. In late endotoxemia, OroA-induced vasoconstriction was partly due to decreased circulating NO. Activation of endothelium-dependent constriction in large resistance arteries and suppression of systemic inflammation offer new strategies for acute management of endotoxemic hypotensive shock.

Topics: Animals; Endothelin A Receptor Antagonists; Endothelin-1; Endothelium, Vascular; Endotoxemia; Flavonoids; Hypotension; Lipopolysaccharides; Male; Mesenteric Arteries; Nitric Oxide; Nitric Oxide Synthase Type II; Phosphorylation; Rats, Sprague-Dawley; rho-Associated Kinases; rhoA GTP-Binding Protein; Shock, Septic; Vasoconstriction

Elevated serum concentrations of the vasoactive protein endothelin-1 (ET-1) occur in the setting of systemic inflammatory response syndrome and contribute to distal organ hypoperfusion and pulmonary hypertension. Thus, understanding the cellular source and transcriptional regulation of systemic inflammatory stress-induced ET-1 expression may reveal therapeutic targets. Using a murine model of LPS-induced septic shock, we demonstrate that the hepatic macrophage is the primary source of elevated circulating ET-1, rather than the endothelium as previously proposed. Using pharmacologic inhibitors, ET-1 promoter luciferase assays, and by silencing and overexpressing NF-κB inhibitory protein IκB expression, we demonstrate that LPS-induced ET-1 expression occurs via an NF-κB-dependent pathway. Finally, the specific role of the cRel/p65 inhibitory protein IκBβ was evaluated. Although cytoplasmic IκBβ inhibits activity of cRel-containing NF-κB dimers, nuclear IκBβ stabilizes NF-κB/DNA binding and enhances gene expression. Using targeted pharmacologic therapies to specifically prevent IκBβ/NF-κB signaling, as well as mice genetically modified to overexpress IκBβ, we show that nuclear IκBβ is both necessary and sufficient to drive LPS-induced ET-1 expression. Together, these results mechanistically link the innate immune response mediated by IκBβ/NF-κB to ET-1 expression and potentially reveal therapeutic targets for patients with Gram-negative septic shock.

Topics: Animals; Cell Line; Endothelin-1; Endotoxemia; Gene Expression Regulation; I-kappa B Proteins; Liver; Macrophages; Male; Mice; Mice, Inbred ICR; Mice, Transgenic; NF-kappa B; Signal Transduction

Sepsis is a cluster of heterogeneous syndromes associated with progressive endotoxemic developments, ultimately leading to damage of multiple organs, including the heart. However, the pathogenesis of sepsis-induced myocardial dysfunction is still not fully understood. The present study is the first to examine alterations in expression of key angiogenic signaling system mediated by vascular endothelial growth factor (VEGF) in septic heart and the effects of endothelin dual blocker (ETDB) on it.. Normal Wistar rats were either administered with: a) vehicle only (control group), b) lipopolysaccharide only (LPS: 15 mg/kg) and then sacrificed at different time points (1 h, 3 h, 6 h and 10 h), and c) the last group was co-administered with LPS and ETDB (SB-209670, 1 mg/kg body weight) for 6 h and then sacrificed.. Administration of LPS resulted in increases in levels of: a) serum tumor necrosis factor (TNF)-α, b) serum VEGF and c) serum endothelin (ET)-1 levels accompanied by up-regulation of cardiac VEGF and its downstream angiogenic signaling molecules. While cardiac TNF-α level was unchanged among experimental groups, cardiac ET-1 level was significantly higher in LPS-administered group.. We conclude that elevation in VEGF angiogenic signaling may be triggered by diminished oxygenation in the myocardium following LPS administration as a consequence of sepsis-induced microvascular dysfunction. Because of this cardiac dysfunction, oxygen supply may be inadequate at microregional level to support the normal heart metabolism and function. ETDB at 6 h further increased the elevated levels of VEGF angiogenic signaling in endotoxemic heart.

Topics: Animals; Blood Gas Analysis; Disease Models, Animal; Endothelin Receptor Antagonists; Endothelin-1; Endotoxemia; Hemodynamics; Lipopolysaccharides; Male; Myocardium; Neovascularization, Physiologic; Nitric Oxide; Nitric Oxide Synthase Type III; Rats, Wistar; Signal Transduction; Tumor Necrosis Factor-alpha; Up-Regulation; Vascular Endothelial Growth Factor A

Vascular leakage and oedema formation are key components in sepsis. In septic patients, plasma levels of the vasoconstrictive and pro-inflammatory peptide endothelin-1 (ET-1) correlate with mortality. During sepsis, neutrophils release heparin-binding protein (HBP) known to increase vascular permeability and to be a promising biomarker of human sepsis. As disruption of ET-signalling in endotoxemia attenuates formation of oedema, we hypothesized that this effect could be related to decreased levels of HBP. To investigate this, we studied the effects of ET-receptor antagonism on plasma HBP and oedema formation in a porcine model of sepsis. In addition, to further characterize a potential endothelin/HBP interaction, we investigated the effects of graded ET-receptor agonist infusions.. Sixteen anesthetized pigs were subjected to 5 h of endotoxemia and were randomized to receive either the ET-receptor antagonist tezosentan or vehicle after 2 h. Haemodynamics, gas-exchange and lung water were monitored. In separate experiments, plasma HBP was measured in eight non-endotoxemic animals exposed to graded infusion of ET-1 or sarafotoxin 6c.. Endotoxemia increased plasma ET-1, plasma HBP, and extravascular lung water. Tezosentan-treatment markedly attenuated plasma HBP and extravascular lung water, and these parameters correlated significantly. Tezosentan decreased pulmonary vascular resistance and increased respiratory compliance. In non-endotoxemic pigs graded ET-1 and sarafotoxin 6c infusions caused a dose-dependent increase in plasma HBP.. ET-receptor antagonism reduces porcine endotoxin-induced pulmonary oedema and plasma levels of the oedema-promoting protein HBP. Moreover, direct ET-receptor stimulation distinctively increases plasma HBP. Together, these results suggest a novel mechanism by which ET-1 contributes to formation of oedema during experimental sepsis.

Topics: Animals; Antimicrobial Cationic Peptides; Blood Proteins; Capillary Leak Syndrome; Carrier Proteins; Dose-Response Relationship, Drug; Endothelin Receptor Antagonists; Endothelin-1; Endotoxemia; Endotoxins; Extravascular Lung Water; Female; Hemodynamics; Inflammation; Infusions, Intravenous; Leukocyte Count; Male; Neutrophil Activation; Pulmonary Edema; Pyridines; Random Allocation; Receptor, Endothelin B; Sus scrofa; Swine; Tetrazoles; Viper Venoms

Septic shock, the severe form of sepsis, is associated with development of progressive damage in multiple organs. Kidney can be injured and its functions altered by activation of coagulation, vasoactive-peptide and inflammatory processes in sepsis. Endothelin (ET)-1, a potent vasoconstrictor, is implicated in the pathogenesis of sepsis and its complications. Protease-activated receptors (PARs) are shown to play an important role in the interplay between inflammation and coagulation. We examined the time-dependent alterations of ET-1 and inflammatory cytokine, such as tumor necrosis factor (TNF)-α in kidney tissue in lipopolysaccharide (LPS)-induced septic rat model and the effects of PAR2 blocking peptide on the LPS-induced elevations of renal ET-1 and TNF-α levels.. Male Wistar rats at 8 weeks of age were administered with either saline solution or LPS at different time points (1, 3, 6 and 10h). Additionally, we treated LPS-administered rats with PAR2 blocking peptide for 3h to assess whether blockade of PAR2 has a regulatory role on the ET-1 level in septic kidney.. An increase in ET-1 peptide level was observed in kidney tissue after LPS administration time-dependently. Levels of renal TNF-α peaked (around 12-fold) at 1h of sepsis. Interestingly, PAR2 blocking peptide normalized the LPS-induced elevations of renal ET-1 and TNF-α levels.. The present study reveals a distinct chronological expression of ET-1 and TNF-α in LPS-administered renal tissues and that blockade of PAR2 may play a crucial role in treating renal injury, via normalization of inflammation, coagulation and vaso-active peptide.

Topics: Animals; Disease Models, Animal; Endothelin-1; Endotoxemia; Kidney Diseases; Lipopolysaccharides; Male; Peptide Fragments; Rats; Rats, Wistar; Receptor, PAR-2; Treatment Outcome; Tumor Necrosis Factor-alpha

Endothelin (ET)-1 is the best known potent vasoconstrictor and has been implicated in pathogenesis of sepsis-associated acute kidney injury (AKI) in human or lipopolysaccharide (LPS)-induced AKI in animal models. We have previously shown that ET-1 is highly up-regulated in renal tissues and in plasma after LPS administration. Here, we investigated whether landiolol hydrochloride, an ultra-short-acting beta-blocker, can play an important role in ameliorating levels of LPS-induced up-regulation of renal HIF-1α-ET-1 system and inflammatory cytokines in a rat model of endotoxemia.. Male Wistar rats at 8 weeks of age were either administered with: a) lipopolysaccharide (LPS) only for three hours (3 h) or b) LPS, followed by continuous administration of landiolol for 3 h; c) third group was only treated with vehicle.. At 3 h after LPS administration there was: a) minimal injury in kidney tissues; b) circulatory levels of creatinine, blood urea nitrogen and NGAL increased and c) expression of inflammatory cytokines, such as TNF-α, IL-6 and iNOS increased at the level of both circulatory and renal tissues. In addition, LPS significantly induced renal expression of ET-1 and HIF-1α compared to control. Finally, treatment of LPS-administered rats with landiolol for 3 h normalized elevated serum markers of renal injury and up-regulated levels of renal HIF-1α-ET-1 system with normalization of TNF-α.. Taken together, these data led us to conclude that landiolol ameliorates the up-regulation of HIF-1α-ET-1 system in minimally morphologically-injured kidney and normalizes biomarkers of renal injury in early hours of endotoxemia of a rat model.

Topics: Animals; Biomarkers; Blood Gas Analysis; Blood Pressure; Disease Models, Animal; Endothelin-1; Endotoxemia; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Inflammation Mediators; Kidney; Lipopolysaccharides; Male; Morpholines; Rats, Wistar; RNA, Messenger; Up-Regulation; Urea

Despite being protective in many disease states, hydrogen sulfide (H(2)S) contributes to organ injury in sepsis. Like the other gasotransmitters, nitric oxide and carbon monoxide, H(2)S is a modulator of the microcirculation. Because microcirculatory dysfunction is a main cause of organ injury during sepsis, the present study was designed to test the effect of H(2)S on microvascular dysfunction in isolated perfused livers. In most microcirculatory beds, endotoxin activates the endothelium, resulting in hyporesponsiveness to catecholamines and a derangement in blood flow distribution. We demonstrate that H(2)S treatment attenuates the increase in portal pressure during infusion of the α1 adrenergic agonist, phenylephrine (PE) (P < 0.01). Hydrogen sulfide almost completely negated the increase in portal pressure in livers isolated from endotoxemic rats. Treatment with an inhibitor of endogenous H(2)S, DL-propargylglycine (PAG), reversed lipopolysaccharide-induced hyporesponsiveness to PE. Because hepatic microcirculatory dysfunction is associated with excessive sinusoidal vasoconstriction and not dilation, we investigated whether H(2)S affects endothelin 1 (ET-1)-induced vasoconstriction in isolated livers. Contrary to PE treatment, H(2)S did not affect the increase in portal pressure during infusion of ET-1, nor did it attenuate the hypersensitization of the liver to ET-1 during endotoxemia. Hepatic resistance in control rats was increased by PAG treatment during ET-1 infusion, but this increase was not exacerbated during endotoxemia. We monitored hepatic O(2) consumption to assess the effect of vascular changes on oxygen consumption following ET-1 treatment. Low-dose ET-1 infusion caused an increase in hepatic O(2)consumption, whereas low-dose ET-1 infusion decreased O(2) consumption in endotoxemic livers. Interestingly, whereas we observed no effect of PAG on the vascular response to ET-1 infusion during endotoxemia, PAG treatment did maintain O(2), suggesting a more complex effect of H(2)S inhibition. In summary, the discrepancies between the hepatic response to PE and ET-1 suggest that H(2)S differentially contributes to microcirculatory dysfunction in the systemic and hepatic microcirculations. We propose that this is due to H(2)S exerting a differential vasoactive function on presinusoidal and sinusoidal sites within the liver. Moreover, our findings suggest that H(2)S may contribute to the progression of sepsis by contributing to microvascular failu

Topics: Animals; Endothelin-1; Endotoxemia; Hydrogen Sulfide; Lipopolysaccharides; Liver; Male; Microcirculation; Oxygen Consumption; Phenylephrine; Portal Pressure; Random Allocation; Rats; Rats, Sprague-Dawley; Vascular Resistance; Vasoconstrictor Agents; Vasodilator Agents

The potent vasoconstrictor endothelin-1 has been implicated in the pathogenesis of plasma oxidative stress seen in sepsis. The selective endothelin receptor blockers BQ123 and BQ788 were used to investigate the importance of selective endothelin receptor blockage in modulating oxidative stress during endotoxemia.. The study was performed on male Wistar rats (n = 6 per group) divided into groups: (1) saline, (2) lipopolysaccharide (LPS) (15 mg/kg)-saline, (3) BQ123 (0.5 mg/kg)-LPS, (4) BQ123 (1 mg/kg)-LPS, (5) BQ788 (3 mg/kg)-LPS. The endothelin receptor type A(ETA-R) or type B (ETB-R) antagonist was injected intravenously 30 min before LPS administration. Blood pressure was monitored and blood was taken before, 90 min and 300 min after saline or LPS administration.. Injection of LPS alone resulted in a decrease in mean arterial pressure (MAP) (p < 0.05), a decrease in ferric reducing ability of plasma (FRAP) value (p < 0.01) and a marked increase in plasma tumor necrosis factor α (TNF-α) and thiobarbituric acid reactive substances (TBARS) (p < 0.001, p < 0.001, respectively). Administration of BQ123 before LPS administration deteriorated MAP in a dose dependent way. Moreover, BQ123 (1 mg/kg) decreased plasma level of TBARS and TNF-α (p < 0.01 and p < 0.05, respectively) and increased FRAP value (p < 0.001). On the contrary, BQ788 prevented LPS-induced decrease in MAP(p < 0.001) and led to a significant reduction in plasma TBARS concentration (p < 0.01).. Our study showed that blockage of ETB-R during endotoxemia improved blood hemodynamics and decreased plasma lipid peroxidation. Blockage of ETA-R improved plasma antioxidant status and decreased lipid peroxidation and TNF-α production, but it deteriorated hemodynamic conditions.

Topics: Animals; Antioxidants; Arterial Pressure; Disease Models, Animal; Drug Administration Schedule; Endothelin A Receptor Antagonists; Endothelin B Receptor Antagonists; Endothelin-1; Endotoxemia; Hemodynamics; Injections, Intravenous; Lipid Peroxidation; Lipopolysaccharides; Male; Oligopeptides; Oxidative Stress; Peptides, Cyclic; Piperidines; Rats; Rats, Inbred WKY; Receptor, Endothelin A; Receptor, Endothelin B; Thiobarbituric Acid Reactive Substances; Time Factors; Tumor Necrosis Factor-alpha; Vasoconstrictor Agents

The objective of this study was to evaluate the effect of oral supplementation with a combination of arginine and glutamine on the intestinal mucosa and inflammatory cytokines of lipopolysaccharide (LPS)-induced adult rats. Fifty Sprague-Dawley rats (average weight of 185 ± 15 g) were randomly divided into five groups: control group A (CA) and control group B (CB), both orally supplemented with 0.9% saline; group Arg, supplemented with 300 mg/kg day(-1) arginine; group Gln, supplemented with 300 mg/kg day(-1) glutamine; group AG, supplemented with 150 mg/kg day(-1) arginine and 150 mg/kg day(-1) glutamine. The experiment lasted for 2 weeks. Food intake and body weight were measured during the experiment. At 10.00 h of day 15, animals were injected with 4 mg/kg LPS (group CB, Arg, Gln, and AG) or sterile saline (group CA) after supplementation. Then at 14.00 h, all animals were killed and blood and tissue collected. The results showed that compared with group CB, arginine concentration tended to be increased (P > 0.05) in group Arg and AG, while there was no significant difference in glutamine concentration among the groups challenged with LPS. Oral supplementation with arginine or/and glutamine mitigated morphology impairment (lower villus height, P < 0.05) in the jejunum and ileum induced by LPS challenge. LPS administration resulted in a significant increase in TNF-α, IL-1β, IL-6 and IL-10 mRNA abundance. Arginine only significantly decreased TNF-α mRNA abundance in the ileum, while glutamine significantly decreased both TNF-α and IL-10 mRNA in the ileum. A combination of arginine and glutamine significantly decreased TNF-α and IL-1β mRNA abundance in both the jejunum and ileum, while they also significantly decreased anti-inflammatory IL-10 in the ileum. These results revealed that an oral supply of combined arginine and glutamine had more favorable effects on the intestinal mucosa and inflammatory cytokines than a supply of arginine or glutamine alone.

Topics: Administration, Oral; Amine Oxidase (Copper-Containing); Animals; Arginine; Cytokines; Endothelin-1; Endotoxemia; Gene Expression; Glutamine; Ileum; Intestinal Mucosa; Jejunum; Lipopolysaccharides; Male; Microvilli; Rats; Rats, Sprague-Dawley

Endothelin (ET)-1 is a potent vasoconstrictor that has been implicated in the pathogenesis of a number of diseases, and some studies suggest that circulating ET-1 is elevated in sepsis. The present study investigated whether ET plays a role in sepsis-mediated acute lung injury and whether its expression could be down regulated by blockade of TNF-α in septic lung. Male Wistar rats at 8 weeks of age were administered with either saline or lipopolysaccharide (LPS) at different time points (1, 3, 6 and 10 h) and various tests were then performed. The features of acute lung injury were observed at 1 h after LPS administration, which gradually became severe with time. Systolic and diastolic pressures were reduced just about one hour after LPS administration, whereas pulmonary TNF-α levels were significantly increased at various time points after LPS administration. LPS induced a time-dependent expression of ET-1 and ET(A) receptor in the lungs compared to control, peaking and increasing by 3 fold at 6 h after induction of endotoxemia, whereas levels of ET(B) receptor, which has vasodilating effects, were remarkably down regulated time-dependently. We conclude that time-dependent increase of ET-1 and ET(A) receptor with the down regulation of ET(B) receptor may play a role in the pathogenesis of acute lung injury in endotoxemia. Finally, treatment of LPS-administered rats with TNF-α blocking peptide for three hours significantly suppressed levels of pulmonary ET-1. These data taken together, led us to conclude that differential alteration in ET expression and its receptors may be mediated by TNF-α and may, in part, account for the pathogenesis of acute lung injury in endotoxemia.

Topics: Acute Lung Injury; Animals; Blood Gas Analysis; Blood Pressure; Endothelin-1; Endotoxemia; Lactic Acid; Lipopolysaccharides; Lung; Male; Organ Size; Peptides; Rats; Rats, Wistar; Receptors, Endothelin; Tumor Necrosis Factor-alpha

Inhalation of nitric oxide (INO) has distant effects. By a blood- borne factor, INO down-regulates endogenous nitric oxide production in healthy pig lungs, resulting in vasoconstriction in lung regions not directly reached by INO. The aim of this study was to investigate whether INO has distant effects in endotoxemic pig lungs. The hypothesis was that INO down-regulates endogenous NO production in lung regions not reached by INO.. Prospective, randomized animal study.. University hospital research laboratory.. Twenty-two pairs of domestic pigs.. Cross-circulation was established in 22 pairs of anesthetized pigs. Nine pairs received endotoxin (control group) and 13 pairs received endotoxin, with one pig inhaling NO (80 ppm) and one pig receiving blood from that pig (NO-blood recipient group).. NO in exhaled air, NO synthase activity in lung tissue, endothelin-1 in the blood, ETA and ETB receptor immunoreactivity in lung tissue, vital parameters, and blood gases were measured. Endotoxin per se increased NO in exhaled air by 100% compared to baseline (control group). In the NO-blood recipient group, i.e., pigs receiving blood from the NO-inhaling pigs, NO in exhaled air increased by 300% (p = .03). The Ca-dependent NO synthase activity was higher in these pigs (p = .02), indicating increased endogenous NO production. The ET B receptor immunoreactivity was higher in the NO-blood recipient group (p = .004).. As opposed to findings in healthy pigs, INO in endotoxemic pigs causes an increase in endogenous NO production in lung regions not reached by INO. Increased NO production in nonventilated lung regions may cause vasodilatation, counteracting the INO-induced increase in blood flow to the ventilated lung regions.

Topics: Administration, Inhalation; Analysis of Variance; Animals; Blood Gas Analysis; Disease Models, Animal; Endothelin-1; Endotoxemia; Endotoxins; Escherichia coli; Hemodynamics; Nitric Oxide; Probability; Pulmonary Circulation; Radioimmunoassay; Random Allocation; Reference Values; Survival Rate; Sus scrofa; Swine

Severe sepsis involves a complex response including the activation of lots of cells, inflammatory mediators, and the hemostatic system. Central to this process is an alteration of endothelial cell function. Therefore, we investigated whether an endothelial bioreactor (EBR) would provide a new therapeutic approach to this clinical disorder.. EBR was constructed using a cartridge which contained with nonwoven polytetrafluoroethylene seeded with porcine iliac artery endothelial cell (PIEC). Pigs were intravenously administered with 0.25 mg/kg lipopolysaccharide and immediately placed in an extracorporeal circuit with EBR or sham controls.. Compared with the sham group, EBR therapy resulted in significantly higher mean arterial blood pressure and significantly lower plasma von Willebrand factor, endothelin-1 and scores of lung injury. These alterations were associated with a significant survival advantage in the EBR group.. Timely intervention with EC therapy in a tissue-engineered bioreactor may improve cardiovascular performance and alter the natural history of endotoxemia sepsis.

Topics: Animals; Bioreactors; Blood Pressure; Endothelial Cells; Endothelin-1; Endotoxemia; Lung; Sepsis; Swine; Tissue Engineering; von Willebrand Factor

The potent vasoconstrictor endothelin-1 has been implicated in the pathogenesis of the microcirculatory dysfunction seen in sepsis. The mixed endothelin receptor antagonist tezosentan and the selective endothelin A-receptor antagonist TBC3711 were used to investigate the importance of the different endothelin receptors in modulating splanchnic regional blood flow and microvascular blood flow in endotoxaemia.. Eighteen anaesthetized pigs were i.v. infused with endotoxin (Escherichia coli lipopolysaccharide, serotype 0111:b4) for 300 min. After 120 min, six animals received tezosentan and six animals received TBC3711. Six animals served as endotoxin-treated controls. Laser Doppler flowmetry was used to measure microcirculatory blood flow in the liver and ileum. Superior mesenteric artery flow (SMA(FI)) and portal vein flow (PV(FI)) were measured with ultrasonic flow probes, and air tonometry was used to measure Pco₂ in the ileal mucosa.. TBC3711 did not improve splanchnic regional blood flow or splanchnic microvascular blood flow compared with endotoxin-treated controls. Tezosentan increased PV(FI) (P<0.05), but SMA(FI) was not improved compared with the other groups. In the tezosentan group, microvascular blood flow in the ileal mucosa (MCQ(muc)) improved and mucosal-arterial Pco₂ gap decreased (P<0.05 for both) compared with endotoxin-treated controls and the TBC3711 group.. Tezosentan improved MCQ(muc) without any concomitant increase in SMA(FI), implying a direct positive effect on the microcirculation. TBC3711 was not effective in improving regional splanchnic blood flow or splanchnic microvascular blood flow. Dual endothelin receptor antagonism was necessary to improve MCQ(muc), indicating a role for the endothelin B-receptor in mediating the microcirculatory failure in the ileal mucosa.

Topics: Animals; Endothelin A Receptor Antagonists; Endothelin B Receptor Antagonists; Endothelin-1; Endotoxemia; Female; Hypertension, Pulmonary; Ileum; Intestinal Mucosa; Isoxazoles; Microcirculation; Pyridines; Receptor, Endothelin A; Receptor, Endothelin B; Splanchnic Circulation; Sulfones; Sus scrofa; Tetrazoles; Vasodilator Agents

Cirrhotic patients with portal hypertension and variceal hemorrhage are vulnerable to endotoxemia. However, the direct influence of endotoxemia on portal-systemic collateral vasculature remains unexplored. In this study, portal hypertension was induced in Sprague-Dawley rats by partial portal vein ligation. On the 7th day after portal vein ligation, at 0.5, 1.5, and 5 h post endotoxin (LPS; Escherichia coli serotype O111:B4, 3 mg/kg, i.p., E0.5, E1.5 and E5, respectively) or saline (control, C0.5, C1.5, and C5, respectively) injection, hemodynamic measurements and concentration-response relationships to arginine vasopressin (AVP; 10(-10)-10(-7) mol/L) in collateral vascular bed were obtained. In another six parallel groups, reverse-transcriptase-polymerase chain reaction of iNOS, eNOS, and endothelin 1 (ET-1) mRNA expressions for splenorenal shunt, the most prominent intra-abdominal collateral vessel, was performed. The results showed that E0.5 had lower perfusion pressure changes to AVP and higher splenorenal shunt eNOS expression than C0.5 group (P < 0.05). Compared with C1.5, tachycardia, higher perfusion pressure changes and enhanced splenorenal shunt iNOS and ET-1 expression were observed in E1.5 group (P < 0.05). In E5, systemic and portal hypotension with markedly enhanced collateral AVP responsiveness and splenorenal shunt iNOS and ET-1 expressions were noted (P < 0.05). In conclusion, vasoactive substances counterregulation participates, at least in part, the time-dependent changes of collateral AVP responsiveness in endotoxemic portal hypertensive rats.

Topics: Animals; Arginine Vasopressin; Endothelin-1; Endotoxemia; Hemodynamics; Hypertension, Portal; Lipopolysaccharides; Male; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; Vasoconstrictor Agents

Acute kidney injury (AKI) in septic patients drastically increases the mortality to 50-80%. Sepsis is characterized by hemodynamic perturbations as well as overwhelming induction of proinflammatory cytokines. Since ghrelin has been shown to have anti-inflammatory properties, we hypothesized that ghrelin may afford renal protection during endotoxemia-induced AKI. Studies were conducted in a normotensive endotoxemia-induced AKI model in mice by intraperitoneal injection of 3.5 mg/kg LPS. Serum ghrelin levels were increased during endotoxemia accompanied by increased ghrelin receptor (GHSR-1a) protein expression in the kidney. Ghrelin administration (1.0 mg/kg sc 6 h and 30 min before and 14 h after LPS) significantly decreased serum cytokine levels (TNF-alpha, IL-1beta, and IL-6) and serum endothelin-1 levels which had been induced by LPS. The elevated serum nitric oxide (NO) levels and renal inducible NO synthase expression were also decreased by ghrelin. Renal TNF-alpha levels were also increased significantly in response to LPS and ghrelin significantly attenuated this increase. When administrated before LPS, ghrelin protected against the fall in glomerular filtration rate at 16 h (172.9 +/- 14.7 vs. 90.6 +/- 15.2 microl/min, P < 0.001) and 24 h (147.2 +/- 20.3 vs. 59.4 +/- 20.7 microl/min, P < 0.05) as well as renal blood flow at 16 h (1.65 +/- 0.07 vs. 1.47 +/- 0.04 ml/min, P < 0.01) and 24 h (1.56 +/- 0.08 vs. 1.22 +/- 0.03 ml/min, P < 0.05) after LPS administration without affecting mean arterial pressure. Ghrelin remained renal protective even when it was given after LPS. In summary, ghrelin offered significant protection against endotoxemia-induced AKI. The renal protective effect of ghrelin was associated with an inhibition of the proinflammatory cytokines. Of particular importance was the suppression of TNF-alpha both in the circulation and kidney tissues. Thus, ghrelin may be a promising peptide in managing endotoxemia-induced AKI.

Topics: Acute Kidney Injury; Animals; Body Weight; Cyclic GMP; Endothelin-1; Endotoxemia; Escherichia coli Infections; Ghrelin; HMGB1 Protein; Kidney; Kidney Function Tests; Lipopolysaccharides; Male; Mice; Mice, Inbred C57BL; Nitric Oxide; Nitric Oxide Synthase Type II; Receptors, Ghrelin; Tumor Necrosis Factor-alpha

Myocardial depression in sepsis is frequently encountered clinically and contributes to morbidity and mortality. Increased plasma levels of endothelin-1 (ET-1) have been described in septic shock, and previous reports have shown beneficial effects on cardiovascular performance and survival in septic models using ET receptor antagonists. The aim of the current study was to investigate specific cardiac effects of ET receptor antagonism in endotoxicosis. Sixteen domestic pigs were anesthetized and subjected to endotoxin for 5 h. Eight of these pigs were given tezosentan (dual ET receptor antagonist) after 3 h. Cardiac effects were evaluated using the left ventricular (LV) pressure-volume relationship. Endotoxin was not associated with any effects on parameters of LV contractile function [end-systolic elastance (Ees), preload recruitable stroke work (PRSW), power(max)/end-diastolic volume (PWR(max)/EDV) and dP/dt(max)/end-diastolic volume (dP/dt(max)/EDV)] but with impairments in isovolumic relaxation (time constant for pressure decay, tau) and mechanical efficiency. Tezosentan administration decreased Ees, PWR(max)/EDV, and dP/dt(max)/EDV, while improving tau and LV stiffness. Thus, dual ET receptor antagonism was associated with a decline in contractile function but, in contrast, improved diastolic function. Positive hemodynamic effects from ET receptor antagonism in acute endotoxemia may be due to changes in cardiac load and enhanced diastolic function rather than improved contractile function.

Topics: Animals; Blood Pressure; Cardiovascular Agents; Coronary Circulation; Disease Models, Animal; Endothelin A Receptor Antagonists; Endothelin B Receptor Antagonists; Endothelin-1; Endotoxemia; Endotoxins; Female; Heart Rate; Myocardial Contraction; Oxygen Consumption; Pyridines; Receptor, Endothelin A; Receptor, Endothelin B; Sus scrofa; Tetrazoles; Time Factors; Ventricular Function, Left; Ventricular Pressure

To elucidate roles of microvascular factors in the pathogenesis of renal complications during endotoxemia, that is characterized by renal vasoconstriction and systemic hypotension/generalized non-renal vasodilation, we profile the expression pattern and time-course of three key vaso-regulators, namely endothelin (ET)-1, nitric oxide (NO), and angiotensin II (Ang II). We hypothesize that disruption of the overall balance between vasodilatation and vasoconstriction in the kidney, during the early phase of sepsis, contribute to its (kidney) predisposition to acute renal failure. Adult male Wistar rats were rendered endotoxemic at different time points (1, 3, 6 and 10 h) by a single i.p. injection of lipopolysaccharide (LPS) (15 mg/kg) dissolved in saline. Control group was injected vehicle only (saline). Both systolic and diastolic blood pressures significantly decreased at different time points after LPS administration. Surprisingly, renal histopathological evaluation showed no remarkable changes in LPS-induced endotoxemia. However, overall, levels of the vaso-regulators and, where applicable, their respective receptors were upregulated: (1) plasma ET-1 increased 25-fold and peaked, as renal ET-1 mRNA, at 3 h; renal ET-1 protein and its receptors, ET type A (ET(A)) receptor (vasoconstrictive) and ET type B (ET(B)) receptor (vasodilatatory) increased in a time-dependent fashion, (2) Ang II increased by 53% compared to control, peaking at 6 h. However, while levels of Ang II type 1 (AT1) receptor increased over time after LPS injection, those of Ang II type 2 (AT2) receptor were downregulated, (3) data of NO system (NO-NOS), the key vasodilator, were the most intriguing. Whereas levels of renal NO increased time-dependently following LPS administration, with a 2240-fold increase in renal iNOS expression, levels of eNOS, were almost unchanged. In conclusion, the present study overall reveals intriguing and complex dynamics between levels of vasoconstrictors and vasodilators during the early phase of LPS-induced endotoxemia. These shifts in molecular expressions are likely triggered by compensatory mechanisms aimed at counteracting the undesirable and dominant effects of one group of vaso-regulatory moiety over the other.

Topics: Angiotensin II; Animals; Blood Pressure; Endothelin-1; Endotoxemia; Kidney; Lipopolysaccharides; Male; Nitric Oxide; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Peptidyl-Dipeptidase A; Rats; Rats, Wistar; Receptor, Angiotensin, Type 2; Receptors, Endothelin; Renal Circulation; RNA, Messenger; Time Factors; Tumor Necrosis Factor-alpha

During severe sepsis, several immunological defense mechanisms initiate a cascade of inflammatory events leading to multiorgan failure, including septic encephalopathy and ultimately death. Endothelin-1 (ET-1) has recently been investigated in different cerebral pathologies. Some reports suggest the involvement of ET-1 in sepsis. However, no study to date has reported the alterations in expression of the genes encoding preproET-1 and ET receptors in the frontal cortex of the septic brain. Male Sprague-Dawley (SD) rats 8 weeks of age were administered either saline or 15 mg/kg lipopolysaccharide (LPS) at different time points (1, 3, 6, and 10 hrs). Rats that did not receive LPS were considered to be controls. The rats were sacrificed with ether, and the brain tissues were harvested. Systolic and diastolic blood pressure decreased 1 hr after LPS administration and then gradually returned to normal, without any change in the heart rate. We confirmed the induction of endotoxemia in the brains of SD rats by measuring the expression of nitric oxide synthase (NOS) mRNA induced in the cerebrum. The expression of inducible NOS (iNOS) mRNA in the brains of SD rat after LPS administration was 30-fold higher than that in the brains of control rats. mRNA expression of preproET-1 in the frontal cortex of SD rats after LPS administration was 2-fold higher than that in control rats. A time-dependent increase in the expression of the gene encoding the ET(A) receptor (vasoconstrictive property) after LPS administration was observed in SD rat brain, whereas expression of the gene encoding the ET(B) receptor (vasodilatatory property) showed an initial upregulation and then gradually decreased as sepsis progressed. In conclusion, we report for the first time that expressions of the genes encoding ET-1 and ET receptors are altered in the endotoxemic brain and that these alterations are time-dependent in SD rats. The alterations in the ET system in brain tissue observed in the present study may contribute to the understanding of the pathophysiological changes in the endotoxemic brain.

Topics: Animals; Brain; Endothelin-1; Endotoxemia; Lipopolysaccharides; Nitric Oxide Synthase Type II; Rats; Receptor, Endothelin A; Receptor, Endothelin B; RNA, Messenger; Time Factors

To evaluate the role of intestinal endotoxemia in the genesis of hepatopulmonary syndrome.. A rat model of cirrhosis was prepared with the method of compound factors. At the end of the eighth week, rats with cirrhosis were treated with 300 microg LPS/100 g body weight, and 1 g/rat of glycine about four h prior to LPS. After three h of LPS treatment, blood and tissues were collected for various measurements. Kupffer cells were isolated from male Wistar rats and cultured, and divided into five groups. Supernatant was harvested at 3 h after treatment with LPS for measurement of tumor necrosis factor-alpha (TNF-alpha).. Our results showed that in rats with cirrhosis, slowed and deepened breath with occasional pause was. PaO2, PaCO2 and standard bicarbonate (SB) in arterial blood were decreased. Arterial O2 and actual bicarbonate (AB) were markedly decreased. There was a close correlation between decreased O2 and endotoxin. Metabolic acidosis accompanying respiratory alkalosis was the primary type of acid-base imbalance. The alveolar-arterial oxygen gradient was sharply widened. Massive accumulation of giant macrophages in the alveolar spaces and its wall and widened alveolar wall architecture were observed. The number of bacterial translocations in mesenteric lymph nodes increased. The ratio of TC99M-MAA brain-over-lung radioactivity rose. Endotoxin, and TNF-alpha, endothelin-1 (ET-1), nitric oxide (NO) in plasma and ET-1, carbon monoxide (CO) in lung homogenates increased. After administration of a given dosage of LPS in rats with cirrhosis, various pathological parameters worsened. Plasma level of endotoxin was related to TNF-alpha, ET-1, NO in plasma and ET-1, NO, CO in lung homogenates. TNF-alpha level was related to ET-1 and NO in plasma and lung homogenates and CO in lung homogenate as well. The level of TNF-alpha increased after infusion of LPS into culture supernatant of Kupffer cells in vitro. However, TNF-alpha significantly decreased after pretreatment with glycine, PD98059 and SB212850. Glycine could antagonize the effect of LPS in vivo and in vitro.. Intestinal endotoxemia accompanying by cirrhosis may be an important mechanism in the development of hepatopulmonary syndrome in rats. Overproduction of TNF-alpha due to endotoxin stimulation of Kupffer cells via mitogen-activated protein kinase (MAPK) signal transduction pathway may be a major mechanism mediating the pathologic alterations of hepatopulmonary syndrome.

Topics: Acid-Base Imbalance; Acidosis; Animals; Bacterial Translocation; Brain; Carbon Monoxide; Endothelin-1; Endotoxemia; Hepatopulmonary Syndrome; Kupffer Cells; Lipopolysaccharides; Liver Cirrhosis; Lung; Male; MAP Kinase Signaling System; Nitric Oxide; Rats; Rats, Wistar; Respiratory Mechanics; Sulfhydryl Compounds; Technetium Tc 99m Aggregated Albumin; Tumor Necrosis Factor-alpha

We examined the role of thromboxane A2 (TXA2) in LPS-induced hyperresponsiveness of hepatic portal circulation to endothelins (ETs) and whether Kupffer cells are the primary source of TXA2 release in response to ET-1 in endotoxemia. After 6 h of LPS (1 mg/kg body wt ip) or saline (control), liver was isolated and perfused with recirculating Krebs-Henseleit bicarbonate buffer at a constant flow rate (100 ml.min(-1).kg body wt(-1)). ET-1 (10 pmol/min) was infused for 10 min. Portal pressure (PP) was continuously monitored during perfusion. Perfusate was sampled for enzyme immunoassay of thromboxane B2 (TXB2; the stable metabolite of TXA2) and lactate dehydrogenase (LDH) assay. ET-1 infusion resulted in a significantly greater increase of PP in the LPS group than in controls. Both TXA2 synthase inhibitor furegrelate (Fureg) and TXA2 receptor antagonist SQ-29548 (SQ) substantially blocked enhanced increase of PP in the LPS group (4.9 +/- 0.4 vs. 3.6 +/- 0.5 vs. 2.6 +/- 0.6 mmHg for LPS alone, LPS + Fureg, and LPS + SQ, respectively; P < 0.05) while having no significant effect on controls. GdCl3 for inhibition of Kupffer cells had similar effects (4.9 +/- 0.4 mmHg vs. 2.9 +/- 0.4 mmHg for LPS alone and GdCl3 + LPS, respectively; P < 0.05). In addition, the attenuated PP after ET-1 was found concomitantly with significantly decreased releases of TXB2 and LDH in LPS rats treated with Fureg, SQ, and GdCl3 (886.6 +/- 73.4 vs. 110.8 +/- 0.8 vs. 114.8 +/- 54.7 vs. 135.2 +/- 45.2 pg/ml, respectively; P < 0.05). After 6 h of LPS, Kupffer cells in isolated cell preparations released a significant amount of TXA2 in response to ET-1. These results clearly indicate that hyperresponsiveness of hepatic portal circulation to ET-1 in endotoxemia is mediated at least in part by TXA2-induced receptor activation, and Kupffer cells are likely the primary source of increased TXA2 release.

Topics: Animals; Benzofurans; Bridged Bicyclo Compounds, Heterocyclic; Endothelin-1; Endotoxemia; Fatty Acids, Unsaturated; Gadolinium; Hydrazines; Kupffer Cells; Lipopolysaccharides; Liver; Male; Portal Pressure; Portal System; Rats; Rats, Sprague-Dawley; Receptors, Thromboxane; Thromboxane A2; Thromboxane-A Synthase

To measure plasma endothelin-1 (ET-1) concentrations and digital blood flow in clinically endotoxemic horses.. 36 adult horses that underwent emergency celiotomy for primary gastrointestinal tract disease.. On days 2 and 5 following surgery, Doppler ultrasonographic digital arterial blood flow measurements were obtained. Hematologic and biochemical analyses were performed, and plasma concentrations of ET-1 and endotoxin (lipopolysaccharide) were determined. A scoring system based on 9 clinical variables was used to assign horses to group B (quartile with greatest cumulative score) or group A (remaining 3 quartiles). Follow-up at 2.5 years was obtained by telephone questionnaire.. For all horses on day 2, median (interquartile values) plasma ET-1 concentrations were 1.4 (0.8, 1.7) pg/mL, whereas on day 5, plasma ET-1 concentrations were 1.0 (0.5, 1.6) pg/mL. On day 2, digital blood flow was 0.057 (0.02, 0.07) mL/min in group A horses and 0.035 (0.02, 0.03) mL/min in group B horses. On day 5, plasma ET-1 concentration was significantly (73%) higher in group B horses, compared with group A horses. Thirty of 36 horses were alive at 2.5 years; group A horses were more likely to have survived (odds ratio, 25; 95% confidence interval, 2.4 to 262). Significant associations were found between an increase in digital pulses, hoof wall temperatures, or both and increased digital blood flow (0.14 vs 0.04 mL/min) on day 2 and increased digital arterial diameter (0.32 vs 0.23 cm) on day 5.. Horses with more severe endotoxemia had decreased digital blood flow, increased plasma ET-1 concentrations, and decreased long-term survival.

Topics: Animals; Blood Chemical Analysis; Blood Pressure; Body Temperature; Digestive System Surgical Procedures; Endothelin-1; Endotoxemia; Female; Follow-Up Studies; Foot; Gastrointestinal Diseases; Heart Rate; Horse Diseases; Horses; Leukocyte Count; Lipopolysaccharides; Male; Respiration; Surveys and Questionnaires; Ultrasonography

Studies in vitro reveal that endothelin-1 (ET-1) activates the alpha isoform of protein kinase C (PKC-alpha) in cultures of endothelial cells, thereby deranging cellular integrity. Sepsis and endotoxemia are associated with increased plasma concentrations of ET-1 that induce acute lung injury (ALI). We recently reported that non-selective ET-1 receptor blockade attenuates ALI in sheep by reducing the endotoxin-induced increase in extravascular lung water index (EVLWI). The aim of this study was to find out whether this attenuation is associated with reduced translocation of PKC-alpha from the cytosolic to the membrane fraction of lung tissue homogenate.. Seventeen awake, instrumented sheep were randomly assigned to a sham-operated group (n = 3), a lipopolysaccharide (LPS) group (n = 7) receiving an intravenous infusion of Escherichia coli 15 ng/kg per min for 24 hours, and a tezosentan group (n = 7) subjected to LPS and, from 4 hours, an intravenous injection of tezosentan 3 mg/kg followed by infusion at 1 mg/kg per hour for the reminder of the experiment. Pulmonary micro-occlusion pressure (Pmo), EVLWI, plasma concentrations of ET-1, tumor necrosis factor-a (TNF-a), and interleukin-8 (IL-8) were determined every 4 hours. Western blotting was used to assess PKC-alpha.. In non-treated sheep a positive correlation was found between the plasma concentration of ET-1 and Pmo in the late phase of endotoxemia (12 to 24 hours). A positive correlation was also noticed between Pmo and EVLWI in the LPS and the LPS plus tezosentan groups, although the latter was significantly reduced in comparison with LPS alone. In both endotoxemic groups, plasma concentrations of ET-1, TNF-alpha, and IL-8 increased. In the LPS group, the cytosolic fraction of PKC-alpha decreased by 75% whereas the membrane fraction increased by 40% in comparison with the sham-operated animals. Tezosentan completely prevented the changes in PKC-alpha in both the cytosolic and the membrane fractions, concomitantly causing a further increase in the plasma concentrations of ET-1, TNF-alpha, and IL-8.. In endotoxemic sheep, ET-1 receptor blockade alleviates lung injury as assessed by a decrease in EVLWI paralleled by a reduction in Pmo and the prevention of activation of PKC-alpha.

Topics: Animals; Endothelin A Receptor Antagonists; Endothelin-1; Endotoxemia; Enzyme Activation; Escherichia coli Infections; Interleukin-8; Protein Kinase C; Pyridines; Respiratory Distress Syndrome; Sheep; Tetrazoles; Tumor Necrosis Factor-alpha; Vasodilator Agents

We tested the hypothesis that metalloendopeptidase inhibition using phosphoramidon during induction of endotoxemia 24 h later would down-regulate the protein expression of myocardial inducible nitric oxide synthase (iNOS) and phosphorylation of p38-mitogen-activated protein kinase (p38-MAPK). Male Sprague-Dawley rats (350-400 g) were randomly divided into sham-treated and LPS-treated groups (Escherichia. coli lipopolysaccharide [LPS] 2 mg/kg bolus + 2 mg/kg infusion for 30 min). The animals in each group were further subdivided into vehicle- and phosphoramidon (1 mg/kg bolus)-treated subgroups. Blood and heart samples were collected at 2- and 24-h postendotoxemia/phosphoramidon treatment. LPS at 2 h after its administration produced a significant decrease in mean arterial pressure that was blocked by phosphoramidon treatment. LPS at 2 and 24 h produced a significant elevation in the concentration of left ventricular endothelin-1 (ET-1) both in heart and plasma as compared with control group. This LPS-induced left ventricular ET-1 elevation at 24 h was significantly reduced by phosphoramidon. No significant alterations were observed in the myocardial protein expression of preproET-1, iNOS, and eNOS at 2 h post LPS. In 24-h post treatment groups phosphoramidon upregulated the expression of myocardial preproET-1 protein both in control and endotoxemic rat groups. Also, LPS-induced upregulated protein expression of myocardial-inducible nitric oxide synthase and increased levels of nitric oxide byproducts at 24 h were blocked by phosphoramidon. Phosphoramidon inhibited LPS-induced down-regulated expression of myocardial endothelial nitric oxide synthase and upregulated p38-MAPK phosphorylation. These results indicated that inhibition of metalloendopeptidase during induction of endotoxemia could regulate the phosphorylation of myocardial p38-MAPK and iNOS protein expression at 24-h post endotoxemia. We concluded that inhibition of metalloendopeptidases during early endotoxemia not only decreased the biosynthesis of ET-1 in heart locally but also simultaneously down-regulated myocardial protein expression of iNOS and p38-MAPK phosphorylation in the later stage of endotoxemia.

Topics: Animals; Blood Pressure; Endothelin-1; Endotoxemia; Glycopeptides; Heart; Lipopolysaccharides; Male; Metalloendopeptidases; Mitogen-Activated Protein Kinases; Models, Biological; Myocardium; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Protease Inhibitors; Rats; Rats, Sprague-Dawley

Cirrhosis predisposes the liver to secondary stresses such as endotoxemia possibly via dysregulation of the hepatic portal circulation secondary to imbalanced upregulation of vascular stress genes. In this study we determined the effect of cirrhosis on hepatic vasoregulatory gene expression in response to endotoxin (LPS, i.p., 1 mg/kg). Cirrhosis was induced by bile duct ligation (BDL) for 21 days in male Sprague-Dawley rats. Plasma and liver samples were taken 6 h following an injection of LPS for alanine aminotransferase (ALT) assays and RT-PCR analysis of mRNA levels for genes of interest: endothelin (ET-1), its receptors ET(A) and ET(B), endothelial nitric oxide synthase (eNOS), inducible NOS (iNOS), and heme oxygenase-1 (HO-1). ALT release increased by 5.5-fold in the BDL animals and 9.9-fold in BDL + LPS compared to sham. ET-1 mRNA was increased by either LPS or BDL treatment alone and increased significantly more in BDL + LPS compared to sham + LPS. mRNA levels for ET(B) receptors showed no change, whereas ETA transcripts decreased in BDL animals compared to sham, with no significant difference between the saline and LPS treatment groups. The resultant increased ratio of ET(B) over ET(A) in BDL animals was reflected functionally in the portal pressure responses to ET(A) and ET(B) agonists ET-1 and IRL-1620 (a specific ETB receptor agonist). The pressor response to ET-1 was attenuated, while the response to IRL-1620 was similar in BDL and sham. eNOS mRNA levels did not increase in response to either BDL or LPS or a combination of both compared to sham. The increase in iNOS mRNA was attenuated in BDL + LPS compared to sham + LPS. HO-1 expression increased significantly in sham + LPS, but failed to increase in BDL + LPS. Taken collectively, significantly greater induction of the constrictor ET-1 over the dilation forces (i.e., eNOS, iNOS, and HO-1) was observed in BDL + LPS. This suggests a compromised ability of the cirrhotic liver to upregulate sufficient dilatory forces to counterbalance the constrictive effect of ET-1 upon a secondary insult of endotoxemia. These results may partly explain the increased susceptibility of cirrhotic livers to injury as a result of endotoxemia.

Topics: Alanine Transaminase; Animals; Blood Pressure; Endothelin-1; Endotoxemia; Gene Expression; Heme Oxygenase (Decyclizing); Heme Oxygenase-1; Lipopolysaccharides; Liver Cirrhosis; Male; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; RNA, Messenger; Vasoconstriction; Vasodilation

Endothelin 1 (ET-1) is a potent vasoactive peptide that acts at sinusoidal and extrasinusoidal sites in the liver. Sensitivity to ET-1 increases in LPS-primed animals and is associated with impaired liver microcirculation in these animals. We hypothesized that LPS priming leads to an exacerbation in the impaired oxygen delivery in response to intraportal infusion of ET-1. Rats were studied 24 h after LPS injection (1 mg/kg, i.p.). Surface PO2 was determined using a recently developed technology of O2 mapping. The baseline portal pressure was higher in LPS-primed animals (P < 0.05), and increased to'similar magnitude as sham animals after a 10-min infusion of ET-1. The resultant portal pressure remained elevated in LPS compared to sham animals. There was no significant difference in baseline mean arterial pressure, and no significant systemic response to ET-1 in either group. In contrast to the macrohemodynamic, the decrease in tissue surface PO2 in response to ET-1 infusion was potentiated by LPS treatment (increased from baseline levels 33.8+/-9 to 46.8+/-8.3 in sham; 42.3+/-9.1 to 69+/-6.5 gray scale units in LPS; P < 0.01, sham vs. LPS) at end of infusion of ET-1 for 10 min. This indicates tissue hypoxia in response to ET-1, which is exacerbated in livers from LPS-primed animals compared to sham. Frequency distribution analysis showed a shift in mode from lower intensity (higher PO2) to areas with higher fluorescent intensity ranges (lower PO2), indicating areas with shut down in perfusion in LPS-treated animals. In the whole liver, ET-1 suppressed oxygen consumption, and this response was potentiated by LPS pretreatment. We propose that ET-1 impairs oxygen delivery in the liver during endotoxemia, resulting in areas of focal hypoxia. This response is possibly due to potentiated action of ET-1 at both sinusoidal and extrasinusoidal sites in the liver during endotoxemia.

Topics: Animals; Endothelin-1; Endotoxemia; Hemodynamics; Hypoxia; In Vitro Techniques; Lipopolysaccharides; Liver; Male; Oxygen; Oxygen Consumption; Perfusion; Rats; Rats, Sprague-Dawley

Mechanisms underlying hepatic microcirculatory failure during endotoxemia are incompletely understood. Because endothelin-1 (ET-1) has been implicated in endotoxin-induced liver injury, we investigated the hepatic ET-1 system in endotoxin-treated rats.. Rats were treated with endotoxin (Escherichia coli lipopolysaccharide; 3 mg/kg, i.p.), and various determinations were made 24 h later.. Endotoxin treatment caused 11.2 +/- 1.6% weight loss, a decrease in mean arterial pressure (MAP; 96 +/- 5 mmHg vs 108 +/- 3 mmHg; P < 0.05) and an increase in portal pressure (11.6 +/- 1.3 mmHg vs 7.4 +/- 1 mmHg; P < 0.02). No significant changes in the serum levels of liver enzymes or hepatocellular necrosis were observed. Endotoxin caused increases in hepatic ET-1 (from 345 +/- 31 to 565 +/- 38 pg/g; P < 0.01), ET-1 receptor density (from 179 +/- 16 to 340 +/- 26 fmol/mg; P < 0.02), and mRNA expression of preproendothelin-1, and ET(A) and ET(B) receptors. While the serum nitric oxide (nitrite +/- nitrate) concentration was increased in endotoxin-treated rats, that of ET-1 remained unchanged. A mixed ET(A)/ET(B) receptor antagonist, TAK-044 (10 mg/kg, i.v.), reduced the weight loss from 11.2 +/- 1.6% to 5.9 +/- 2.9% (P < 0.05) and the portal pressure from 11.6 +/- 1.3 mmHg to 8.6 +/- 0.7 mmHg (P < 0.05) in endotoxin-treated rats. The mixed ET(A)/ET(B) receptor antagonist also caused an increase in serum ET-1 concentration, but did not affect serum nitric oxide and MAP in endotoxin-treated rats.. These results suggest that the upregulated hepatic ET-1 system is an important mechanism of increased portal resistance and related complications of endotoxemia.

Topics: Animals; Blood Pressure; Body Weight; Endothelin-1; Endotoxemia; Endotoxins; Liver; Male; Nitric Oxide; Peptides, Cyclic; Rats; Rats, Sprague-Dawley; Receptors, Endothelin; RNA, Messenger; Up-Regulation

1. In conscious, freely moving, male, Long Evans rats, regional haemodynamic responses to exogenous endothelin-1 (ET-1; 25, 50 and 250 pmol kg(-1) i.v.) were assessed in the presence of vehicle, or the selective ET(A)-receptor antagonist, SB 234551. On the following day, the effects of SB 234551 on the haemodynamic responses to lipopolysaccharide (LPS) infusion (150 microg kg(-1) h(-1), i.v.) were determined. 2. When SB 234551 was given i.v. by primed infusion at a dose of 0.3 mg kg(-1) bolus, 0.3 mg kg(-1) h(-1) infusion, it caused selective inhibition of the vasoconstrictor effects of exogenous endothelin-1, whereas at a dose of 1 mg kg(-1), 1 mg kg(-1) h(-1), SB 234551 also inhibited some of the vasodilator effects of endothelin-1. 3. Infusion of LPS, in the presence of vehicle, caused a short-lived (1 - 2 h) hypotension, tachycardia, and vasodilatation in renal, superior mesenteric and hindquarters vascular beds. Thereafter, blood pressure, heart rate and mesenteric vascular conductance returned to baseline values, but renal vasodilatation persisted, and there was vasoconstriction in the hindquarters. 4. In the presence of SB 234551 (0.3 mg kg(-1), 0.3 mg kg(-1) h(-1)), the early (1 - 2 h) cardiovascular responses to LPS infusion were unaffected, but the subsequent recovery of mean arterial blood pressure was impaired, due to developing vasodilatation in the mesenteric and, to a lesser extent, hindquarters, vascular beds. SB 234551 had no effect on the renal haemodynamic responses to LPS infusion. 5. The results confirm an important, regionally-selective, vasoconstrictor role for endogenous endothelin in this model of endotoxaemia.

Topics: Animals; Blood Pressure; Consciousness; Dioxoles; Endothelin Receptor Antagonists; Endothelin-1; Endotoxemia; Heart Rate; Hemodynamics; Lipopolysaccharides; Male; Nitric Oxide; Pyrazoles; Rats; Rats, Long-Evans; Receptor, Endothelin A; Receptors, Endothelin; Time Factors

To explore the effect of endotoxin on the development of cirrhosis.. The cirrhosis model with intestinal endotoxemia was made by oral intake of 0.03% thioacetamide for four months to observe the effect of endotoxin on the hepatic collagen contents in both thioacetamide and thioacetamide + lipopolysaccharide groups and to detect the contents of tumor necrosis factor-alpha (TNF-alpha), endothelin-1 (ET-1), nitric oxide (NO), and malondialdehyde (MDA) in the plasma and the hepatic homogenate.. The contents of TNF-alpha, ET-1, NO, and MDA in the plasma and the hepatic homogenate and the content of collagen in the hepatic tissue in the two groups were higher than those in the normal control group.. Endotoxin can accelerate liver fibrosis and the formation of cirrhosis.

Topics: Animals; Collagen; Endothelin-1; Endotoxemia; Liver Cirrhosis, Experimental; Male; Malondialdehyde; Nitric Oxide; Rats; Rats, Wistar; Tumor Necrosis Factor-alpha

Endothelin-1 (ET-1) levels are markedly increased in sepsis. Since ET-1 is primarily transcriptionally regulated, there should be a corresponding increase in pre-pro-endothelin-1 (ppET-1). Our objective was to determine whether ppET-1 is increased in pigs with a low systemic vascular resistance. We also examined the distribution of ET-1 and the regulation of endothelin-converting enzyme 1 (ECE-1), the rate limiting enzyme in ET-1 production. We anesthetized and ventilated 16 pigs. We measured arterial, pulmonary, and central venous pressures, as well as cardiac output. ET-1 was measured by radioimmunoassay in plasma and in multiple tissues. We infused 20 microg/kg of endotoxin over 2 h and then sacrificed the animals. ppET-1 and ECE-1 mRNA were assessed by Northern analysis. We performed immunohistochemistry for the assessment of tissue ET-1 and ECE-1. The systemic vascular resistance rose at 30 min, but fell by 120 min. Plasma ET-1 more than doubled by 2 h. However, there was no change in the concentration of ET-1 in any tissue except in the pulmonary artery. By immunohistochemistry, there was also no change in ET-1 in aorta, vena cava, heart, lung, liver, and kidney. Distribution of ECE-1 followed that of ET-1 on immunohistochemistry. There was a significant increase in ppET-1 mRNA in liver, kidney papillae, and vena cava, and a tendency for an increase in other tissues. This was paralleled by an increase in ECE-1 mRNA. In conclusion, the amount of ECE-1 mRNA and protein parallel those of ET-1. Endotoxemia is associated with a marked increase in plasma ET-1 and an increase in ppET-1 and ECE-1 mRNA in multiple tissues; however, there was no significant change in tissue ET-1 except in the pulmonary artery. The rise in plasma levels without a change in tissue levels suggests a greater release into the vasculature in sepsis than under normal conditions.

Topics: Animals; Aspartic Acid Endopeptidases; Blotting, Northern; Endothelin-1; Endothelin-Converting Enzymes; Endotoxemia; Hemodynamics; Immunohistochemistry; Metalloendopeptidases; Swine

To investigate whether adenosine protects against endotoxin-induced increments in extravascular lung water content.. Prospective, randomized, animal study.. University research laboratory.. Twenty-one anesthetized juvenile pigs.. The animals were divided into two groups subjected to endotoxin infusion: Endotoxin alone (n = 7), or endotoxin combined with adenosine infusion (n = 7) administered during the whole experimental period. Two other groups were exposed to anesthesia alone (n = 4) or adenosine infusion alone (n = 3), respectively.. Central hemodynamic variables and extravascular lung water, as assessed by the thermal dye dilution double indicator technique, were monitored. Plasma endothelin-1 concentrations were measured hourly. Extravascular lung water increased significantly in response to endotoxemia (p <.001) along with an increase in pulmonary microvascular pressure (P(mv) [p <.01]). Although the Pmv increased less in endotoxemic animals exposed to adenosine infusion, no intergroup difference was found. From 4 through 6 hrs, adenosine-treated pigs displayed only half of the extravascular lung water content of nontreated animals (p <.01). The latter did not differ from that of anesthetized controls receiving anesthesia or adenosine alone. Adenosine administered alone had no effect on P(mv). In pigs receiving adenosine alone, extravascular lung water content reached nadir after 3 hrs. In both endotoxin groups, plasma endothelin-1 concentration increased two-fold, peaking 4-6 hrs after the start of endotoxin infusion (p <.001).. The endotoxin-induced increase in lung extravascular water was hampered by intravenously infused adenosine in the presence of a nonsignificantly reduced microvascular pressure. This leaves reduced microvascular permeability the most likely reason for the beneficial effect of adenosine.

Topics: Adenosine; Analysis of Variance; Animals; Blood Pressure; Capillary Permeability; Endothelin-1; Endotoxemia; Escherichia coli Infections; Extravascular Lung Water; Hemodynamics; Lung; Microcirculation; Pulmonary Gas Exchange; Random Allocation; Respiratory Distress Syndrome; Swine; Vasodilator Agents

High volume hemofiltration (HVHF) (200 ml/kg/h) improves hemodynamics in experimental septic shock but is difficult to apply clinically. Accordingly, we studied whether less intensive HVHF (80 ml/kg/h) can still improve hemodynamics in experimental septic shock. We also investigated its effect on the serum concentrations of several inflammatory mediators, including endothelin (ET-1), endotoxin (LPS), tumor necrosis factor-alpha (TNF-alpha), and 6-keto prostaglandin F(1alpha) (6-kepto PGF(1alpha)). Sixteen anesthetized dogs were connected to a continuous veno-venous hemofiltration (CVVH) (filtration: 80 ml/kg/h) or sham circuit and endotoxin (0.5 mg/kg) was infused intravenously over 5 min. Hemodynamic variables were measured at baseline and at 15, 45, 90, and 180 min. The major hemodynamic finding was that endotoxin-induced hypotension was significantly attenuated by intensive CVVH (p < 0.04). Changes in cardiac output and right ventricular ejection fraction were equal in both groups. ET-1 levels, but not LPS, TNF-alpha, or 6-keto PGF(1alpha), were lower during CVVH (p = 0.042). Endotoxin or TNF-alpha were not found in the ultrafiltrate. Median clearances of ET-1 and 6-keto PGF(1alpha) during intensive CVVH were 8.8 and 25.9 ml/m, respectively. We conclude that intensive CVVH attenuates the early component of endotoxin-induced hypotension and reduces serum concentrations of endothelin-1. The effect of CVVH on blood pressure is not explained by convective clearance of the mediators in question.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Blood Pressure; Cardiac Output; Dogs; Endothelin-1; Endotoxemia; Hemodynamics; Hemofiltration; Inflammation Mediators; Lipopolysaccharides; Male; Tumor Necrosis Factor-alpha

Opioid receptor antagonists can act centrally and peripherally. It is unclear if these 2 pathways differentially mediate the perfusion-associated effects of opioid antagonism during endotoxemia. Male, Sprague-Dawley rats (340-390 g) were surgically prepared with left ventricular, tail artery, and jugular vein catheters 24 h before experiments were begun. Conscious, unrestrained rats were challenged with Escherichia coli lipopolysaccharide (LPS; 2 mg/kg/hr over 30 min) infusion. Measurements of regional blood flows were made using radioactive microspheres prior to (baseline), and at 60 and 120 min after LPS infusion. Saline (1 mL/kg bolus + 0.5 mL/kg/h infusion), naloxone (Nlx; 4 mg/kg bolus + 2 mg/kg/h infusion), or naloxone methyl bromide (Nlx-mb; 4.64 mg/kg, bolus + 2.32 mg/kg/h infusion) were administered 40 min after LPS infusion was begun. Nlx-mb does not cross the blood-brain barrier, and was thus used to differentiate central from peripherally mediated responses. At the end of each experiment, blood samples were collected for determination of ET-1 and nitric oxide metabolites (NOx = NO3 + NO2) using enzyme-linked immunosorbent assay (ELISA) and Griess reaction methods, respectively. Endotoxemia produced a significant decrease in cardiac output and an increase in systemic vascular resistance. Treatment with Nlx or Nlx-mb significantly attenuated the endotoxin-induced elevation in systemic vascular resistance and the decrease in cardiac output at 60 min after induction of endotoxemia compared with their respective baseline values. Nlx and Nlx-mb also attenuated the endotoxin-induced increases in hepatic portal and skeletal vascular resistances. These observations suggested that the ameliorative effect of Nlx on endotoxemia-induced regional vascular resistance alterations was mediated via peripheral opioid receptor mechanisms. However, although Nlx attenuated the endotoxin-induced decreases in the blood flow to the stomach and pancreas, Nlx-mb attenuated the endotoxin-induced decreases in the blood flow to the small intestine and cecum, in addition to the pancreas and, to some extent, the stomach. As such, separate central and peripherally mediated actions of opioid receptor antagonism were indicated. Nlx also resulted in an increase in the plasma levels of ET-1 only, whereas Nlx-mb increased the plasma levels of ET-1 and NOx. These observations suggest that separate central and peripheral effects of opioids during endotoxemia play a role in the assoc

Topics: Animals; Blood Pressure; Cardiac Output; Endothelin-1; Endotoxemia; Heart Rate; Male; Naloxone; Narcotic Antagonists; Nitric Oxide; Rats; Rats, Sprague-Dawley; Regional Blood Flow; Vascular Resistance

Heme oxygenase (HO)-1 is an enzyme that degrades heme to generate CO (a vasodilatory gas), iron, and the potent antioxidant bilirubin. A disease process characterized by decreases in vascular tone and increases in oxidative stress is endotoxic shock. Moreover, HO-1 is markedly induced in multiple organs after the administration of endotoxin (lipopolysaccharide [LPS]) to mice.. To determine the role of HO-1 in endotoxemia, we administered LPS to mice that were wild-type (+/+), heterozygous (+/-), or homozygous null (-/-) for targeted disruption of HO-1. LPS produced a similar induction of HO-1 mRNA and protein in HO-1(+/+) and HO-1(+/-) mice, whereas HO-1(-/-) mice showed no HO-1 expression. Four hours after LPS, systolic blood pressure (SBP) decreased in all the groups. However, SBP was significantly higher in HO-1(-/-) mice (121+/-5 mm Hg) after 24 hours, compared with HO-1(+/+) (96+/-7 mm Hg) and HO-1(+/-) (89+/-13 mm Hg) mice. A sustained increase in endothelin-1 contributed to this SBP response. Even though SBP was higher, mortality was increased in HO-1(-/-) mice, and they exhibited hepatic and renal dysfunction that was not present in HO-1(+/+) and HO-1(+/-) mice. The end-organ damage and death in HO-1(-/-) mice was related to increased oxidative stress.. These data suggest that the increased mortality during endotoxemia in HO-1(-/-) mice is related to increased oxidative stress and end-organ (renal and hepatic) damage, not to refractory hypotension.

Topics: Animals; Endothelin-1; Endotoxemia; Female; Heme Oxygenase (Decyclizing); Heme Oxygenase-1; Hypotension; Lipopolysaccharides; Lung; Membrane Proteins; Mice; Mice, Inbred BALB C; Mortality; Multiple Organ Failure; Oxidative Stress; RNA, Messenger

Endotoxin-induced vascular hyporesponsiveness could potentially involve alterations of vascular smooth muscle (VSM) myoplasmic free calcium (Ca(m)) mobilization mechanisms. Contractile function and Ca(m)(fura-2 microfluorometry) regulation were evaluated in vitro using coronary (COR) and mesenteric (MES) artery preparations (100-250 microm inner diameter) isolated from guinea pigs 16 h after intraperitoneal (i.p.) injection of either saline (control; CON) or Escherichia coli endotoxin lipopolysaccharide (LPS; 4 mg/kg). Concentration-response relationships to K+ (5-100 mM) were significantly enhanced in both COR and MES arteries isolated from LPS-treated animals. In contrast, contractile responses to prostaglandin F2alpha (PGF2alpha; 1-100 microM) were markedly impaired in COR and MES arteries from LPS-treated animals, while endothelin-1 (ET; 1-100 nM)-mediated contractile responses of these arteries were enhanced at the maximal dose (100 nM). In COR arteries, PGF2alpha (1-100 microM) and ET (1-100 nM) produced biphasic increases in Ca(m) in both CON and LPS groups. No significant differences were observed in either the initial transient peak or secondary sustained Ca(m) responses between groups, suggesting a lack of effect of LPS upon intracellular Ca2+ release or Ca2+ influx mechanisms in COR arteries. Exposure of MES arteries to PGF2alpha and ET produced concentration-dependent increases in Ca(m) in both groups. However, Ca(m) responses of MES arteries lacked initial peak responses, suggesting potential differences in Ca(m) mobilization between COR and MES arteries. Ca(m) responses to K+ (80 mM) and PGF2alpha (1-100 microM) were similar in MES arteries from both groups; however, ET-mediated increases in Ca(m) were significantly blunted in LPS compared with CON MES arteries. Thus, endotoxemia produced differential effects upon depolarization (K4) and receptor (PGF2alpha, ET)-mediated contractile responses in both COR and MES arteries. Reductions in VSM Ca(m) mobilization appear unlikely as a mechanism for LPS-induced impairment of contractile function of COR and MES arteries; other mechanisms (i.e., decreased Ca2+ sensitivity of contractile proteins) may be involved in effects of LPS upon VSM function of COR and MES arteries.

Topics: Animals; Calcium; Coronary Vessels; Dinoprost; Endothelin-1; Endotoxemia; Fura-2; Guinea Pigs; Lipopolysaccharides; Mesenteric Arteries; Muscle, Smooth, Vascular; Potassium; Vasoconstrictor Agents

During endotoxemia, there is a marked and intractable decrease in systemic blood pressure, as well as profound vasoconstriction of the renal artery, thereby leading to septic shock and acute renal failure. The purpose of this study was to elucidate the effect of endothelin-1, a potent endothelium-derived vasoconstrictor peptide, on the hemodynamic and renal vascular changes seen in endotoxemia.. Prospective, comparative, experimental study.. Laboratory at a university hospital.. Thirty-two male mongrel dogs (12.1+/-0.4 kg) under pentobarbital anesthesia.. Four groups of animals were studied: a) the lipopolysaccharide (LPS) group (n = 10), which received LPS (250 ng/kg/min for 2 hrs); b) the TAK-044 (a nonselective endothelinA/ endothelinB receptor antagonist) plus LPS group (n = 12), which received a bolus of TAK-044 (5 mg/kg) 0.5 hr before the start of LPS infusion; c) the TAK-044 plus vehicle group (n = 5), which received the same dose of TAK-044 0.5 hr before the start of vehicle infusion; and d) the control group (n = 5), which received only vehicle infusion.. Changes in systemic and renal hemodynamics, blood gas, and renal function were measured at baseline, and at 0.5, 1, 2, 3, and 4 hrs. Infusion of LPS resulted in significant decreases in mean arterial pressure, arterial pH, Pao2, base excess, urine volume, renal blood flow, creatinine clearance, and urine osmolality. The administration of TAK-044 before LPS infusion did not affect the LPS-induced hypotension. In contrast, the receptor antagonist prevented LPS-induced metabolic acidosis and hypoxemia, and improved LPS-induced decreases in urine volume, renal blood flow, creatinine clearance, and urine osmolality, whereas TAK-044 or vehicle administered alone resulted in no significant hemodynamic or blood gas changes. Plasma endothelin-1 concentrations significantly increased after LPS infusion, with or without TAK-044.. The present study suggests that endothelin-1 plays an important role in the impaired renal hemodynamics and renal function associated with endotoxemia, and that endothelin receptor antagonists may be useful as therapeutic agents for acute renal failure during endotoxemia.

Topics: Acute Kidney Injury; Animals; Blood Gas Analysis; Critical Care; Dogs; Endothelin Receptor Antagonists; Endothelin-1; Endotoxemia; Hemodynamics; Lipopolysaccharides; Male; Peptides, Cyclic; Prospective Studies; Renal Circulation

Oxidative stress and inflammatory reactions associated with stresses that may lead to shock promote hepatic microcirculatory dysfunction, which may lead to hepatic injury. Because altered liver microcirculation may result from an imbalance in the expression of stress-induced vasoactive mediators, our study was conducted to investigate changes in the expression of genes encoding endothelin-1 (ET-1), its receptors, ET(A) and ET(B), heme-oxygenase 1 (HO-1), and inducible nitric oxide synthase (iNOS), using two different rat models of liver stress: ischemia/reperfusion of the liver and lipopolysaccharide (LPS)-induced endotoxemia. In ischemia/reperfusion experiments, rats were subjected to 1 h hepatic ischemia, followed by 6 h of reperfusion. Endotoxemia was induced by i.p. injection of LPS (1 mg/mL/kg body weight); rats were studied after 6 h. mRNA levels were estimated using semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) on total RNA samples prepared from experimental and sham control rat livers. In the ischemic reperfused livers the levels of mRNA for ET-1, ET(B), HO-1, and iNOS were significantly elevated. The fold increase versus sham was 2.5+/-1.1 (ET-1), 2.1+/-1.3 (ET(B)), 2.1+/-.8 (HO-1), and 6.4+/-3.9 (iNOS). In contrast, the expression of ET(A) receptor gene was reduced after ischemia/reperfusion (to 73+/-1% of sham). In the separate experiments we analyzed the same mRNAs levels after 1 h of ischemia (no reperfusion), and did not detect any changes. During endotoxemia we observed a marked increase in iNOS mRNA level (>24-fold), as well as a marked elevation of the other four mRNAs. The fold increase versus sham was 6.1+/-1.7, ET-1); 1.5+/-.3 (ET(A)); 1.6+/-.4 (ET(B)); and 2.4+/-.34 (HO-1). These results show that liver stress, induced by ischemia/reperfusion or LPS injection have characteristic patterns of vasoregulatory genes expression indicating that, although both stresses result in an increase in specific vascular reactivity, different pathways are involved in inducing the hepatic vascular stress response.

Topics: Animals; Endothelin-1; Endotoxemia; Gene Expression Regulation; Heme Oxygenase (Decyclizing); Heme Oxygenase-1; Ischemia; Lipopolysaccharides; Liver; Male; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; Reperfusion; Reperfusion Injury

The vasodilator nitric oxide (NO) is involved in the regulation of systemic blood pressure and local organ blood flow. Inhibitors of the constitutively expressed nitric oxide synthase in endothelial cells (eNOS), e.g., Nomega-nitro-L-arginine methyl ester hydrochloride (L-NAME), aggravated liver injury in a variety of models. On the other hand, inhibitors of the inducible NOS (iNOS), e.g., 2-aminoethyl-isothiourea (AET), were found to be beneficial during endotoxemia. The aim of this investigation was to study the effect of AET compared with L-NAME on liver microvascular blood flow and injury in more complex models with multiple insults, i.e., ischemia (20 min)-reperfusion (8 h) in combination with .5 mg/kg endotoxin (IRE). Male Fisher rats were treated with 10 mg/kg AET or L-NAME and subjected to IRE. At 8 h, liver injury (plasma ALT: 1320+/-164 U/L) was significantly increased in AET-treated (5,018+/-1,379 U/L) and L-NAME-treated groups (2,429+/-228 U/L). Each inhibitor attenuated microvascular blood flow (assessed by laser Doppler flowmetry) to a similar degree. In striking contrast, AET completely reversed the endotoxin-induced impairment of the microvascular blood flow and significantly protected against an endotoxin-induced liver injury (plasma ALT: 3,007+/-268 U/L (ET); 460+/-39 U/L (ET+AET)). Infusion of endothelin-1 reduced microvascular blood flow by 50-60% and caused liver injury. Our data demonstrated that an inhibitor of eNOS (L-NAME) has a consistent detrimental effect on liver injury during ischemia-reperfusion and endotoxemia mainly because it can cause additional ischemia by reducing the microvascular blood flow. However, selective inhibitors of iNOS (AET) can impair hepatic blood flow and aggravate the injury or improve blood flow and attenuate organ injury depending on the experimental model. These results suggest that iNOS inhibitors may not be universally beneficial and should be tested in a variety of experimental models of sepsis/endotoxemia before used in clinical settings.

Topics: Alanine Transaminase; Animals; beta-Aminoethyl Isothiourea; Blood Circulation; Blood Pressure; Endothelin-1; Endotoxemia; Glutathione; Ischemia; Liver; Liver Circulation; Male; Multiple Organ Failure; NG-Nitroarginine Methyl Ester; Nitrates; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitrites; Rats; Rats, Inbred Strains; Reperfusion

Hemoperfusion using polymyxin B-immobilized fiber (PMX-F) is reported to be an effective treatment for sepsis. The aim of the present study is to assess whether plasma endothelin-1 (ET-1) and ET-1 messenger RNA (mRNA) levels in peripheral-blood monocytes are altered in patients with sepsis and whether PMX-F treatment affects plasma ET-1 and monocyte ET-1 mRNA levels. Sixteen patients with sepsis and 20 healthy volunteers were included in this study. Plasma ET-1 concentration was measured by radioimmunoassay (RIA), and plasma levels of transforming growth factor-beta (TGF-beta), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1beta (IL-1beta) were measured by enzyme-linked immunosorbent assay (ELISA). Sixteen patients with sepsis were treated with direct hemoperfusion using PMX-F columns. Blood endotoxin levels decreased significantly from 35 to 10 pg/mL after two treatments of direct hemoperfusion, each for 2 hours. Patients with sepsis showed significantly increased levels of plasma ET-1 (P < 0.001) and monocyte ET-1 mRNA (P < 0.001) compared with healthy volunteers. However, no differences in plasma levels of TGF-beta, TNF-alpha, and IL-1beta existed between patients with sepsis and healthy volunteers. Increased plasma ET-1 levels and monocyte ET-1 mRNA levels in patients with sepsis decreased significantly after PMX-F treatment (P < 0.01). These data suggest that the secretion of ET-1 from peripheral-blood monocytes may be stimulated by endotoxin, and PMX-F treatment may be effective in reducing ET-1 secretion in patients with sepsis.

Topics: Adult; Aged; Anti-Bacterial Agents; APACHE; Endothelin-1; Endotoxemia; Female; Gram-Negative Bacterial Infections; Gram-Positive Bacterial Infections; Hemoperfusion; Humans; Male; Middle Aged; Monocytes; Polymyxin B; RNA, Messenger; Sepsis; Statistics, Nonparametric

A porcine model of endotoxemic shock was used to test the hypothesis that endothelins (ET) mediate the sustained increases in portal and pulmonary vascular resistances. Anesthetized pigs (n = 18) were instrumented and pretreated with 1) saline as a control; 2) indomethacin (Idm), a cyclooxygenase (Cox) inhibitor; or 3) Idm + bosentan (Bos), a mixed ET-receptor antagonist, and then were treated with endotoxin to produce shock and followed for 240 min. Global and regional hemodynamic parameters and plasma levels of ET-1 and thromboxane B2 were measured. The results show that 1) ET is independently responsible for the sustained increase in pulmonary vascular resistance; 2) ET and Cox products combine to increase portal venous resistance; 3) ET independently reduces cardiac output and attenuates or negates global systemic arterial vasodilation (presumptively mediated by nitric oxide) and exhibits regional differences, having little if any influence on the gut arterial bed. When considered with our prior study of nitric oxide regulation of the same beds in endotoxemic shock (N. Brienza, T. Ayuse, J. P. Revelly, C. P. O'Donnell, and J. L. Robotham, J. Appl. Physiol. 78: 784-792, 1995), the similarities between the portal venous and pulmonary arterial beds suggest that these two beds reflect phenomena occurring in microvascular and/or venous beds in multiple organs. The overall results suggest that a dynamic balance exists between NO and ET regulating arterial and microvascular and/or venous vasomotor activity during the evolution of endotoxemic shock.

Topics: Analysis of Variance; Animals; Bosentan; Cyclooxygenase Inhibitors; Endothelin Receptor Antagonists; Endothelin-1; Endothelins; Endotoxemia; Hemodynamics; Hypertension, Portal; Hypertension, Pulmonary; Indomethacin; Liver Circulation; Portal System; Pulmonary Artery; Pulmonary Circulation; Regional Blood Flow; Shock, Septic; Sulfonamides; Swine; Thromboxane B2; Vascular Resistance

Endothelin-1 (ET-1) is a vasoconstrictor and proinflammatory peptide, but its role in the vascular response to sepsis is unknown. After intraperitoneal injection of male Wistar rats (300 g) with 20 mg/kg of Salmonella enteritidis lipopolysaccharide (LPS), the expression of ET-1 mRNA was significantly increased in pulmonary artery and aorta within 1 h and arterial ET-1 concentration was elevated. Despite this increase in ET-1 production, there was no difference in baseline systemic or pulmonary arterial pressures between control and endotoxin-treated rats, and, furthermore, combined ETA/ETB receptor antagonism using bosentan produced reductions in systemic and pulmonary arterial pressures that were not greater than the modest fall seen in controls. However, bosentan completely antagonized the hemodynamic effects of exogenous ET-1 in controls but only weakly antagonized its effects in LPS animals. After LPS the initial (ETB-mediated) systemic hypotensive responses to ET-1 were attenuated, but the subsequent systemic pressor responses were not. By contrast, the increases in pulmonary arterial pressure in response to ET-1 and the ETB receptor agonist sarafotoxin S6c were significantly reduced in LPS animals. Vascular ET-1 mRNA expression and arterial ET-1 concentration are elevated after LPS treatment in rats, but the functional activity of ET-1 cannot be exposed by combined ETA/ETB receptor antagonism, possibly because of an alteration in the functional status of ET receptors.

Topics: Animals; Aorta; Blood Pressure; Bosentan; Endothelin Receptor Antagonists; Endothelin-1; Endotoxemia; Gene Expression; Hemodynamics; Lipopolysaccharides; Male; Pulmonary Artery; Rats; Rats, Wistar; Receptors, Endothelin; RNA, Messenger; Sulfonamides; Viper Venoms

To determine the possible adverse effects of human cross-linked hemoglobin in endotoxemia.. Prospective, controlled, laboratory trial.. Animal research laboratory.. New Zealand white rabbits.. Conscious rabbits received intravenous infusions of either lipopolysaccharide (LPS) alone (10 micrograms/kg, Escherichia coli 0111:B4), human hemoglobin cross-linked between the alpha chains (alpha alpha Hb, 0.7 g/kg), or both LPS and alpha alpha Hb. The cardiovascular effects of alpha alpha Hb and LPS as single agents or administered together were then studied in anesthetized rabbits.. Mortality in conscious animals that received alpha alpha Hb followed by LPS 4 hrs later (n = 5), or LPS and alpha alpha Hb at the same time (n = 6) was 60% and 67%, respectively. In anesthetized animals, infusion of both LPS and alpha alpha Hb (n = 6) resulted in hypoxia, lactic acidosis, ventricular arrhythmias, and decreased myocardial contractility and left ventricular pressure. In contrast, anesthetized rabbits that received alpha alpha Hb (n = 5) or LPS (n = 5) alone did not develop hypoxia, acidosis, alteration in myocardial contractility, or arrhythmias. Furthermore, death did not occur in any of the conscious animals that received either LPS (n = 7) or alpha alpha Hb (n = 4) as single agents.. In an animal model of nonlethal endotoxemia, infusion of alpha alpha Hb significantly increases mortality. Our data suggest that mortality may be due to the acute increased cardiopulmonary toxicity of alpha alpha Hb in animals with underlying endotoxemia.

Topics: Acidosis, Lactic; Animals; Arrhythmias, Cardiac; Cross-Linking Reagents; Drug Administration Schedule; Endothelin-1; Endotoxemia; Escherichia coli; Hemodynamics; Hemoglobin A; Humans; Hypoxia; Leukopenia; Lipopolysaccharides; Male; Myocardial Contraction; Rabbits

We have performed a series of experiments to study the effects of a newly developed antisense homology box-derived endothelin (ET) antagonist peptide (ETR-P1/fl) on the early hemodynamic changes in a hyperdynamic endotoxemic dog model. Mean arterial pressure (MAP), cardiac output (CO) and myocardial contractility (MC) were measured in closed-chest animals. Plasma levels of ET-1,2 were determined by radioimmunassay. A hyperdynamic circulatory response was elicited with a 2-hour infusion of 5.3 micrograms/kg of E. coli endotoxin (ETX). Control and ETX-treated animals received an infusion of ETR-P1/fl (0.1 mg/kg) i.v. ETX treatment decreased MAP and MC, increased initially CO, and a long lasting elevation in the plasma ET level was observed. In ETX-treated animals the administration of ETR-P1/fl significantly prolonged the increase in CO and inhibited the depression of MC. Our results suggest that treatment with the ET antagonist ETR-P1/fl may be advantageous in the early phase of endotoxemia.

Topics: Animals; Blood Circulation; Blood Pressure; Cardiac Output; Disease Models, Animal; Dogs; Endothelin Receptor Antagonists; Endothelin-1; Endothelin-2; Endotoxemia; Endotoxins; Escherichia coli; Escherichia coli Infections; Heart Rate; Hemodynamics; Infusions, Intravenous; Intercellular Signaling Peptides and Proteins; Myocardial Contraction; Peptides; Ventricular Function, Left; Ventricular Pressure

To study the distribution and significance of endothelin-1 (ET-1) and endothelin receptor A (ETAR) mRNA in liver after endotoxemia using situ hybridization.. 30 rats were randomized into control and endotoxin groups. The endotoxin group was injected with endotoxin at a dose of 10 mg/kg body wt. Hybridization of ET-1 and ETAR mRNA of the hepatic tissue was proceeded at 3, 6, 12 and 24 hours after endotoxin administration.. By in situ hybridization, the cell expression of ET-1 mRNA was hepatic sinusoids, the endothelial cells of portal vein, and Kupffer cell and the cell expression of ETAR mRNA was the small artery smooth muscle cells of hepatic lobule and the hepatic sinusoidal lining cells. The accumulation of grain was observed in many cells of the liver. The number of accumulating grain increased in unit scope.. ET-1 is synthesized by the hepatic sinusoids, hepatic vascular endothelial cells, and Kupffer cells, ETAR may be located on the hepatic vascular smooth muscle cells and Ito cells (fat-storing cells) around sinusoid. Endotoxin may, on transcription and translation level, lead to the increase of ET-1 and ETAR in synthesis and release.

Topics: Animals; Endothelin-1; Endothelium, Vascular; Endotoxemia; Hepatic Artery; In Situ Hybridization; Kupffer Cells; Liver; Muscle, Smooth, Vascular; Rats; Rats, Wistar; Receptor, Endothelin A; Receptors, Endothelin; RNA, Messenger

To study the effect of endotoxin on the alteration of the transcription, expression and cellular location of endothelin-1 (ET-1) mRNA in the hepatic tissue.. Wistar rats were divided into control and endotoxic group. The rats in the control group were injected with saline, and those in the endotoxic group with endotoxin at a dose of 10 mg.kg-1 body wt. ET-1 hepatic homogenate was assayed by radioimmunoassay at 3, 6, 9, 12 and 24 h after endotoxin administration. Dot blot was used to identify and quantify ET-1 mRNA of the hepatic tissue. Hybridization of ET-1 of the hepatic tissue was proceeded at 3, 6, 12 and 24 h after endotoxin administration.. ET-1 concentrations and the level of ET-1 mRNA increased rapidly and reached the peak at 6 h, and remained high at 24 h after endotoxin administration. By in situ hybridization, ET-1 mRNA was found in hepatic sinusoids, endothelial cells of portal vein and kupffer cells.. Endotoxin may be the principal stimulating factor for expression of ET-1 mRNA in hepatic tissue. Endotoxin may affect transcription and translation level of ET-1, leading to increase of the synthesis and release of ET-1. The hepatic vascular endothelial cells, hepatic sinusoids and Kupffer cells all synthesize and release ET-1.

Topics: Animals; Endothelin-1; Endotoxemia; Female; Kupffer Cells; Liver; Male; Rats; Rats, Wistar; RNA, Messenger