thromboxane-b2 and Endotoxemia

To evaluate the effect of IV administration of polymyxin B on clinical and serum biochemical variables in foals with experimental endotoxemia.. Prospective experimental study.. 14 healthy neonatal foals.. Foals were randomly assigned to a treatment or control group and were administered a single dose of lipopolysaccharide (0.5 μg/kg [0.23 μg/lb]) IV over 30 minutes. The treatment group received polymyxin B (6,000 U/kg [2,727 U/lb], IV) immediately after completion of lipopolysaccharide infusion; the control group was administered an equal volume of saline (0.9% NaCl) solution. Subsequent doses of polymyxin B or saline solution were administered IV at 8 and 16 hours. Blood was collected at various time points, and outcome variables, including heart rate, respiratory rate, rectal temperature, attitude score, WBC count, neutrophil count, lymphocyte count, monocyte count, platelet count, Hct, blood lactate concentration, blood glucose concentration, serum tumor necrosis factor-α concentration, and plasma thromboxane B2 concentration, were measured. Urine was collected prior to and after experimentation to determine whether nephrotoxicosis was associated with treatment.. The treatment group had significantly lower blood lactate concentration and serum tumor necrosis factor-α and plasma thromboxane B2 concentrations and had higher blood glucose concentrations and better attitude scores, compared with the control group, at various time points during the study. No other significant differences and no evidence of overt nephrotoxicosis were detected.. Administration of polymyxin B IV in healthy neonatal foals challenged with lipopolysaccharide attenuated some clinical and serum biochemical derangements associated with endotoxemia.

Topics: Administration, Intravenous; Animals; Animals, Newborn; Endotoxemia; Female; Horse Diseases; Horses; Lipopolysaccharides; Male; Polymyxin B; Thromboxane B2; Time Factors; Tumor Necrosis Factor-alpha

Acetylsalicylic acid (ASA) prevents thromboembolic events by inhibiting platelet function through blocking of cyclooxygenase type 1 (COX-1). A nitroderivate of ASA, 2-(acetyloxy)benzoic acid 3-(nitrooxymethyl)-phenyl ester (NCX 4016) was synthesized, which additionally acts through nitric oxide release. In various in vitro and animal studies NCX 4016 exhibited antithrombotic and anti-platelet properties. We used the standardized model of endotoxin infusion into human volunteers to compare the effects of NCX 4016 and ASA on platelet function and TF-induced coagulation activation. The trial consisted of two parts. In the first part, 10 healthy male volunteers were included in a randomized, open cross-over trial to find a NCX formulation with optimal tolerability and pharmacokinetic data were obtained. The second part was a randomized, double blind placebo controlled clinical trial consisting of 30 healthy male volunteers in three parallel groups (n = 10 per group). Volunteers received either NCX 4016 (800 mg b.i.d.), ASA (425 mg b.i.d.) or placebo for 7 days, before infusion of 2 ng/kg endotoxin on day 8. ASA attenuated the endotoxin-induced platelet plug formation (measured by PFA-100) significantly better than NCX 4016 and placebo (p < 0.004), while there was no difference in soluble P-selectin or VWF-levels. Urine 11-dehydro-thromboxane B(2) levels were significantly lower in the ASA and NCX 4016 groups as compared to placebo (p < 0.05). Neither ASA nor NCX 4016 significantly changed prothrombin fragment(1 + 2), D-Dimer or tissue factor (TF)-mRNA levels. In summary, NCX 4016 had no effect on VWF release, platelet activation as measured by soluble P-selectin or TF gene expression. NCX 4016, at the dose tested, unlike ASA, had no effect on platelet collagen/epinephrine induced plug formation under high shear rates.

Topics: Adult; Anti-Inflammatory Agents, Non-Steroidal; Aspirin; Blood Coagulation; Blood Platelets; Double-Blind Method; Endotoxemia; Endotoxins; Humans; Male; Platelet Activation; Thromboxane B2; Young Adult

The clinical and anti-inflammatory effects of a single treatment of 0.4 mg meloxicam/kg bodyweight on pigs that had been challenged with Escherichia coli endotoxin were investigated. Significantly lower total clinical scores were recorded in pigs treated with meloxicam than in pigs treated with a placebo. Significantly higher mean serum concentrations of thromboxane B(2) were also recorded in pigs treated with a placebo for up to 24 hours after the challenge. The serum concentrations of acute phase proteins and specific antibody titres to E coli lipopolysaccharide were unaffected by the meloxicam. The meloxicam treatment was well tolerated.

Topics: Acute-Phase Proteins; Animals; Anti-Inflammatory Agents, Non-Steroidal; Antibodies, Bacterial; Endotoxemia; Escherichia coli; Escherichia coli Infections; Female; Immunoglobulin G; Lipopolysaccharides; Male; Meloxicam; Single-Blind Method; Swine; Swine Diseases; Thiazines; Thiazoles; Thromboxane B2; Treatment Outcome

The effect of intravenous administration of lipid emulsions enriched with omega-3 (n3) and omega-6 (n6) fatty acids on equine monocyte phospholipid fatty acid composition and the synthesis of inflammatory mediators in vitro was evaluated. In a randomized crossover design, horses were infused intravenously with 20% lipid emulsions containing n3 or n6 fatty acids. Monocytes were isolated from the horses before and 0 h, 8 h, 24 h, and 7 days after lipid infusion. Monocyte fatty acid analysis demonstrated incorporation of the parenteral n3 and n6 fatty acids in monocyte phospholipids immediately after infusion, with changes in the fatty acid composition persisting for up to 7 days after infusion. In vitro production of the inflammatory mediators thromboxane B2/thromboxane B3 (TXB(2/3)) and tumor necrosis factor-alpha (TNFalpha) by peripheral blood monocytes was diminished by n3 lipid infusion and was unchanged or increased by n6 lipid infusion. The results of this study demonstrate that short-term infusions of n3 and n6 fatty acid-enriched lipid emulsions alter the fatty acid composition of equine monocyte phospholipids and modify the inflammatory response of these cells in vitro. These results also support further investigation into the use of parenteral n3 fatty acids as part of the supportive therapy of patients with multiple organ dysfunction (MODS) or systemic inflammatory response syndrome (SIRS).

Topics: Animals; Calcimycin; Cells, Cultured; Cross-Over Studies; Emulsions; Endotoxemia; Fatty Acids; Fatty Acids, Omega-3; Fatty Acids, Omega-6; Fatty Acids, Unsaturated; Female; Gene Expression Regulation; Horse Diseases; Horses; Infusions, Intravenous; Ionophores; Lipopolysaccharides; Male; Membrane Lipids; Monocytes; Phospholipids; Thromboxane B2; Thromboxanes; Tumor Necrosis Factor-alpha

Estradiol plus progesterone (EP) implants have been shown to favorably alter the time course or decrease the severity of many of the clinical manifestations associated with coccidiosis and endotoxemia in calves. This study evaluated the effect of EP treatment on plasma tumor necrosis factor-alpha (TNF), thromboxane (TXB), prostacyclin (PRC), nitrite and nitrate (NO[x]), and cortisol. Holstein steer calves were divided into four groups: control, EP, endotoxin (LPS), and EP + LPS (n = five/group). Estradiol/progesterone pellets (Synovex-S) were implanted subcutaneously when calves reached 20 wk of age. One week after implantation, calves were injected i.v. with endotoxin (i.e., lipopolysaccharide; LPS, 0.6 microgram/kg of BW) or nonpyrogenic saline placebo. Body temperature was measured and blood was collected before injection and at 1, 2, 3, 4, 6, and 8 h thereafter. Plasma concentrations of TNF, cortisol, TXB, PRC, NO[x], were measured. Body temperature increased in both LPS and LPS-EP calves, but had returned to normal by 6 h in the LPS-EP group (P < 0.05). Plasma TNF and cortisol increased after LPS (P < 0.01), but were not differentially affected by EP treatment. Likewise, EP did not affect the magnitude of increase in LPS-induced PRC, but EP decreased the magnitude of increase in TXB (P < 0.05). Plasma NO[x]) levels were increased (P < 0.01) in calves after LPS; treatment with EP attenuated the LPS-associated increase in plasma NO[x] levels. These results suggest that EP exerts specific effects on different components of the proinflammatory cytokine cascade. Although the initiation of responses mediated by TNF, cortisol, and PRC do not seem to be differentially affected by EP, components of the nitric oxide- and TXB-axis responses to LPS are decreased in calves pretreated with EP.

Topics: Animal Feed; Animals; Cattle; Cattle Diseases; Cytokines; Endotoxemia; Estradiol; Lipopolysaccharides; Male; Nitric Oxide; Progesterone; Random Allocation; Thromboxane B2; Tumor Necrosis Factor-alpha

We examined the effects of endogenous nitric oxide (NO) inhibition on the longitudinal distribution of pulmonary vascular resistance and on arachidonic acid metabolism during endotoxemia in awake sheep. Mean pulmonary artery (Ppa), left atrial (Pla), and systemic artery pressure (Psa) were continuously measured, and cardiac output (CO) was continuously monitored by an implanted ultrasonic flow probe. We advanced a 7-French Swan-Ganz catheter into distal pulmonary artery and measured the pulmonary microwedge pressure (Pmw) with the balloon deflated, allowing calculation of upstream pulmonary vascular resistance (PVRup = [Ppa - Pmw]/CO) and down-stream PVR (PVRdown = [Pmw - Pla]/CO), respectively. In paired studies, endotoxin (1 micro g/kg) was infused over 30 minutes with and without N(omega)-nitro-L-arginine (NLA) treatment. NLA (20 mg/kg) was administered 30 minutes before endotoxin infusion. Endotoxin caused increases in PVRup and PVRdown. Pretreatment with NLA increases PVRup at baseline and enhanced increases in both PVRup and PVRdown during endotoxemia. Plasma level of thromboxane B(2) (TxB(2)) and prostacyclin (6-keto = PGF(1alpha)) significantly increased 1 hour after endotoxin administration (TxB(2), 308.3 +/- 94.8 [SE] to 2163.5 +/- 988.5 pg ml(-1), P <.05; 6-keto=PGF(1alpha), 155.6 +/- 91.4 to 564.9 +/- 131.8 pg ml(-1), P <.05), but the increased levels were similar to those in the NLA-pretreated animals. We conclude that endogenous NO mainly regulates precapillary vascular tone at baseline, and that NO modulated pre- and postcapillary vascular constriction during endotoxemia in sheep. It appears that cyclooxygenase production in response to endotoxin is unaffected by NO and its vascular effects.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Endotoxemia; Enzyme Inhibitors; Hemodynamics; Nitric Oxide; Nitroarginine; Oxygen; Partial Pressure; Prostaglandins; Pulmonary Circulation; Sheep; Thromboxane B2; Vascular Resistance

We investigated the effect of mercaptoethylguanidine (MEG, 3 mg kg(-1)h(-1)), a combined selective inducible nitric oxide synthase (iNOS) inhibitor, a peroxynitrite and oxygen free radical scavenger with cyclooxygenase-inhibitor properties on intestinal and hepatic perfusion, O2 exchange, and metabolism during long-term hyperdynamic porcine endotoxemia. MEG was started 12 h after onset of endotoxemia. At baseline and after 12, 18, and 24 h of endotoxemia, hepatic arterial and portal venous blood flow, ileal mucosal-arterial PCO2 gap, portal and hepatic venous lactate/pyruvate ratio, free glutathione (GSH), and 8-isoprostanes were measured. Expired NO and plasma nitrate levels were assessed as well. MEG blunted the endotoxin-induced increase in expired NO and prevented the progressive fall in blood pressure without affecting cardiac output. It attenuated both systemic and regional venous acidosis without influencing the impairment of hepatosplanchnic metabolism nor counteracting the increase in GSH levels. In our model MEG failed to beneficially affect variables of oxidative stress.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Cardiac Output; Endotoxemia; Escherichia coli; Female; Glutathione; Hemodynamics; Hemoglobins; Lipopolysaccharides; Male; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Oxygen Consumption; Peroxynitrous Acid; Respiratory Mechanics; Swine; Thromboxane B2; Vascular Resistance

The aim of this clinical study was to investigate the time sequence between intraoperative and postoperative endotoxemia, changes in intramucosal pH(I), mediator release, and acute phase proteins and their relationship to postoperative infections. In 60 patients (median age 61 [33-72] years, male/female: 50/10) plasma levels of endotoxin, endotoxin neutralizing capacity (ENC), leukotriene-C4 (LTC4), 6-ketoprostaglandin-F-1alpha (PGF), thromboxane-B2 (TxB2), interleukin-6 (IL-6), and C-reactive protein (CRP) were measured before, during, and after cardiac surgery. The intraluminal pH(I) of the stomach was assessed as a marker of splanchnic blood circulation. Patients were divided in one group with postoperative infections (group A, n = 8) and another groups without infections (group B, n = 52). Among all measured parameters, endotoxin plasma levels showed the most rapid changes. A significant increase of endotoxin plasma levels and a decrease in ENC appeared after the induction of anesthesia, culminating in a peak after reperfusion. Endotoxin showed a significantly higher increase in group A (14fold) compared to group B (sixfold, p<0.001), whereas ENC decreased by eightfold in both groups. The parameters of the arachidonic cascade increased and pH(I) decreased, however, there were no significant differences between both groups. The latest increase was observed for the acute phase proteins IL-6 and CRP. IL-6 levels peaked 6 hours postoperatively with a 20fold (group B) and 30fold (group A) increase (p < 0.001 vs baseline; no differences between groups), whereas CRP rose at the first postoperative day with a 21 fold (group B) and 25fold (group A) increase at day 2 (p<0.001 vs baseline, no difference between groups). Differences between both groups appeared at the second postoperative day for IL-6 (median values group A/B: 421/219 pg/mL; p <0.05) and at the fifth postoperative day for CRP (median values group A/B: 321/81 mg/L; p < 0.05). In conclusion, endotoxin seems to be the earliest trigger of the mediator cascade in acute phase response and may indicate infections in the postoperative course.

Topics: Acute-Phase Proteins; Adult; Aged; Anesthesia; C-Reactive Protein; Cardiac Surgical Procedures; Endotoxemia; Endotoxins; Female; Humans; Hydrogen-Ion Concentration; Interleukin-6; Intestinal Mucosa; Intraoperative Period; Leukotriene C4; Male; Middle Aged; Postoperative Complications; Postoperative Period; Prostaglandins F; Thromboxane B2

In this study, gram-positive Staphylococcus aureus lipoteichoic acid (LTA) dose-dependently (0.1-1.0 microg/ml) and time-dependently (10-60 min) inhibited platelet aggregation in human platelets stimulated by agonists. LTA also dose-dependently inhibited phosphoinositide breakdown and intracellular Ca+2 mobilization in human platelets stimulated by collagen. LTA (0.5 and 1.0 microg/ml) also significantly inhibited thromboxane A2 formation stimulated by collagen in human platelets. Moreover, LTA (0.1-1.0 microg/ml) dose-dependently decreased the fluorescence of platelet membranes tagged with diphenylhexatrience. Rapid phosphorylation of a platelet protein of Mr. 47,000 (P47), a marker of protein kinase C activation, was triggered by PDBu (30 nM). This phosphorylation was markedly inhibited by LTA (0.5 and 1.0 microg/ml) within a 10-min incubation period. These results indicate that the antiplatelet activity of LTA may be involved in the following pathways: LTA's effects may initially be due to induction of conformational changes in the platelet membrane, leading to a change in the activity of phospholipase C, and subsequent inhibition of phosphoinositide breakdown and thromboxane A2 formation, thereby leading to inhibition of both intracellular Ca+2 mobilization and phosphorylation of P47 protein. Therefore, LTA-mediated alteration of platelet function may contribute to bleeding diathesis in gram-positive septicemic and endotoxemic patients.

Topics: Calcium Signaling; Cell Membrane; Collagen; Cytosol; Dose-Response Relationship, Drug; Endotoxemia; Enzyme Activation; Gram-Negative Bacterial Infections; Gram-Positive Bacterial Infections; Hemorrhagic Disorders; Humans; L-Lactate Dehydrogenase; Lipopolysaccharides; Membrane Fluidity; Membrane Lipids; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Peptides; Phorbol 12,13-Dibutyrate; Phosphatidylinositols; Phosphorylation; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Glycoprotein GPIIb-IIIa Complex; Protein Kinase C; Protein Processing, Post-Translational; Sepsis; Shock, Septic; Staphylococcus aureus; Teichoic Acids; Thromboxane A2; Thromboxane B2

Recently, eicosapentaenoic acid (EPA) was found to have an anti-inflammatory effect attributable to diminished synthesis of arachidonic acid metabolites that initiate acute lung injury. We evaluated the ability of dietary EPA supplementation to prevent endotoxin-induced acute lung injury in rats.. Rats fed a standard diet were divided randomly into two groups: for 2 weeks one group additionally was fed 1000 mg/kg/day of EPA ethyl ester emulsion (EPA rats), while in the other group the diet was supplemented with vehicle alone (control rats). Fatty acid components of alveolar macrophages (AM) were measured, as well as leukotriene (LT) B(4) and LTB(5) production by AM exposed in vitro to calcium ionophore A23187. Plasma concentrations of thromboxane (Tx) B(2), a stable metabolite of TxA(2), were examined 1 h after inducing lung injury with endotoxin (2 mg/kg iv). At 6 h, wet/dry (W/D) weight ratios were calculated for the lungs to assess pulmonary edema, and neutrophils were counted in pulmonary parenchyma and peripheral blood.. Arachidonic acid content and LTB(4) generation in AM were significantly lower in EPA rats than in controls; conversely, EPA content and LTB(5) generation in AM were significantly higher in the EPA group. Neutrophil counts in lung parenchyma and peripheral blood did not differ between groups, but W/D and plasma TxB(2) concentrations were significantly lower in EPA rats.. EPA supplementation depressed arachidonic acid content and LTB(4) generation in AM and plasma TxB(2) in our model, leading to decreased pulmonary edema.

Topics: Animals; Arachidonic Acid; Eicosapentaenoic Acid; Endotoxemia; Fatty Acids; Leukotriene B4; Male; Neutrophils; Pulmonary Edema; Rats; Rats, Wistar; Respiratory Distress Syndrome; Thromboxane B2

Ten horses were used in a crossover study to evaluate the effectiveness of eltenac against endotoxaemia. Eltenac (0.5 mg/kg bwt) or saline control was given i.v. then 15 min later, intravenous infusion of endotoxin was begun and continued for 120 min (total dose 100 ng/kg bwt). Horses were monitored for heart and respiratory rates, pulmonary and carotid arterial pressure and core body temperature. Blood was sampled at intervals for measurement of haematological variables and plasma concentrations of lactate, prostanoid metabolites, tumour necrosis factor (TNF) and stress hormones. In comparison with saline-treatment, use of eltenac significantly protected against endotoxin-induced changes in respiratory rate, core temperature, systemic arterial blood pressure (SAP), pulmonary arterial pressure, PCV, and plasma protein, 6-keto prostaglandin F1 alpha, thromboxane B2, epinephrine, and cortisol concentrations. Despite statistical effect of eltenac on SAP, values in both treatment groups remained well above baseline throughout the evaluation period. Significant protective effect of eltenac was not found for heart rate, white blood cell count, plasma lactate concentration or TNF activity. On the basis of these results, it is expected that use of eltenac will provide clinical benefit in horses with naturally occurring endotoxaemia.

Topics: Aniline Compounds; Animals; Anti-Inflammatory Agents, Non-Steroidal; Bacterial Toxins; Cross-Over Studies; Endotoxemia; Escherichia coli Infections; Horse Diseases; Horses; Injections, Intravenous; Plasma; Prostaglandins; Pulmonary Wedge Pressure; Random Allocation; Respiration; Thiophenes; Thromboxane B2

To determine the efficacy of polymyxin B-dextran 70 (PBD) for treatment of endotoxemic horses.. 15 horses during study 1 and 6 horses during study 2.. 3 groups were used in study 1. Horses in groups 1 and 2 were given 30 ng of lipopolysaccharide (LPS)/kg of body weight, IV, over 60 minutes. Horses in group 3 were given saline (0.9% NaCl) solution. Beginning 15 minutes before LPS infusion and continuing for 75 minutes, horses in groups 1 and 3 were given PBD, IV. Horses in group 2 were given dextran 70. Blood samples were obtained for hemograms and determination of cytokine, lactate, and prostanoid concentrations. In study 2, horses were given ketoprofen (2.2 mg/kg) or saline solution 15 minutes before infusion of PBD. Fourteen days later, treatments were reversed, using a crossover design. Blood samples were obtained for measurement of thromboxane B2 (TXB2) concentration.. For study 1, prior treatment with PBD completely blocked endotoxin-induced changes for heart and respiratory rates, rectal temperature, WBC count, and plasma tumor necrosis factor, interleukin 6, TXB2, and prostaglandin F1 concentrations. There was transient tachypnea, sweating, and increased plasma TXB2 concentration in horses given PBD (with or without LPS). Prior treatment with ketoprofen eliminated all PBD-induced signs and prevented the increase in plasma TXB2 concentration.. Signs of endotoxemia were prevented in horses by treatment with PBD, although its use was associated with mild adverse effects.. When used in combination with a cyclooxygenase-inhibiting drug, PBD has potential for treatment of horses with endotoxemia.

Topics: Animals; Anti-Bacterial Agents; Anticoagulants; Body Temperature; Cross-Over Studies; Cyclooxygenase Inhibitors; Dextrans; Drug Combinations; Endotoxemia; Female; Heart Rate; Hematocrit; Horse Diseases; Horses; Infusions, Intravenous; Interleukin-6; Ketoprofen; Leukocyte Count; Lipid A; Lipopolysaccharides; Male; Polymyxin B; Random Allocation; Thromboxane B2; Tumor Necrosis Factor-alpha

Ibuprofen, a cyclooxygenase inhibitor, improves pulmonary and cardiovascular injury in endotoxemia. We studied the mechanism of the beneficial effects of ibuprofen in relation to production of inflammatory mediators which influence vascular tone in endotoxemia. Rats were randomly assigned to one of three groups: (1) control, (2) endotoxemia alone; and (3) ibuprofen pretreatment and endotoxemia. Plasma and lung lavage concentrations of tumor necrosis factor, thromboxane B2 (TXB2), leukotriene (LT) C4,D4,E4 and nitric oxide (NO) were determined over a 2 h period. Pretreatment with ibuprofen resulted in increased survival, and attenuation of pulmonary and cardiovascular dysfunction when compared to the rats receiving endotoxin alone. The marked elevation in plasma TXB2 concentration in endotoxemic rats was prevented by pretreatment with ibuprofen. Similarly, pretreatment with ibuprofen prevented the decrease in lung lavage NO levels in endotoxemic rats. The improved survival and cardiopulmonary protection in endotoxemic rats pretreated with ibuprofen appears to be related to decreased thromboxane production and preservation of endothelial production of nitric oxide.

Topics: Animals; Blood Pressure; Cardiovascular System; Cyclooxygenase Inhibitors; Endotoxemia; Ibuprofen; Leukotrienes; Lung; Nitric Oxide; Rats; Thromboxane B2; Vasoconstriction

BMS182874, an endothelin receptor antagonist, blocks the effects of exogenously administered endothelins in chronically instrumented awake sheep. A possible role for endothelin in endotoxin-induced pulmonary hypertension in sheep was investigated by studying animals given intravenous endotoxin with and without pretreatment with BMS182874. BMS182874 administration alone caused a reduction in pulmonary artery pressure (P[PA]) and systemic arterial pressure (P[SA]). Endotoxin alone caused an acute, nearly threefold increase in P(PA) which was followed, from 2-5 h after endotoxin, by a sustained but less severe increase in P(PA). These changes were accompanied by a threefold increase in lung lymph flow and dramatic increases in plasma and lung lymph thromboxane B2 concentrations. Pretreatment with BMS182874 significantly attenuated the early endotoxin-induced acute increase in P(PA) and completely blocked the late sustained pulmonary hypertension (p < 0.05), while having no affect on the increases in thromboxane levels. BMS182874 shifts the dose response curve for U46619, a prostaglandin H2 analogue, to the right. BMS182874, in addition to functioning as an endothelium receptor antagonist, appears to counteract the action of thromboxane at the receptor level. We theorize that BMS182874 attenuates the early endotoxin-induced pulmonary hypertension by counteracting the effects of thromboxane, since previous studies demonstrated that the early acute rise in P(PA) is caused by thromboxane. The late sustained pulmonary hypertension of endotoxemia, on the other hand, appears to be mediated by endothelin.

Topics: Animals; Antihypertensive Agents; Dansyl Compounds; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Endothelin Receptor Antagonists; Endothelins; Endotoxemia; Female; Hypertension, Pulmonary; Lymph; Male; Premedication; Pulmonary Wedge Pressure; Sheep; Thromboxane B2

Tumor necrosis factor alpha (TNF-alpha) activity, platelet and neutrophil degranulation and margination, and increased vascular permeability are central to the pathophysiology of endotoxin-mediated acute lung injury. Nonanticoagulant activities of low molecular weight heparin (LMWH) include solubilization of the TNF-alpha receptor protein, inhibition of neutrophil adhesion, and regulation of thromboxane B2 (TXB2) biosynthesis. In this study, we evaluated the ability of LMWH to modulate TNF-alpha and TXB2 activity during endotoxemia and the subsequent effects on pulmonary hemodynamics. Domestic pigs 8-10 weeks old were anesthetized and catheterized for standard cardiopulmonary measurements and the lungs harvested for cuff:vessel ratio, myeloperoxidase activity, and permeability index. Pigs were randomly assigned to one of four groups: lipopolysaccharide (LPS) (n = 6), given .5 microg/kg/h Escherichia coli LPS intravenously for 6 h; saline control (n = 5); LMWH (n = 5), given .5 mg/kg LMWH for 30 min, followed by .5 mg/kg/h; and LMWH + LPS (same dosages, n = 6). Administration of LPS resulted in increased plasma TNF-alpha and TXB2 activity; increased pulmonary arterial pressure, pulmonary vascular resistance, and alveolar-arterial oxygen tension; decreased systemic arterial oxygen tension; and pulmonary edema. The cardiopulmonary parameters for the LMWH-treated pigs did not differ from those of the saline-treated control pigs. Pretreatment with LMWH attenuated the LPS-mediated TNF-alpha and TXB2 activity and attenuated LPS-mediated pulmonary hypertension, hypoxemia and neutrophil emigration, and edema formation. In conclusion, the data show that the protective effects of LMWH in this model of acute lung injury are associated with altered neutrophil adhesion and TNF-alpha and thromboxane activity.

Topics: Animals; Blood Platelets; Blood Pressure; Cell Adhesion; Endotoxemia; Endotoxins; Escherichia coli; Hemodynamics; Hemostasis; Heparin, Low-Molecular-Weight; Leukocyte Count; Lipopolysaccharides; Lung; Lung Injury; Neutrophils; Peroxidase; Pulmonary Circulation; Swine; Thromboxane B2; Tumor Necrosis Factor-alpha; Vascular Resistance

The interaction between constitutive nitric oxide and oxygen may depend on the degree of tissue oxygenation and may play a critical role in the pathophysiological response to endotoxaemia. We investigated if hyperoxia (100% O2) attenuated the systemic and pulmonary vasoconstriction and increased biosynthesis of thromboxane B2 (TXB2) and 6-keto-prostaglandin (PG) F1alpha induced by inhibition of nitric oxide synthase with NG-nitro-L-arginine-methyl-ester (L-NAME) in a porcine model of endotoxaemia. Twenty-two domestic, random source pigs, weighing 15.4 +/- 2.7 kg (mean +/- standard deviation) were the subjects of this study. Pigs were anaesthetized with isoflurane in 100% O2, orotracheally intubated and ventilated to maintain normocapnia, and then instrumented for haemodynamic monitoring. Following instrumentation, pigs were maintained at an end-tidal isoflurane concentration of 2%. Pigs were randomly assigned to treatment groups: saline + 30% O2 (Control, n = 6); Escherichia coli lipopolysaccharide (5 microg/kg/h from 1 to 2 h followed by 2 microg/kg/h from 2 to 5 h) + 30% O2 (LPS, n = 4); L-NAME (0.5 mg/kg/h, from 0 to 5 h) + LPS + 100% O2 (n = 6); and L-NAME + LPS + 30% O2 (n = 6). L-NAME and endotoxin significantly (P < 0.05) increased mean arterial pressure, mean pulmonary arterial pressure, and systemic and pulmonary vascular resistance index beginning at 90 min. When results were pooled across all time periods, mean arterial pressure and mean pulmonary arterial pressure were significantly higher in the L-NAME + LPS + 30% O2 group than all other groups, reflecting pulmonary and systemic vasoconstriction. Hyperoxia attenuated the L-NAME + LPS-induced increases in TXB2 and 6-keto-PGF1alpha concentrations at 90 and 120 min and 120 min, respectively, although the differences were not statistically significant. These results support the observation that nitric oxide synthase inhibition with L-NAME has deleterious haemodynamic effects in this model of endotoxaemia. The temporal attenuation of L-NAME-induced pulmonary and systemic vasoconstriction by hyperoxia suggested that the haemodynamic effects of acute endotoxaemia were in part influenced by the relative amounts of nitric oxide and oxygen present.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Endotoxemia; Enzyme Inhibitors; Escherichia coli Infections; Hemodynamics; Hyperoxia; Lung; NG-Nitroarginine Methyl Ester; Nitric Oxide Synthase; Pulmonary Circulation; Swine; Swine Diseases; Thromboxane B2; Vasoconstriction

Inflammatory stimuli and lipid peroxidation up-regulate cyclooxygenase (COX)-2. This study evaluated the relationship between inflammatory mediators, COX expression, and pathological changes in experimental alcoholic liver disease.. Rats (5 per group) were fed ethanol and a diet containing saturated fat, corn oil, or fish oil by intragastric infusion. Dextrose isocalorically replaced ethanol in controls. In the first set of experiments, whole livers were analyzed. In the second set of experiments, Kupffer cells, endothelial cells, and hepatocytes were isolated from rats in each group. Pathological analyses and measurements of lipid peroxidation, tumor necrosis factor (TNF)-alpha, COX-1 and COX-2 messenger RNA (mRNA), endotoxin, and liver and plasma thromboxane were performed.. Increased expression of COX-2 mRNA was detected in the livers of rats showing necroinflammatory changes. The Kupffer cell was the cell primarily responsible for the increase in COX-2 mRNA level. Increased expression of COX-2 was associated with increased levels of endotoxin, TNF-alpha mRNA, lipid peroxidation, and synthesis of thromboxane. COX-1 mRNA was decreased in Kupffer cells in rats with the most severe liver injury.. Up-regulation of COX-2 in alcoholic liver injury occurred in the presence of proinflammatory stimuli and resulted in increased synthesis of inflammatory and vasoactive eicosanoids. Down-regulation of COX-1 may result in decreased synthesis of cytoprotective eicosanoids and additionally exacerbate liver injury.

Topics: Animals; Cyclooxygenase 2; Endotoxemia; Gene Expression Regulation, Enzymologic; Isoenzymes; Kupffer Cells; Lipid Peroxidation; Liver Diseases, Alcoholic; Male; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Wistar; RNA, Messenger; Thromboxane B2; Tumor Necrosis Factor-alpha

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

To determine if inhibition of nitric oxide synthase with NG-nitro-L-arginine-methyl-ester (L-NAME) potentiates endotoxin-induced cardiopulmonary dysfunction and release of cyclooxygenase products in a porcine model of endotoxemia.. Prospective, multiple group, controlled experimental study.. Physiologic research laboratory at a veterinary medicine college.. Fifty-seven domestic pigs (mean 28.7 +/- 0.8 [SEM] kg).. Pentobarbital-anesthetized pigs were intubated and mechanically ventilated to normocapnia with room air. A ther-modilution cardiac output catheter was advanced into the pulmonary artery. Additional catheters were inserted into the jugular and femoral veins and femoral artery. The pigs received the following infusions: saline (control, n = 5); L-NAME (0.1, 0.5, 2.2, or 5.5 mg/ kg/hr, from -0.5 to 2 hrs, n = 16); Escherichia coli endotoxin (5 micrograms/ kg from 0 to 1 hr followed by 2 micrograms/kg from 1 to 2 hrs, i.v., n = 14); L-NAME plus endotoxin (n = 9); indomethacin plus endotoxin (n = 6); or L-NAME indomethacin plus endotoxin (n = 7).. L-NAME significantly (p < .05) worsened endotoxin-induced hypoxemia and enhanced the increases in pulmonary vascular resistance index and systemic vascular resistance index at 30 to 60 mins. Endotoxin increased (p < .05) plasma concentrations of thromboxane B2 by seven- to eight-fold at 30 to 120 mins and 6-keto-prostaglandin F1 alpha by 16- to 24-fold at 60 to 120 mins. L-NAME enhanced (additive effect) endotoxin-induced increases in plasma concentrations of thromboxane B2 (60 mins) and significantly (p < .05) potentiated the increases in 6-keto-prostaglandin F1 alpha (120 mins). At 120 mins of endotoxemia, indomethacin (cyclooxygenase inhibitor) plus L-NAME markedly increased (p < .05, synergistic effect) systemic vascular resistance index compared with endotoxemic pigs pretreated with either L-NAME or indomethacin.. During endotoxemia, inhibition of nitric oxide synthase with L-NAME may be deleterious to cardiopulmonary function, as evidence by potentiation of endotoxin-induced systemic and pulmonary vasoconstriction, impairment of gas exchange, and enhanced biosynthesis of cyclooxygenase products. Moreover, during endotoxemia, the concomitant inhibition of two important vasodilators (i.e., nitric oxide and prostacyclin) is associated with a potentiated (p < .05) increase in systemic vascular resistance index.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Cyclooxygenase Inhibitors; Endotoxemia; Heart; Indomethacin; Lung; NG-Nitroarginine Methyl Ester; Nitric Oxide Synthase; Prospective Studies; Swine; Thromboxane B2; Vascular Resistance; Vasoconstriction

To compare effects of a single dose of pentoxifylline (PTX), flunixin meglumine (FM), and their combination (FM/PTX) in a model of equine endotoxemia.. 24 healthy horses, aged 2 to 15 years.. 4 groups (n = 6/group) received 30 ng of Escherichia coli O55:B5 endotoxin/kg of body weight, i.v., over 30 minutes, and 1 of the following preparations 15 minutes before and 8 hours after endotoxin infusion: FM, 1.1 mg/kg; PTX, 8 mg/kg; FM/PTX, 1.1 mg of FM and 8 mg of PTX/kg; and saline solution bolus (ENDO). Clinical and hematologic variables were measured over 24 hours.. Compared with ENDO, FM given before endotoxin significantly reduced TxB2, and 6-keto-PGF1 concentrations, pulse, rectal temperature, and attitude score. Pentoxifylline given before endotoxin resulted in significantly higher 6-keto-PGF1 concentration at 1.5 hours and significantly lower PAI-1 activity at 12 hours. Tumor necrosis factor and IL-6 activities in horses given PTX alone were not significantly different from values in those given the saline bolus. FM/PTX induced effects similar to those of FM alone on endotoxin-induced changes in temperature and TxB2 concentration, and 6-keto-PGF1 concentration was significantly lower than that in horses of the ENDO group at 1 hour. In horses of the FM group, 6-keto-PGF1 concentration was significantly lower than that in horses of the ENDO group, from 0.5 hour to 2 hours. Horses of the FM and FM/PTX groups had significantly higher IL-6 activity at 1.5 and 2 hours than did horses of the PTX and ENDO groups; those of the FM and FM/PTX groups had significantly lower WBC count than did those of the PTX and ENDO groups.. FM/PTX may help offset deleterious hemodynamic effects of endotoxin more effectively than does either FM or PTX alone.

Topics: 6-Ketoprostaglandin F1 alpha; Analysis of Variance; Animals; Anti-Inflammatory Agents, Non-Steroidal; Body Temperature; Clonixin; Disease Models, Animal; Drug Combinations; Endotoxemia; Escherichia coli; Escherichia coli Infections; Hemodynamics; Horse Diseases; Horses; Interleukin-6; Leukocyte Count; Pentoxifylline; Plasminogen Activator Inhibitor 1; Thromboxane B2; Time Factors; Tissue Plasminogen Activator; Tumor Necrosis Factor-alpha; Vasodilator Agents

To evaluate the effect of pentoxifylline on response of horses to in vivo challenge exposure with endotoxin.. 24 healthy horses in 3 treatment groups: pentoxifylline, endotoxin, or endotoxin and pentoxifylline.. Horses of the pentoxifylline group were given a bolus of pentoxifylline (7.5 mg/kg of body weight, i.v.), followed by an infusion (3 mg/kg/h) over 3 hours, and those of the endotoxin group were given 20 ng of endotoxin/kg i.v. over 30 minutes. Those of the combination group were given both of the aforementioned compounds; pentoxifylline was administered immediately after endotoxin. Clinical (rectal temperature, heart and respiratory rates, blood pressure) and hematologic (WBC count; whole blood recalcification time; plasma fibrinogen, thromboxane B2, and 6-keto-prostaglandin F1 alpha concentrations; plasma plasminogen activator inhibitor activity; and serum tumor necrosis factor and interleukin 6 activities) variables were evaluated over 24 hours.. Compared with baseline values, there were no significant changes in any variable over time in the horses receiving only pentoxifylline, with the exception of a significant increase in WBC count. Rectal temperature, heart rate, mean blood pressure, WBC count, whole blood recalcification time, fibrinogen concentration, plasminogen activator inhibitor activity, tumor necrosis factor and interleukin 6 activities, and plasma thromboxane B2 concentration changed significantly over time in horses of the endotoxin and endotoxin-pentoxifylline combination groups. Respiratory rate and plasma 6-keto-prostaglandin F1 alpha concentration changed significantly over time only in horses of the endotoxin group. Compared with values for the endotoxin group, rectal temperature and respiratory rate were significantly lower, and whole blood recalcification time was longer for the endotoxin/pentoxifylline group.. Beneficial effects of pentoxifylline are limited when it is administered i.v. to horses after in vivo challenge exposure with endotoxin.

Topics: 6-Ketoprostaglandin F1 alpha; Analysis of Variance; Animals; Blood Pressure; Body Temperature; Disease Models, Animal; Endotoxemia; Endotoxins; Fibrinogen; Heart Rate; Horse Diseases; Horses; Infusions, Intravenous; Interleukin-6; Leukocyte Count; Pentoxifylline; Plasminogen Inactivators; Respiration; Thromboxane B2; Tumor Necrosis Factor-alpha; Vasodilator Agents

Septic shock is associated with high mortality despite the development of new antibiotics. Since Vitamin A has an immunomodulating ability and is able to lower the concentrations of endotoxin and some cytokines, we decided to study whether supplementation with vitamin A may have a beneficial effect in experimental endotoxaemia.. A porcine model was used, in which normally bred (i.e., not vitamin A depleted) animals were anaesthetised, monitored and injected intramuscularly with a non-toxic dose of vitamin A (230 IU.kg-1) (n = 9) or the corresponding volume of vehicle (n = 9) 1 hour before an infusion of purified E. coli endotoxin was given in a dose of 10 micrograms.kg-1.h-1 over 6 hours. Another 3 pigs also injected with vitamin A, but not endotoxin, served as controls.. Vitamin A- and endotoxin-injected pigs were significantly less affected in several circulatory and respiratory variables as compared to vehicle-and endotoxin-injected animals (e.g., blood pressure; heart rate; cardiac index; pulmonary capillary wedge pressure; left and right ventricular stroke work indices; pH; base excess; oxygen delivery; and oxygen extraction). Vitamin A did not per se significantly affect these variables. Hb increased significantly in the vehicle group, indicating a more pronounced capillary permeability. Urinary output or fluid supply did not differ between the groups. Myocardial production of metabolites of prostacyclin or thromboxane A2 did not differ between the groups.. Pre-treatment with vitamin A had a beneficial effect on several variables, such as oxygen delivery and metabolic acidosis in the endotoxaemic pig. Improvement of these variables is associated with increased survival in septic shock and may indicate reduced tissue hypoxia. Thus, vitamin A may turn out to be useful as a prophylactic agent in conditions where septic shock is apt to occur.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Endotoxemia; Hemodynamics; Hemoglobins; Myocardium; Oxygen; Oxygen Consumption; Premedication; Pulmonary Wedge Pressure; Respiratory Mechanics; Swine; Thromboxane B2; Vitamin A

The manipulation of stress gene expression by heavy metals provides protection against the lethal effects of endotoxemia in murine models of septic shock. Recent in vitro studies with alveolar macrophages or monocytes show that induction of the stress response in these cells is followed by a decreased liberation of major cytokines [tumor necrosis factor-alpha (TNF alpha) and interleukin-1 (IL-1)] after endotoxin challenge. These findings suggest that the increased resistance to endotoxin in vivo after stress protein induction could be explained by an altered pattern of inflammatory mediator release. Therefore, we measured the time course of thromboxane-B2 (TxB2), 6-keto-PGF1 alpha, platelet activating factor (PAF), TNF alpha, interleukin-1 beta (IL-1 beta), and interleukin-6 (IL-6) formation with and without induction of the stress response in an established porcine model of recurrent endotoxemia (Klosterhalfen et al., Biochem Pharmacol 43: 2103-2109, 1992). Induction of the stress response was done by a pretreatment with Zn2+ (25 mg/kg zinc-bis-(DL-hydrogenasparate = 5 mg/kg Zn2+). Pretreatment with Zn2+ prior to lipopolysaccharide (LPS) infusion induced an increased heat shock protein 70 and metallothionein expression in the lungs, liver, and kidneys and increased plasma levels of TNF alpha, IL-1 beta, IL-6, and TxB2 as opposed to untreated controls. After LPS infusion, however, pretreated animals showed significantly decreased peak plasma levels of all mediators as opposed to the untreated group. The time course of mediator release was identical with the decreasing and increasing three peak profiles described previously. Hemodynamic data presented significantly decreased peak pulmonary artery pressures and significantly altered hypodynamic/hyperdynamic cardiac output levels in the pretreated group. In conclusion, the data show that the induction of stress proteins by Zn2+ could be a practicable strategy to prevent sepsis.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Aspartic Acid; Blood Pressure; Cardiac Output; Disease Models, Animal; Endotoxemia; Gene Expression; HSP70 Heat-Shock Proteins; Inflammation Mediators; Interleukin-1; Interleukin-6; Kidney; Lipopolysaccharides; Metallothionein; Platelet Activating Factor; Pulmonary Artery; Recurrence; Swine; Thromboxane B2; Tumor Necrosis Factor-alpha; Zinc