thromboxane-a2 and Disease-Models--Animal

A confluence of technological advances in genetic manipulation and molecular-based fluorescence imaging has led to the widespread adoption of laser injury models to study hemostasis and thrombosis in mice. In all animal models of hemostasis and thrombosis, detailing the nature of experimentally induced vascular injury is paramount in enabling appropriate interpretation of experimental results. A careful appraisal of the literature shows that direct laser-induced injury can result in variable degrees of vascular damage. This review will compare and contrast models of laser injury utilized in the field, with an emphasis on the mechanism and extent of injury, the use of laser injury in different vascular beds and the molecular mechanisms regulating the response to injury. All of these topics will be discussed in the context of how distinct applications of laser injury models may be viewed as representing thrombosis and/or hemostasis.

Topics: Animals; Disease Models, Animal; Endothelial Cells; Femoral Artery; Hemostasis; Humans; Intravital Microscopy; Laser Therapy; Mice; Platelet Activation; Saphenous Vein; Thrombosis; Thromboxane A2; Vascular System Injuries

Abdominal aortic aneurysm (AAA) is one of the leading causes of death in western countries. Surgery is still, at the present time, the sole treatment that has however a significant mortality and cost rate. Many pharmacological agents are under investigation aiming to reduce growth and prevent AAA rupture. These drugs target different pathological pathways and, notably, the excessive production of prostanoids by cyclooxygenases (COX). Intra-aneurysmal thrombus plays an adverse key role in the progression of AAA, platelets being a primary source of prostanoids as thromboxane A2.. In this review, we summarize studies targeting prostanoids production and down-stream pathways in cardiovascular diseases, and more specifically in AAA.. Various inhibitors of COX or antagonists of prostanoids receptors have been investigated in AAA animal models with conflicting results. In human AAA, only a few number of studies focused on anti-platelet therapy mostly using acetylsalicylic acid (aspirin, ASA), a COX1 inhibitor. Finally, we report preliminary promising results of a model of AAA in rats receiving a thromboxane A2 inhibitor, BM-573 that induced a reduction of aneurysmal growth.

Topics: Animals; Aortic Aneurysm, Abdominal; Cyclooxygenase Inhibitors; Disease Models, Animal; Humans; Prostaglandin Antagonists; Prostaglandins; Rats; Sulfonylurea Compounds; Thromboxane A2

Platelets play a central role in inflammation through their direct interaction with other cell types, such as leucocytes and endothelial cells, and by the release of many factors, that is, lipids [such as thromboxane (TX)A2 ] and proteins (a wide number of angiogenic and growth factors) stored in α-granules, and adenosine diphosphate (ADP), stored in dense granules. These platelet actions trigger autocrine and paracrine activation processes that lead to leucocyte recruitment into different tissues and phenotypic changes in stromal cells which contribute to the development of different disease states, such as atherosclerosis and atherothrombosis, intestinal inflammation and cancer. The signals induced by platelets may cause pro-inflammatory and malignant phenotypes in other cells through the persistent induction of aberrant expression of cyclooxygenase (COX)-2 and increased generation of prostanoids, mainly prostaglandin (PG)E2 . In addition to cardiovascular disease, enhanced platelet activation has been detected in inflammatory disease and intestinal tumourigenesis. Moreover, the results of clinical studies have shown that the antiplatelet drug aspirin reduces the incidence of vascular events and colorectal cancer. All these pieces of evidence support the notion that colorectal cancer and atherothrombosis may share a common mechanism of disease, that is, platelet activation in response to epithelial (in tumourigenesis) and endothelial (in tumourigenesis and atherothrombosis) injury. Extensive translational medicine research is necessary to obtain a definitive mechanistic demonstration of the platelet-mediated hypothesis of colon tumourigenesis. The results of these studies will be fundamental to support the clinical decision to recommend the use of low-dose aspirin, and possibly other antiplatelet agents, in primary prevention, that is, even for individuals at low cardiovascular risk.

Topics: Animals; Aspirin; Blood Platelets; Cardiovascular Diseases; Colorectal Neoplasms; Cyclooxygenase 2; Disease Models, Animal; Endothelial Cells; Humans; Inflammation; Leukocytes; Neoplasms; Platelet Activation; Platelet Aggregation Inhibitors; Stromal Cells; Thromboxane A2; Up-Regulation

The neonatal rat is born with its eyes closed and an immature visual system, that some say is equivalent to that of a human fetus at 26 weeks of gestation. From birth, the visual system of the newborn rat will gradually mature, the first manifestation of that being the opening of the eye which usually take place at postnatal day 14. Complete maturation of the retina and visual pathways is normally reached at the end of the first month of life. The neonatal rat model thus represents a unique paradigm to study the normal and abnormal maturation of the primary visual pathways that normally occurs in utero in human subjects. Our laboratory has, over the past decade, developed two animal models of postnatally induced retinopathy, namely the Oxygen-Induced Retinopathy (OIR) that share several common features with the human Retinopathy of Prematurity (ROP) and the Light-Induced Retinopathy that is viewed by some as a valid model of some forms of Retinitis Pigmentosa (RP). The following pages review what is known of the pathophysiological processes taking place and suggest possible therapeutic avenues that could be explored in order to halt the degenerative process.

Topics: Animals; Animals, Newborn; Disease Models, Animal; Fetal Development; Humans; Infant, Newborn; Isoprostanes; Light; Oxygen; Platelet Activating Factor; Rats; Retina; Retinitis Pigmentosa; Retinopathy of Prematurity; Thromboxane A2; Visual Pathways

The purpose of this review is to summarize the role of prostaglandins (PGs) in allergic inflammation and to know the value of PGs, as a target molecule for an anti-allergic drug. PGD(2) is the major PG produced by the cyclooxygenase pathway in mast cells. Our and others findings indicate that PGD(2) is one of the potent allergic inflammatory mediators and must be a target molecule of anti-allergic agent. From our data, one of PGD(2) receptor antagonists show clear inhibition of airway hypersensitivity caused by allergic reaction. Concerning the role of PGE(2) in allergic inflammation, conflicting results have been reported. Many experimental data suggest an individual role of each PGE(2) receptor, EP(1), EP(2), EP(3) and EP(4) in allergic reaction. Our results indicate the protective action of PGE(2) on allergic reaction via EP(3). In addition, one of EP(3) agonists clearly inhibits the allergic airway inflammation. These findings indicate the value of EP(3) agonists as an anti-allergic agent. In addition, some investigators including us reported that PGI(2) plays an important role for the protection of the onset of allergic reaction. However, the efficacy of PGI(2) analogue as an anti-allergic agent is not yet fully investigated. Finally, the role of thromboxane A(2) (TxA(2)) in allergic reaction is discussed. Our experimental results suggest a different participation of TxA(2) in allergic reaction of airway and skin. In this review, the role of PGs in allergic inflammation is summarized and the value of PGs as a target molecule for developing a new anti-allergic agent will be discussed.

Topics: Animals; Anti-Allergic Agents; Bronchial Provocation Tests; Disease Models, Animal; Humans; Hypersensitivity; Mice; Prostaglandins; Receptors, Immunologic; Receptors, Prostaglandin; Receptors, Prostaglandin E; Receptors, Prostaglandin E, EP3 Subtype; Thromboxane A2

Historically, anti-inflammatory drugs had their origins in the serendipitous discovery of certain plants and their extracts being applied for the relief of pain, fever and inflammation. When salicylates were discovered in the mid-19th century to be the active components of Willow Spp., this enabled these compounds to be synthesized and from this, acetyl-salicylic acid or Aspirin was developed. Likewise, the chemical advances of the 19th-20th centuries lead to development of the non-steroidal anti-inflammatory drugs (NSAIDs), most of which were initially organic acids, but later non-acidic compounds were discovered. There were two periods of NSAID drug discovery post-World War 2, the period up to the 1970's which was the pre-prostaglandin period and thereafter up to the latter part of the last century in which their effects on prostaglandin production formed part of the screening in the drug-discovery process. Those drugs developed up to the 1980-late 90's were largely discovered empirically following screening for anti-inflammatory, analgesic and antipyretic activities in laboratory animal models. Some were successfully developed that showed low incidence of gastro-intestinal (GI) side effects (the principal adverse reaction seen with NSAIDs) than seen with their predecessors (e.g. aspirin, indomethacin, phenylbutazone); the GI reactions being detected and screened out in animal assays. In the 1990's an important discovery was made from elegant molecular and cellular biological studies that there are two cyclo-oxygenase (COX) enzyme systems controlling the production of prostanoids [prostaglandins (PGs) and thromboxane (TxA2)]; COX-1 that produces PGs and TxA2 that regulate gastrointestinal, renal, vascular and other physiological functions, and COX-2 that regulates production of PGs involved in inflammation, pain and fever. The stage was set in the 1990's for the discovery and development of drugs to selectively control COX-2 and spare the COX-1 that is central to physiological processes whose inhibition was considered a major factor in development of adverse reactions, including those in the GI tract. At the turn of this century, there was enormous commercial development following the introduction of two new highly selective COX-2 inhibitors, known as coxibs (celecoxib and rofecoxib) which were claimed to have low GI side effects. While found to have fulfilled these aims in part, an alarming turn of events took place in the late 2004 period when rofecox

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Cardiovascular Diseases; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cytokines; Digestive System Diseases; Disease Models, Animal; Drug Delivery Systems; Drug Design; Fever; History, 19th Century; History, 20th Century; History, 21st Century; Humans; Inflammation; Isoenzymes; Neoplasms; Neurodegenerative Diseases; Pain; Prostaglandins; Signal Transduction; Stroke; Thromboxane A2

The use of antiplatelet agents in chronic glomerular disease is reviewed, with emphasis on drugs affecting thromboxane A2 synthesis or action. The results of short-term and long-term studies in human as well as animal models suggest a role for enhanced intrarenal synthesis of thromboxane A2, though not clearly defining the potential platelet vs glomerular targets of drug action. The availability of novel inhibitors and antagonists may provide new therapeutic strategies against thromboxane-A2-dependent loss of renal function.

Topics: Animals; Disease Models, Animal; Glomerulonephritis; Humans; Platelet Aggregation Inhibitors; Thromboxane A2

Evidence that combined thromboxane A2 and serotonin blockade may prevent coronary artery thrombosis and the conversion from chronic to acute coronary heart disease syndromes is considered. Available data from clinical and experimental animal studies are consistent with the hypothesis that interference with thromboxane and serotonin's contributions to platelet aggregation and dynamic coronary artery constriction might prevent the conversion from chronic to acute disorders, including the development of unstable angina and myocardial infarction in some patients at risk. Substantial protection preventing the conversion from stable to unstable angina and myocardial infarction may very well require both thromboxane and serotonin receptor antagonists or the combination of a thromboxane synthesis inhibitor and receptor antagonist with a serotonin receptor antagonist. Future clinical studies should test this hypothesis directly.

Topics: Animals; Coronary Disease; Disease Models, Animal; Humans; Serotonin Antagonists; Thrombosis; Thromboxane A2

Topics: Animals; Disease Models, Animal; Glomerulonephritis; Lupus Nephritis; Rats; Thromboxane A2

Topics: Animals; Arteries; Blood Vessel Prosthesis; Disease Models, Animal; Epoprostenol; Lymphedema; Microcirculation; Microsurgery; Musculoskeletal System; Research; Surgical Flaps; Thromboxane A2; Ultrasonics; Veins

Topics: Angina Pectoris; Animals; Arachidonic Acids; Coronary Circulation; Coronary Disease; Coronary Vessels; Disease Models, Animal; Epoprostenol; Humans; Leukocytes; Lipoxygenase; Myocardial Infarction; Prostaglandin-Endoperoxide Synthases; Prostaglandins; Thromboxane A2

Barrett's esophagus (BE), a complication of gastroesophageal reflux disease (GERD), predisposes patients to esophageal adenocarcinoma (EAC). Reliable biomarkers for early detection and discovery of potential drug targets are urgently needed for improved BE and EAC patient outcomes.. Patient biopsy samples were evaluated for COX1/2, and thromboxane A2 synthase (TBXAS) expression. Circulating prostaglandins biosynthesis was determined using enzyme immunoassay kits. Anchorage-independent cell growth assay, crystal violet staining assay, and xenograft experiments were conducted to assess BE and EAC cell growth. A surgical mouse model of reflux (i.e., esophagoduodenostomy) was established and samples were analyzed using an enzyme immunoassay kit, immunohistochemistry, immunoblotting, or RT-PCR. Esophageal biopsy samples (pre- and post-intervention) were obtained from a randomized clinical trial in which participants were administered esomeprazole (40 mg) twice daily in combination with an acetylsalicylic acid (ASA) placebo or 81 or 325 mg ASA for 28 days. Esophageal biopsy specimens before and after the intervention period were analyzed.. COX2 and TBXAS are highly expressed in BE and EAC patients accompanied by a pronounced elevation of circulating TXA2 levels. ASA suppressed BE and EAC growth by targeting the TXA2 pathway. Additionally, biopsies from 49 patients (with similar baseline characteristics) showed that ASA substantially decreased serum TXA2 levels, resulting in reduced inflammation.. This study establishes the importance of the COX1/2-driven TXA2 pathway in BE and EAC pathophysiology and lays the groundwork for introducing a TXA2-targeting strategy for EAC prevention and early detection.. Hormel Foundation, Exact Sciences, Pentax Medical, Intromedic and National Cancer.

Topics: Adenocarcinoma; Animals; Aspirin; Barrett Esophagus; Carcinogenesis; Cell Line, Tumor; Cell Proliferation; Cyclooxygenase 1; Cyclooxygenase 2; Disease Models, Animal; Esophageal Neoplasms; Extracellular Signal-Regulated MAP Kinases; Female; Humans; Inflammation; Male; Mice, Inbred C57BL; Middle Aged; Molecular Targeted Therapy; Signal Transduction; STAT3 Transcription Factor; Thromboxane A2

Aside from the established immune-mediated etiology of multiple sclerosis (MS), compelling evidence implicates platelets as important players in disease pathogenesis. Specifically, numerous studies have highlighted that activated platelets promote the central nervous system (CNS)-directed adaptive immune response early in the disease course. Platelets, therefore, present a novel opportunity for modulating the neuroinflammatory process that characterizes MS. We hypothesized that the well-known antiplatelet agent acetylsalicylic acid (ASA) could inhibit neuroinflammation by affecting platelets if applied at low-dose and investigated its effect during experimental autoimmune encephalomyelitis (EAE) as a model to study MS. We found that oral administration of low-dose ASA alleviates symptoms of EAE accompanied by reduced inflammatory infiltrates and less extensive demyelination. Remarkably, the percentage of CNS-infiltrated CD4

Topics: Animals; Aspirin; Blood Platelets; Brain; CD4-Positive T-Lymphocytes; Disease Models, Animal; Dose-Response Relationship, Drug; Encephalomyelitis, Autoimmune, Experimental; Inflammation; Mice, Inbred C57BL; Multiple Sclerosis; Platelet Aggregation Inhibitors; Thromboxane A2

[Figure: see text].

Topics: Animals; Cells, Cultured; Diaphragm; Disease Models, Animal; Humans; Inflammation; Lipopolysaccharides; Lymphangiogenesis; Lymphatic Vessels; Macrophages, Peritoneal; Male; Mice, Inbred C57BL; Mice, Knockout; Receptors, Thromboxane A2, Prostaglandin H2; Signal Transduction; T-Lymphocytes; Thromboxane A2; Vascular Endothelial Growth Factor C; Vascular Endothelial Growth Factor D

The protective effect of aspirin against myocardial hypertrophy (MH) was studied. Model rats of pressure overload MH were prepared by abdominal aortic coarctation. Rats were randomly divided into the sham group (

Topics: Animals; Apoptosis; Aspirin; Blood Pressure; Body Weight; Cardiotonic Agents; Disease Models, Animal; Fibrillar Collagens; Heart Ventricles; Hypertrophy; Inflammation Mediators; Interleukin-10; Male; Myocardium; Myocytes, Cardiac; Organ Size; Prostaglandins; Rats, Wistar; Thromboxane A2; Tumor Necrosis Factor-alpha

Topics: Adult; Animals; Antifibrotic Agents; Antihypertensive Agents; Aspirin; Biomarkers; Blood Platelets; Blood Pressure; Cardiomyopathies; Case-Control Studies; Cells, Cultured; Disease Models, Animal; Essential Hypertension; Female; Fibrosis; Humans; Male; Mice, Inbred C57BL; Mice, Knockout; Middle Aged; Myocytes, Cardiac; Myofibroblasts; Platelet Aggregation Inhibitors; Receptors, Epoprostenol; Receptors, Thromboxane; Thromboxane A2

Hypertension is one of the most common complications of chronic kidney disease (CKD). Some research has indicated that changes in large artery function especially caused by thromboxane A2 (TXA2) may be a novel factor acting to induce hypertension in CKD. We studied the 5/6 nephrectomy rat model and measured serum levels of creatinine (Cr), calcium (Ca), phosphorus (P), TXA2-stable metabolites (thromboxane B2, TXB2), and caudal artery pressure after nephrectomy. The tension variations in thoracic aortas were measured after stimulating by vasoconstrictor/vasodilator using the cumulative concentration administration method and then tested the expression of TXA2 receptors in the thoracic aortas through western blots. The CKD rats developed uremia, electrolyte imbalances，and hypertension. They also exhibited a significant increase in TXB2 concentration. The aortic rings of CKD rats showed an increased contraction response to U46619 (a TXA2 analogue) and the expression of TXA2 receptors also enhanced. In the meanwhile, the diastolic function decreased in the CKD group. Our results demonstrate that the impairment of artery contractile function caused by the increase of TXA2 receptors on the wall of aortic rings may be involved in hypertension in CKD rats.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Aorta, Thoracic; Disease Models, Animal; Humans; Hypertension; Male; Rats; Receptors, Thromboxane; Renal Insufficiency, Chronic; Thromboxane A2; Vasoconstriction; Vasoconstrictor Agents

Aspirin eugenol ester (AEE) is a novel compound that is formed from the esterification of aspirin (acetylsalicylic acid (ASA)) and eugenol. This study aimed to investigate the effects of AEE on blood stasis in rats and to characterize the underlying mechanisms using a plasma metabolomic study. The results indicate that AEE and ASA could modulate whole blood viscosity (WBV), plasma viscosity (PV), blood coagulation parameters, platelet count, platelet aggregation, lactate dehydrogenase (LDH), creatinine (CR) and the levels of thromboxane A2 (TXA

Topics: Animals; Aspirin; Blood; Blood Chemical Analysis; Blood Coagulation; Blood Viscosity; Chromatography, High Pressure Liquid; Disease Models, Animal; Epoprostenol; Eugenol; Female; Hematologic Diseases; Metabolomics; Platelet Aggregation; Rats; Thromboxane A2

2-Arachidonoylglycerol (2-AG) is a major modulator of blood flow and platelet aggregation and a potential neuroprotectant. The present study investigated, for the first time, the effects of 2-AG on cerebral blood flow (CBF) in the first critical hours during middle cerebral artery occlusion (MCAO) and on platelet aggregation in rats. Adult male Sprague-Dawley rats ( n = 30) underwent permanent MCAO under isoflurane anesthesia and were randomly assigned to receive either 2-AG (6 mg/kg iv), monoacylglycerol lipase inhibitor JZL-184 (10 mg/kg iv), or vehicle ( n = 6 rats/group) treatment. CBF and cardiovascular responses were measured, by a blinded investigator, for up to 4 h. In separate experiments, platelet aggregation by 2-AG (19-300 µM) was assessed by whole blood aggregometry ( n = 40). 2-AG and JZL-184 significantly increased the severity of the CBF deficit versus vehicle (20.2 ± 8.8% and 22.7 ± 6.4% vs. 56.4 ± 12.1% of pre-MCAO baseline, respectively, P < 0.05) but had no effect on blood pressure or heart rate. While JZL-184 significantly increased the number of thrombi after MCAO, this did not reach significance by 2-AG. 2-AG induced platelet aggregation in rat whole blood in a similar manner to arachidonic acid and was significantly reduced by the cyclooxygenase inhibitors indomethacin and flurbiprofen and the thromboxane receptor antagonist ICI 192,605 ( P < 0.05). This is the first study showing that 2-AG increases the severity of the CBF deficit during MCAO, and further interrogation confirmed 2-AG-induced platelet aggregation in rats. These findings are important because 2-AG had previously been shown to exert neuroprotective actions and therefore force us to reevaluate the circumstances under which 2-AG is beneficial. NEW & NOTEWORTHY 2-Arachidonoylglycerol (2-AG) has neuroprotective properties; however, the present study revealed that 2-AG increases the severity of the cerebral blood flow deficit during middle cerebral artery occlusion in rats. Further interrogation showed that 2-AG induces platelet aggregation in rats. These findings force us to reevaluate the circumstances under which 2-AG is beneficial.

Topics: Animals; Arachidonic Acids; Blood Platelets; Cerebrovascular Circulation; Disease Models, Animal; Endocannabinoids; Glycerides; Infarction, Middle Cerebral Artery; Male; Neuroprotective Agents; Platelet Aggregation; Prostaglandin-Endoperoxide Synthases; Rats, Sprague-Dawley; Severity of Illness Index; Thromboxane A2; Time Factors

Hypertensive disease of pregnancy (HDP) with placental insufficiency is the most common cause of fetal growth restriction (FGR) in the developed world. Despite the known negative consequences of HDP both to the mother and fetus, little is known about the longitudinal placental changes that occur as HDP progresses in pregnancy. This is because longitudinal sampling of human placentae during each gestation is impossible. Therefore, using a mouse model of thromboxane A2-analog infusion to mimic human HDP in the last trimester, we calculated placental efficiencies based on fetal and placental weights; quantified spongiotrophoblast and labyrinth thicknesses and vascular density within these layers; examined whether hypoxia signaling pathway involving vascular endothelial growth factor A (VEGFA) and its receptors (VEGFR1, VEGFR2) and matrix metalloproteinases (MMPs) contributed to vascular change; and examined nutrient transporter abundance including glucose transporters 1 and 3 (GLUT1, GLUT3), neutral amino acid transporters 1, 2, and 4 (SNAT1, SNAT2, and SNAT4), fatty acid transporters 2 and 4 (FATP2, FATP4), and fatty acid translocase (CD36) from embryonic day 15.5 to 19 in a 20-day C57Bl/6J mouse gestation. We conclude that early-to-mid gestation hypertensive placentae show compensatory mechanisms to preserve fetal growth by increasing placental efficiencies and maintaining abundance of important nutrient transporters. As placental vascular network diminishes over late hypertension, placental efficiency diminishes and fetal growth fails. Neither hypoxia signaling pathway nor MMPs mediated the vascular diminution in this model. Hypertensive placentae surprisingly exhibit a sex-differential expression of nutrient transporters in late gestation despite showing fetal growth failure in both sexes.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Amino Acid Transport Systems, Neutral; Animals; Disease Models, Animal; Fatty Acid Transport Proteins; Female; Fetal Growth Retardation; Glucose Transport Proteins, Facilitative; Matrix Metalloproteinases; Mice; Placenta; Placentation; Pregnancy; Signal Transduction; Thromboxane A2; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-1; Vascular Endothelial Growth Factor Receptor-2

To investigate the influence of dexmedetomidine on myocardial ischemia-reperfusion injury (IRI) in rabbits.. Twenty-four New Zealand white rabbits were randomly divided into two equal-sized groups: IRI group (group IR) and dexmedetomidine group (group D). Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), left ventricular diastolic pressure (LVDP), +dp/dtmax, -dp/dtmax, and t-dp/dtmax were recorded and calculated at the following time points: before (T0) and after (T1) dexmedetomidine infusion, after 30-min ischemia (T2), and after 120-min reperfusion (T3). The levels of plasma endothelin 1 (ET-1), thromboxane A2 (TXA2), and platelet activating factor (PAF); area of myocardial infarction (MI); and no-reflow area were evaluated.. SBP, DBP, LVSP, LVEDP, LVDP, and +dp/dtmax at T3 were higher in group D than in group IR (P<0.05). The average no-reflow area in group IR was significantly smaller than that in group D (14±3% vs. 38±5%, P=0.0116). The ET-1, TXA2, and PAF levels at T2 and T3 were higher than those at T0 in both groups (P<0.05).. Dexmedetomidine could reduce the magnitude of ischemic myocardial no-reflow area and protect the myocardium with ischemia-reperfusion injury.

Topics: Adrenergic alpha-2 Receptor Agonists; Animals; Dexmedetomidine; Disease Models, Animal; Endothelin-1; Heart Rate; Hemodynamics; Male; Myocardial Reperfusion Injury; No-Reflow Phenomenon; Platelet Activating Factor; Rabbits; Random Allocation; Reference Values; Reproducibility of Results; Thromboxane A2; Treatment Outcome

Topics: Animals; Dermatitis; Disease Models, Animal; Humans; Imiquimod; Interleukin-17; Mice; Mice, Inbred C57BL; Mice, Knockout; Psoriasis; Receptors, Antigen, T-Cell, gamma-delta; Receptors, G-Protein-Coupled; Receptors, Thromboxane A2, Prostaglandin H2; T-Lymphocytes; Thromboxane A2; Thromboxane-A Synthase

Non-alcoholic fatty liver disease (NAFLD) is now a public health issue worldwide, but no drug has yet received approval. Genistein, an isoflavonoid derived from soybean, ameliorates high-fat-diet-induced NAFLD in mice, but the molecular underpinnings remain largely elusive. Arachidonic acid (AA) is a major ingredient of animal fats, and the AA cascade has been implicated in chronic inflammation. In this study, we investigated whether genistein was against NAFLD by targeting the AA cascade. Using a mouse model, we showed that genistein supplementation improved high-fat-diet-induced NAFLD by normalizing hepatomegaly, liver steatosis, aminotransferase abnormalities, and glucose tolerance. The thromboxane A

Topics: Animals; Aspirin; Cyclooxygenase Inhibitors; Diet, High-Fat; Disease Models, Animal; Disease Progression; Genistein; Hep G2 Cells; Humans; Liver; Male; Mice; Mice, Inbred C57BL; Non-alcoholic Fatty Liver Disease; Receptors, Thromboxane A2, Prostaglandin H2; Thromboxane A2

Topics: Animals; Atorvastatin; Biomarkers; Disease Models, Animal; Epoprostenol; Hemodynamics; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Male; Metabolic Syndrome; Microcirculation; Microvessels; Models, Cardiovascular; Muscle, Skeletal; Nitric Oxide; Oxygen Consumption; Peripheral Vascular Diseases; Physical Conditioning, Animal; Physical Exertion; Rats, Zucker; Regional Blood Flow; Running; Thromboxane A2; Time Factors

We studied the relationship between 3-phosphoinositide-dependent protein kinase 1 (PDK1) and contractions induced by serotonin, phenylephrine, and thromboxane A

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; 3-Phosphoinositide-Dependent Protein Kinases; Animals; Carotid Arteries; Chronic Disease; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Disease Models, Animal; Indazoles; Male; Nitric Oxide; Nitric Oxide Synthase; Phenylephrine; Pyrimidines; Rats; Rats, Wistar; Serotonin; Signal Transduction; Thromboxane A2; Vasoconstriction; Vasoconstrictor Agents

Previous studies have shown that receptor-interacting protein kinase 3 (RIP3) is involved in many important biological processes, including necroptosis, apoptosis, and inflammation. Here we show that RIP3 plays a critical role in regulating platelet functions and in vivo thrombosis and hemostasis. Tail bleeding times were significantly longer in

Topics: Adenosine Diphosphate; Animals; Blood Platelets; Disease Models, Animal; Gene Expression; Hemostasis; Humans; Mice; Mice, Knockout; Phosphatidylserines; Phosphorylation; Platelet Activation; Platelet Aggregation; Proto-Oncogene Proteins c-akt; Receptor-Interacting Protein Serine-Threonine Kinases; Signal Transduction; Thrombin; Thrombosis; Thromboxane A2

ESSENTIALS: The role of ATP-binding cassette transporter 1 (ABCA1) in platelet functions is poorly characterized. We studied the impact of ABCA1 deficiency on platelet responses in a mouse model and two Tangier patients. ABCA1-deficient platelets exhibit reduced positive feedback loop mechanisms. This reduced reactivity is dependent on external environment and independent of hematopoietic ABCA1.. The ATP-binding cassette transporter ABCA1 is required for the conversion of apolipoprotein A-1 to high-density lipoprotein (HDL), and its defect causes Tangier disease, a rare disorder characterized by an absence of HDL and accumulation of cholesterol in peripheral tissues. The role of ABCA1 in platelet functions remains poorly characterized.. To determine the role of ABCA1 in platelet functions and to clarify controversies concerning its implication in processes as fundamental as platelet phosphatidylserine exposure and control of platelet membrane lipid composition.. We studied the impact of ABCA1 deficiency on platelet responses in a mouse model and in two Tangier patients. We show that platelets in ABCA1-deficient mice are slightly larger in size and exhibit aggregation and secretion defects in response to low concentrations of thrombin and collagen. These platelets have normal cholesterol and major phospholipid composition, granule morphology, or calcium-induced phosphatidylserine exposure. Interestingly, ABCA1-deficient platelets display a reduction in positive feedback loop mechanisms, particularly in thromboxane A2 (TXA2) production. Hematopoietic chimera mice demonstrated that defective eicosanoids production, particularly TXA2, was primarily dependent on external environment and not on the hematopoietic ABCA1. Decreased aggregation and production of TXA2 and eicosanoids were also observed in platelets from Tangier patients.. Absence of ABCA1 and low HDL level induce reduction of platelet reactivity by decreasing positive feedback loops, particularly TXA2 production through a hematopoietic ABCA1-independent mechanism.

Topics: Animals; ATP Binding Cassette Transporter 1; Blood Platelets; Cell Size; Disease Models, Animal; Feedback, Physiological; Female; Genetic Predisposition to Disease; Hematopoietic Stem Cell Transplantation; Hematopoietic Stem Cells; Hemostasis; Humans; Lipoproteins, HDL; Male; Mice, Inbred DBA; Mice, Knockout; Middle Aged; Phenotype; Platelet Aggregation; Tangier Disease; Thrombosis; Thromboxane A2; Time Factors

Dipeptidyl peptidase-4 (DPP4) is a key protein in glucose homeostasis and a pharmacological target in type 2 diabetes mellitus. This study explored whether the novel adipokine soluble DPP4 (sDPP4) can cause endothelial dysfunction, an early marker of impaired vascular reactivity.. Reactivity was studied in mesenteric arteries from 3-month-old female mice, using a small vessel myograph. Thromboxane A2 (TXA2) release was explored in cultured human coronary artery endothelial cells by enzyme immunoassay.. Neither the contractility to noradrenaline nor the endothelium-independent relaxations induced by sodium nitroprusside were modified by sDPP4. However, sDPP4 impaired in a concentration-dependent manner the endothelium-dependent relaxation elicited by acetylcholine. The DPP4 inhibitors K579 and linagliptin prevented the defective relaxation induced by sDPP4, as did the protease-activated receptor 2 (PAR2) inhibitor GB83. Downstream of PAR2, the cyclooxygenase (COX) inhibitor indomethacin, the COX2 inhibitor celecoxib or the thromboxane receptors blocker SQ29548 prevented the deleterious effects of sDPP4. Accordingly, sDPP4 triggered the release of TXA2 by endothelial cells, whereas TXA2 release was prevented by inhibiting DPP4, PAR2 or COX.. In summary, these findings reveal sDPP4 as a direct mediator of endothelial dysfunction, acting through PAR2 activation and the release of vasoconstrictor prostanoids. By interfering with these actions, DPP4 inhibitors might help preserving endothelial function in the context of cardiometabolic diseases.

Topics: Animals; Diabetes Mellitus, Type 2; Dipeptidyl Peptidase 4; Disease Models, Animal; Endothelial Cells; Endothelium, Vascular; Female; Mesenteric Arteries; Mice; Mice, Inbred C57BL; Receptor, PAR-2; Thromboxane A2

Thromboxane (Tx) A2 has been suggested to be involved in the development of sepsis-induced acute kidney injury (AKI). Therefore, we investigated the impact of cyclooxygenase (COX)-1 and COX-2 activity on lipopolysaccharide (LPS)-induced renal TxA2 formation, and on endotoxemia-induced AKI in mice. Injection of LPS (3 mg/kg ip) decreased glomerular filtration rate (GFR) and the amount of thrombocytes to ∼50% of basal values after 4 h. Plasma and renocortical tissue levels of TxB2 were increased ∼10- and 1.7-fold in response to LPS, respectively. The COX-1 inhibitor SC-560 attenuated the LPS-induced fall in GFR and in platelet count to ∼75% of basal levels. Furthermore, SC-560 abolished the increase in plasma and renocortical tissue levels of TxB2 in response to LPS. The COX-2 inhibitor SC-236 further enhanced the LPS-induced decrease in GFR to ∼40% of basal values. SC-236 did not alter thrombocyte levels nor the LPS-induced increase in plasma and renocortical tissue levels of TxB2. Pretreatment with clopidogrel inhibited the LPS-induced drop in thrombocyte count, but did not attenuate the LPS-induced decrease in GFR and the increase in plasma TxB2 levels. This study demonstrates that endotoxemia-induced TxA2 formation depends on the activity of COX-1. Our study further indicates that the COX-1 inhibitor SC-560 has a protective effect on the decrease in renal function in response to endotoxin. Therefore, our data support a role for TxA2 in the development of AKI in response to LPS.

Topics: Acute Kidney Injury; Animals; Blood Platelets; Cyclooxygenase 1; Cyclooxygenase 2 Inhibitors; Disease Models, Animal; Down-Regulation; Endotoxemia; Endotoxins; Glomerular Filtration Rate; Kidney; Male; Membrane Proteins; Mice, Inbred C57BL; Platelet Aggregation Inhibitors; Pyrazoles; Signal Transduction; Thromboxane A2; Time Factors

Platelets are known to play a crucial role in hemostasis. Sphingosine kinases (Sphk) 1 and 2 catalyze the conversion of sphingosine to the bioactive metabolite sphingosine 1-phosphate (S1P). Although platelets are able to secrete S1P on activation, little is known about a potential intrinsic effect of S1P on platelet function.. To investigate the role of Sphk1- and Sphk2-derived S1P in the regulation of platelet function.. We found a 100-fold reduction in intracellular S1P levels in platelets derived from Sphk2(-/-) mutants compared with Sphk1(-/-) or wild-type mice, as analyzed by mass spectrometry. Sphk2(-/-) platelets also failed to secrete S1P on stimulation. Blood from Sphk2-deficient mice showed decreased aggregation after protease-activated receptor 4-peptide and adenosine diphosphate stimulation in vitro, as assessed by whole blood impedance aggregometry. We revealed that S1P controls platelet aggregation via the sphingosine 1-phosphate receptor 1 through modulation of protease-activated receptor 4-peptide and adenosine diphosphate-induced platelet activation. Finally, we show by intravital microscopy that defective platelet aggregation in Sphk2-deficient mice translates into reduced arterial thrombus stability in vivo.. We demonstrate that Sphk2 is the major Sphk isoform responsible for the generation of S1P in platelets and plays a pivotal intrinsic role in the control of platelet activation. Correspondingly, Sphk2-deficient mice are protected from arterial thrombosis after vascular injury, but have normal bleeding times. Targeting this pathway could therefore present a new therapeutic strategy to prevent thrombosis.

Topics: Animals; Arachidonic Acid; Blood Coagulation; Blood Coagulation Tests; Blood Platelets; Carotid Artery Injuries; Disease Models, Animal; Erythrocytes; Lysophospholipids; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Knockout; Phosphotransferases (Alcohol Group Acceptor); Platelet Adhesiveness; Platelet Aggregation; Platelet Function Tests; Receptors, Lysosphingolipid; Signal Transduction; Sphingosine; Sphingosine-1-Phosphate Receptors; Thrombosis; Thromboxane A2; Vascular System Injuries

Reduction of Sheng-Nao-Kang decoction (RSNK), composed of Salvia miltiorrhiza Bge., Ligusticum chuanxiong Hort., Astragalus membranaceus (Fisch.) Bunge., Pueraria lobata (Willd.) Ohwi., Paeonia lactiflora Pall. and Panax notoginseng (Burk.) F. H. Chen., is a modified traditional Chinese medicinal formula of Sheng-Nao-Kang pill preparation, which has been investigated its protective effect on focal cerebral ischemia-reperfusion injury in rat in our previous report.. To evaluate the antithrombotic effect of RSNK in blood stasis model rats and explore the potential mechanisms.. Subcutaneous injection of norepinephrine and bovine serum albumin combined with ice water bath was used to establish the acute blood stasis rat model. The anticoagulant activities were investigated by measuring activated partial thromboplastin time (APTT), thrombin time (TT), prothrombin time (PT), and the content of fibrinogen (FIB). Meanwhile, the levels of thromboxane A2 (TXA2), prostaglandins I2 (PGI2), endothelial nitric oxide synthase (eNOS) and endothelin (ET) were detected.. The treatment of RSNK was able to prolong APTT, TT and PT, and decrease FIB content obviously. Furthermore, it markedly suppressed TXB2 level and up-regulated 6-keto-PGF1α level of the blood-stasis model rats, accompanied with the decrease of T/K. The level of ET and TXA2 in plasma was down-regulated and the levels of eNOS in plasma and PGI2 in serum was up-regulated in RSNK-treated rats compared with model rats (P<0.05).. The present study suggested that RSNK possessed remarkable antithrombotic property in blood stasis model rats induced by ice water bath and subcutaneous injection of norepinephrine and bovine serum albumin. This property could be associated with its anticoagulation activity, the regulation of active substances in vascular endothelium and maintaining the balance of TXA2 and PGI2.

Topics: 6-Ketoprostaglandin F1 alpha; Abietanes; Animals; Anticoagulants; Blood Coagulation; Blood Coagulation Tests; Caffeic Acids; Carotid Arteries; Catechols; Cold Temperature; Disease Models, Animal; Drugs, Chinese Herbal; Endothelins; Male; Nitric Oxide Synthase Type III; Norepinephrine; Phytotherapy; Rats, Sprague-Dawley; Serum Albumin, Bovine; Thrombosis; Thromboxane A2

Senile plaques comprised of Aβ peptides are a hallmark of Alzheimer's disease (AD) brain, as are activated glia that release inflammatory molecules, including eicosanoids. Previous studies have demonstrated that amyloid precursor protein (APP) and Aβ levels can be increased through activation of thromboxane A2-prostanoid (TP) receptors on neurons. We demonstrate that TP receptor regulation of APP expression depends on Gαq-signaling and conventional protein kinase C isoforms. Importantly, we discovered that Gαq-linked prostaglandin E2 and leukotriene D4 receptors also regulate APP expression. Prostaglandin E2 and thromboxane A2, as well as total APP levels, were found to be elevated in the brains of aged 5XFAD transgenic mice harboring Aβ plaques and activated glia, suggesting that increased APP expression resulted from eicosanoid binding to Gαq-linked neuronal receptors. Notably, inhibition of eicosanoid synthesis significantly lowered brain APP protein levels in aged 5XFAD mice. These results provide new insights into potential AD therapeutic strategies.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Animals; Brain; Cells, Cultured; Dinoprostone; Disease Models, Animal; Eicosanoids; Female; Gene Expression; GTP-Binding Protein alpha Subunits, Gq-G11; HEK293 Cells; Humans; Immunoblotting; Inflammation Mediators; Male; Mice, Transgenic; Neurons; Protein Kinase C; Rats; Receptors, Thromboxane A2, Prostaglandin H2; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Thromboxane A2

Dysregulation of the thromboxane A₂ (TP) receptor, resulting in agonist hypersensitivity and hyper-responsiveness, contributes to exaggerated vasoconstriction in the hypoxic pulmonary artery in neonatal persistent pulmonary hypertension. We previously reported that hypoxia inhibits TP receptor phosphorylation, causing desensitization. Hence, we examined the role of PKA-accessible serine residues in determining TP receptor affinity, using site-directed mutational analysis.. Vasoconstriction to a thromboxane mimetic and phosphorylation of TP receptor serine was examined in pulmonary arteries from neonatal swine with persistent pulmonary hypertension and controls. Effects of hypoxia were determined in porcine and human TP receptors. Human TPα serines at positions 324, 329 and 331 (C-terminal tail) were mutated to alanine and transiently expressed in HEK293T cells. Saturation binding and displacement kinetics of a TP antagonist and agonist were determined in porcine TP, wild-type human TPα and all TP mutants. Agonist-elicited calcium mobilization was determined for each TP mutant, in the presence of a PKA activator or inhibitor, and in hypoxic and normoxic conditions.. The Ser324A mutant was insensitive to PKA activation and hypoxia, had a high affinity for agonist and increased agonist-induced calcium mobilization. Ser329A was no different from wild-type TP receptors. Ser331A was insensitive to hypoxia and PKA with a decreased agonist-mediated response.. In hypoxic pulmonary hypertension, loss of site-specific phosphorylation of the TP receptor causes agonist hyper-responsiveness. Ser324 is the primary residue phosphorylated by PKA, which regulates TP receptor-agonist interactions. Ser331 mutation confers loss of TP receptor-agonist interaction, regardless of PKA activity.

Topics: Amino Acid Substitution; Animals; Animals, Newborn; Calcium Signaling; Cell Hypoxia; Cells, Cultured; Cyclic AMP-Dependent Protein Kinases; Disease Models, Animal; Enzyme Activators; HEK293 Cells; Humans; Mutagenesis, Site-Directed; Mutant Proteins; Myocytes, Smooth Muscle; Persistent Fetal Circulation Syndrome; Phosphorylation; Protein Kinase Inhibitors; Protein Processing, Post-Translational; Pulmonary Artery; Receptors, Thromboxane A2, Prostaglandin H2; Recombinant Proteins; Serine; Specific Pathogen-Free Organisms; Sus scrofa; Thromboxane A2

The Wistar-Furth (WF) rat strain is usually used in models of full major histocompatibility complex-mismatched kidney transplantation. Because these rats have been demonstrated to be resistant to several models of chronic kidney disease, the aim of the present study was to investigate their potential resistance to renal ischaemia-reperfusion (I/R) injury compared with another strain, namely Wistar-Hanover (WH) rats. Anaesthetized male WH and WF rats were submitted to I/R by occlusion of the left renal artery and contralateral nephrectomy. Urine, blood and tissue samples were collected at different time points after I/R to evaluate renal function, inflammation and tubular injury, along with determination of nitric oxide synthase (NOS) expression and thromboxane A2 (TxA2 ) production. Post-ischaemic renal function was better preserved in WF than WH rats, as evidenced by reduced levels of creatininaemia, urinary neutrophil gelatinase-associated lipocalin excretion and proteinuria. In addition, WF rats had less intrarenal inflammation than WH rats after I/R injury. These observations were associated with maintenance of neuronal NOS expression, along with lower induction of inducible NOS expression in WF versus WH rats. Moreover, WF rats excreted a significantly lower amount of TxB2 . The results indicate that WF rats are more resistant to an I/R injury than WH rats in terms of renal function and inflammation. These observations are associated with differential regulation of intrarenal NOS expression, as well as a reduction in thromboxane production, which could contribute to a better outcome for the postischaemic kidney in WF rats.

Topics: Acute Disease; Animals; Dinoprostone; Disease Models, Animal; Kidney; Kidney Function Tests; Male; Nitric Oxide; Nitric Oxide Synthase; Oxidative Stress; Rats, Inbred WF; Real-Time Polymerase Chain Reaction; Reperfusion Injury; Reverse Transcriptase Polymerase Chain Reaction; Thromboxane A2; Thromboxane B2

Danshensu, a type of dihydroxyphenyl lactic acid, is one of the most abundant active phenolic acids in the dried root of Salvia miltiorrhizae (Lamiaceae)--widely used traditional Chinese medicine. The effects of danshensu on platelet aggregation and thrombus formation in rats were examined using various methods. It was found that danshensu significantly reduced thrombus weight in 2 experimental thrombosis models; dose-dependent inhibition of adenosine diphosphate (ADP) and arachidonic acid (AA)-induced platelet aggregation occurred in normal and blood stasis-induced rats; Danshensu also significantly mitigated blood viscosity, plasma viscosity and hematocrit levels. Moreover, danshensu significantly inhibited venous thrombosis-induced expression of cyclooxygenases-2 (COX-2) rather than cyclooxygenases-1(COX-1) in the venous walls, down regulated thromboxane B2 (TXB2) and up regulated 6-keto prostaglandin F1α (6-keto-PGF1α), normalizing the TXB2/6-keto-PGF1α ratio. In addition, danshensu did not induce gastric lesions and even had protective effects on aspirin-induced ulcer formation at doses as high as 60 mg/kg. These findings suggest that the antithrombotic and antiplatelet aggregation effects of danshensu are attributed to its highly selective inhibition of COX-2 and ability to normalize the thromboxane A2(TXA2)/prostacyclin(PGI2) balance. These findings suggest that danshensu have great prospects in antithrombotic and antiplatelet therapy.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Cyclooxygenase 1; Cyclooxygenase 2; Disease Models, Animal; Lactates; Platelet Aggregation; Rats; Thromboxane A2; Thromboxane B2; Venous Thrombosis

Airway obstruction after antigen challenge is not always observed in patients with allergic asthma, even if they develop hyperresponsiveness. A similar event is observed in our guinea pig model of allergic asthma. Our aim was to study this phenomenon.. Sensitized guinea pigs were challenged with ovalbumin (OVA) 3 times every 10 days. Animals were divided into 2 groups: (1) Guinea pigs exhibiting airway obstruction after antigen challenge (R = responders), and (2) guinea pigs lacking airway obstruction response (NR = nonresponders). After the third antigen challenge, antigen-induced airway hyperresponsiveness (AI-AHR), serum OVA-specific immunoglobulins, bronchoalveolar lavage fluid (BALF) inflammatory cells, histamine, cysteinyl leukotrienes and thromboxane A2 (TxA2) BALF levels, and in vitro tracheal contraction induced by contractile mediators and OVA were evaluated.. R group consistently displayed a transient antigen-induced airway obstruction (AI-AO) as well as AI-AHR, high T×A2, histamine, OVA-IgG1, OVA-IgE and OVA-IgA levels, and intense granulocyte infiltration. NR group displayed no AI-AO and no changes in BALF measurements; nevertheless, AI-AHR and elevated OVA-IgG1 and OVA-IgA levels were observed. In all groups, histamine, TxA2 and leukotriene D4 induced a similar contraction. Tracheal OVA-induced contraction was observed only in R group. AI-AHR magnitude showed a direct association with OVA-IgG1 and OVA-IgA levels. The extent of AI-AO correlated directly with OVA-IgE and inversely with OVA-IgA levels.. Our data suggest that TxA2 and histamine participate in AI-AO likely through an IgE mechanism. AI-AHR might occur independently of AI-AO, contractile mediators release, and airway inflammatory cell infiltration, but IgA and IgG1 seem to be involved.

Topics: Airway Obstruction; Animals; Antigens; Asthma; Bronchoalveolar Lavage Fluid; Disease Models, Animal; Guinea Pigs; Histamine; Humans; Immunization; Immunoglobulins; Leukotriene D4; Male; Ovalbumin; Respiratory Hypersensitivity; Thromboxane A2

Chronic Chagas' disease affects 10-30 % of patients infected with Trypanosoma cruzi, and it mainly manifests as cardiomyopathy. Important pathophysiological mechanisms involved in the cardiac lesions include activation of the endothelium and induced microvascular alterations. These processes involve the production of endothelial adhesion molecules and thromboxane A2, which are involved in inflammatory cell recruitment and platelet aggregation, respectively. Cyclooxygenase inhibitors such as aspirin decrease thromboxane production and alter the course of Chagas' disease, both in the acute and chronic phases. We studied the effects of the administration of low and high doses of aspirin during the early phase of T. cruzi infection, following microvascular damage in the context of a chronic murine model of Chagas' disease. The effects of both schedules were assessed at 24 and 90 days postinfection by evaluating parasitemia, mortality, and cardiac histopathological changes as well as the expression of ICAM, VCAM, and E-selectin in cardiac tissue. Thromboxane A2, soluble ICAM, and E-selectin blood levels were also measured. While aspirin did not affect parasitemia or mortality in the infected mice, it decreased both cardiac inflammatory infiltrates and thromboxane levels. Additionally, at 90 days postinfection, aspirin normalized sICAM and sE-selectin levels. Considering the improved endothelial function induced by aspirin, we propose the possibility of including this drug in clinical therapy to treat chronic Chagas' disease.

Topics: Animals; Anti-Inflammatory Agents; Aspirin; Chagas Cardiomyopathy; Chronic Disease; Disease Models, Animal; Endothelium, Vascular; Enzyme Inhibitors; Male; Mice; Mice, Inbred BALB C; Parasitemia; Survival Analysis; Thromboxane A2

A contributing factor to increased peripheral resistance seen during hypertension is an increased production of endothelium-derived contractile factors (EDCFs). The main EDCFs are vasoconstrictor prostanoids, metabolites of arachidonic acid (AA) produced by Ca(2+)-dependent cytosolic phospholipase A2 (cPLA2) following phosphorylation (at Ser(505)) mediated by extracellular signal-regulated kinase (ERK1/2) and cyclooxygenase (COX) activations. Although endoplasmic reticulum (ER) stress has been shown to contribute to pathophysiological alterations in cardiovascular diseases, the relationship between ER stress and EDCF-mediated responses remains unclear. We tested the hypothesis that ER stress plays a role in EDCF-mediated responses via activation of the cPLA2/COX pathway in the aorta of the spontaneously hypertensive rat (SHR). Male SHR and Wistar-Kyoto rats (WKY) were treated with ER stress inhibitor, tauroursodeoxycholic acid or 4-phenlybutyric acid (TUDCA or PBA, respectively, 100 mg·kg(-1)·day(-1) ip) or PBS (control, 300 μl/day ip) for 1 wk. There was a decrease in systolic blood pressure in SHR treated with TUDCA or PBA compared with control SHR (176 ± 3 or 181 ± 5, respectively vs. 200 ± 2 mmHg). In the SHR, treatment with TUDCA or PBA normalized aortic (vs. control SHR) 1) contractions to acetylcholine (ACh), AA, and tert-butyl hydroperoxide, 2) ACh-stimulated releases of prostanoids (thromboxane A2, PGF2α, and prostacyclin), 3) expression of COX-1, 4) phosphorylation of cPLA2 and ERK1/2, and 5) production of H2O2. Our findings demonstrate a novel interplay between ER stress and EDCF-mediated responses in the aorta of the SHR. Moreover, ER stress inhibition normalizes such responses by suppressing the cPLA2/COX pathway.

Topics: Acetylcholine; Animals; Antihypertensive Agents; Aorta; Arachidonic Acid; bcl-2-Associated X Protein; Blood Pressure; Cells, Cultured; Cyclooxygenase 1; Dinoprost; Disease Models, Animal; Dose-Response Relationship, Drug; Endoplasmic Reticulum Stress; Endothelium, Vascular; Epoprostenol; Hydrogen Peroxide; Hypertension; Male; Membrane Proteins; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Phenylbutyrates; Phospholipases A2, Cytosolic; Phosphorylation; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Signal Transduction; Taurochenodeoxycholic Acid; tert-Butylhydroperoxide; Thromboxane A2; Vasoconstriction; Vasoconstrictor Agents; Vasodilator Agents

Resveratrol, a polyphenol found in a variety of fruits, exerts a wide range of beneficial effects on the endothelium, regulates multiple vasoactive substances and decreases oxidative stress, factors involved in the pathophysiology of portal hypertension. Our study aimed at evaluating the effects of resveratrol on hepatic and systemic hemodynamics, hepatic endothelial dysfunction, and hepatic fibrosis in CCl₄ cirrhotic rats.. Resveratrol (10 and 20 mg/kg/day) or its vehicle was administered to cirrhotic rats for two weeks and hepatic and systemic hemodynamics were measured. Moreover, we evaluated endothelial function by dose-relaxation curves to acetylcholine, hepatic NO bioavailability and TXA2 production. We also evaluated liver fibrosis by Sirius Red staining of liver sections, collagen-1, NFκB, TGFβ mRNA expression, and desmin and α-smooth muscle actin (α-SMA) protein expression, as a surrogate of hepatic stellate cell activation.. Resveratrol administration significantly decreased portal pressure compared to vehicle (12.1 ± 0.9 vs. 14.3 ± 2.2 mmHg; p <0.05) without significant changes in systemic hemodynamics. Reduction in portal pressure was associated with an improved vasodilatory response to acetylcholine, with decreased TXA2 production, increased endothelial NO, and with a significant reduction in liver fibrosis. The decrease in hepatic fibrosis was associated with a reduced collagen-1, TGFβ, NFκB mRNA expression and desmin and α-SMA protein expression.. Resveratrol administration reduces portal pressure, hepatic stellate cell activation and liver fibrosis, and improves hepatic endothelial dysfunction in cirrhotic rats, suggesting it may be a useful dietary supplement in the treatment of portal hypertension in patients with cirrhosis.

Topics: Animals; Antioxidants; Carbon Tetrachloride; Disease Models, Animal; Dose-Response Relationship, Drug; Endothelium, Vascular; Hypertension, Portal; Liver; Liver Cirrhosis; Liver Cirrhosis, Experimental; Male; Nitric Oxide Synthase Type III; Portal Pressure; Rats; Rats, Wistar; Resveratrol; Stilbenes; Thromboxane A2

Tumor-associated inflammation is a driving force in several adult cancers and intake of low-dose aspirin has proven to reduce cancer incidence. Little is known about tumor-associated inflammation in pediatric neoplasms and no in vivo data exists on the effectiveness of low-dose aspirin on established tumors. The present study employs the transgenic TH-MYCN mouse model for neuroblastoma (NB) to evaluate inflammatory patterns paralleling tumor growth in vivo and low-dose aspirin as a therapeutic option for high-risk NB. Spontaneously arising abdominal tumors were monitored for tumor-associated inflammation ex vivo at various stages of disease and homozygous mice received daily low-dose aspirin (10mg/kg) using oral gavage or no treatment, from 4.5 to 6 weeks of age. Using flow cytometry, a transition from an adaptive immune response predominated by CD8(+) T cell in early neoplastic lesions, towards enrichment in immature cells of the innate immune system, including myeloid-derived suppressor cells, dendritic cells and tumor-associated macrophages, was detected during tumor progression. An M1 to M2 transition of tumor-associated macrophages was demonstrated, paralleled by a deterioration of dendritic cell status. Treatment with low-dose aspirin to mice homozygous for the TH-MYCN transgene significantly reduced the tumor burden (P < 0.01), the presence of tumor-associated cells of the innate immune system (P < 0.01), as well as the intratumoral expression of transforming growth factor-β, thromboxane A2 (P < 0.05) and prostaglandin D2 (P < 0.01). In conclusion, tumor-associated inflammation appears as a potential therapeutic target in NB and low-dose aspirin reduces tumor burden in the TH-MYCN transgenic mouse model of NB, hence warranting further studies on aspirin in high-risk NB.

Topics: Animals; Aspirin; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Cytokines; Dendritic Cells; Disease Models, Animal; Disease Progression; Homozygote; Immunity, Innate; Inflammation; Macrophages; Mice; Mice, Transgenic; Neuroblastoma; Prostaglandin D2; Th2 Cells; Thromboxane A2; Transforming Growth Factor beta

Metformin is an insulin sensitizing agent with beneficial effects in diabetic patients on glycemic levels and in the cardiovascular system. We examined whether the metabolic changes and the vascular dysfunction in monosodium glutamate-induced obese non-diabetic (MSG) rats might be improved by metformin.. 16 week-old MSG rats were treated with metformin for 15 days and compared with age-matched untreated MSG and non-obese non-diabetic rats (control). Blood pressure, insulin sensitivity, vascular reactivity and prostanoid release in the perfused mesenteric arteriolar bed as well as nitric oxide production and reactive oxygen species generation in isolated mesenteric arteries were analyzed.. 18-week-old MSG rats displayed higher Lee index, fat accumulation, dyslipidemia, insulin resistance and hyperinsulinemia. Metformin treatment improved these alterations. The norepinephrine-induced response, increased in the mesenteric arteriolar bed from MSG rats, was corrected by metformin. Indomethacin corrected the enhanced contractile response in MSG rats but did not affect metformin effects. The sensitivity to acetylcholine, reduced in MSG rats, was also corrected by metformin. Indomethacin corrected the reduced sensitivity to acetylcholine in MSG rats but did not affect metformin effects. The sensitivity to sodium nitroprusside was increased in preparations from metformin-treated rats. Metformin treatment restored both the reduced PGI2/TXA2 ratio and the increased reactive oxygen species generation in preparations from MSG rats.. Metformin improved the vascular function in MSG rats through reduction in reactive oxygen species generation, modulation of membrane hyperpolarization, correction of the unbalanced prostanoids release and increase in the sensitivity of the smooth muscle to nitric oxide.

Topics: Acetylcholine; Animals; Blood Pressure; Body Weight; Disease Models, Animal; Dyslipidemias; Epoprostenol; Hyperinsulinism; Hypoglycemic Agents; Indomethacin; Insulin; Insulin Resistance; Male; Mesenteric Arteries; Metformin; Nitric Oxide; Nitric Oxide Synthase; Nitroprusside; Norepinephrine; Obesity; Rats; Rats, Wistar; Reactive Oxygen Species; Sodium Glutamate; Thromboxane A2

Mast cells are important cells of the immune system and are recognized as participants in the pathogenesis of atherosclerosis. In this study, we evaluated the role of mast cells on the progression of atherosclerosis and hepatic steatosis using the apolipoprotein E-deficient (ApoE(-/-)) and ApoE(-/-)/mast cell-deficient (Kit(W-sh/W-sh)) mouse models maintained on a high-fat diet. The en face analyses of aortas showed a marked reduction in plaque coverage in ApoE(-/-)/Kit(W-sh/W-sh) compared with ApoE(-/-) after a 6-mo regimen with no significant change noted after 3 mo. Quantification of intima/media thickness on hematoxylin and eosin-stained histological cross sections of the aortic arch revealed no significant difference between ApoE(-/-) and ApoE(-/-)/Kit(W-sh/W-sh) mice. The high-fat regimen did not induce atherosclerosis in either Kit(W-sh/W-sh) or wild-type mice. Mast cells with indications of degranulation were seen only in the aortic walls and heart of ApoE(-/-) mice. Compared with ApoE(-/-) mice, the serum levels of total cholesterol, low-density lipoprotein and high-density lipoprotein were decreased by 50% in ApoE(-/-)/Kit(W-sh/W-sh) mice, whereas no appreciable differences were noted in serum levels of triglycerides or very low density lipoprotein. ApoE(-/-)/Kit(W-sh/W-sh) mice developed significantly less hepatic steatosis than ApoE(-/-) mice after the 3-mo regimen. The analysis of Th1/Th2/Th17 cytokine profile in the sera revealed significant reduction of interleukin (IL)-6 and IL-10 in ApoE(-/-)/Kit(W-sh/W-sh) mice compared with ApoE(-/-) mice. The assessment of systemic generation of thromboxane A(2) (TXA(2)) and prostaglandin I(2) (PGI(2)) revealed significant decrease in the production of PGI(2) in ApoE(-/-)/Kit(W-sh/W-sh) mice with no change in TXA(2). The decrease in PGI(2) production was found to be associated with reduced levels of cyclooxygenase-2 mRNA in the aortic tissues. A significant reduction in T-lymphocytes and macrophages was noted in the atheromas of the ApoE(-/-)/Kit(W-sh/W-sh) mice. These results demonstrate the direct involvement of mast cells in the progression of atherosclerosis and hepatic steatosis.

Topics: Animals; Aorta; Apolipoproteins E; Atherosclerosis; Carotid Intima-Media Thickness; Cytokines; Diet, High-Fat; Disease Models, Animal; Disease Progression; Epoprostenol; Fatty Liver; Macrophages; Male; Mast Cells; Mice; Mice, Knockout; Plaque, Atherosclerotic; T-Lymphocytes; Thromboxane A2

Fetal growth restriction (FGR) remains a cause of perinatal brain injury, sometimes leading to neurological and intellectual impairment. Although the mechanisms and pathophysiology of CNS injuries have not been elucidated completely, it is possible carbohydrate and energy metabolism may have an important role in the FGR brain. In this study, FGR was induced in rats by administration of synthetic thromboxane A2 (STA2). Pups were delivered by cesarean section. After killing, samples were obtained from the fetuses of both control and FGR rats for evaluation of carbohydrate and energy metabolism in brain tissue. Lactate and pyruvate levels in brain were reduced significantly in the FGR group. Glucose content in brain tissue tended to be increased in the FGR group. In contrast, glycogen content in brain tissue tended to be lower in the FGR group. However, these differences in glucose and glycogen content did not reach statistical significance. Brain high-energy reserves, including ATP, ADP, AMP, and phosphocreatine (P-Cr), were similar in the control and FGR groups. Gluconeogenesis compensated for chronic fetal hypoxia and decreased glycogen storage. Energy metabolism in the FGR brain is likely to be disrupted as a consequence of lower reserves of energy substrates.

Topics: Animals; Brain; Carbohydrate Metabolism; Cesarean Section; Disease Models, Animal; Energy Metabolism; Female; Fetal Growth Retardation; Fetal Hypoxia; Fetal Weight; Gestational Age; Gluconeogenesis; Organ Size; Placental Circulation; Pregnancy; Rats; Rats, Sprague-Dawley; Thromboxane A2

Glitazones exhibit beneficial effects in the vascular system, both on large vessels and at a microcirculatory level. We previously reported the effects of glitazones in the aorta of spontaneously hypertensive rats (SHR). We focus now on the acute and long-term actions of these drugs on mesenteric resistance arteries of the SHR. Incubation with pioglitazone or rosiglitazone (10⁻⁵ mol/l) improved endothelium-dependent relaxations to acetylcholine and the endothelial modulation of phenylephrine contractions. Acetylcholine relaxations that were abolished by N(G)-nitro-L-arginine methylester were partly recovered by the glitazones, but no effects of these drugs were observed in the presence of indomethacin or indomethacin + L-NAME. Glitazones did not change the contractions to U46619 or the endothelium-independent relaxation to sodium nitroprusside. Three-week oral pioglitazone or rosiglitazone treatment (3 and 10 mg/kg/day, respectively) confirmed the acute experiments. Thus, in microvessels, glitazones improve endothelial function in such a way that they do not alter endothelial nitric oxide release but reduce the production of vasoconstrictor prostanoids from endothelial cells.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Acetylcholine; Animals; Blood Pressure; Bridged Bicyclo Compounds, Heterocyclic; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Endothelium, Vascular; Epinephrine; Fatty Acids, Unsaturated; Hydrazines; Hypertension; Hypoglycemic Agents; Indomethacin; Male; Mesenteric Arteries; Muscle, Smooth, Vascular; NG-Nitroarginine Methyl Ester; Nitroprusside; Pioglitazone; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Rosiglitazone; Thiazolidinediones; Thromboxane A2; Vascular Resistance; Vasoconstrictor Agents; Vasodilator Agents

Background and Purpose- Hyperlipidemia is associated with platelet hyperreactivity. We hypothesized that L-4F, an apolipoprotein A-I mimetic peptide, would inhibit platelet aggregation in hyperlipidemic mice.. Injecting L-4F into apolipoprotein E (apoE)-null and low-density lipoprotein receptor-null mice resulted in a significant reduction in platelet aggregation in response to agonists; however, there was no reduction in platelet aggregation after injection of L-4F into wild-type (WT) mice. Consistent with these results, injection of L-4F into apoE-null mice prolonged bleeding time; the same result was not found in WT mice. Incubating L-4F in vitro with apoE-null platelet-rich plasma also resulted in decreased platelet aggregation. However, incubating washed platelets from either apoE-null or WT mice with L-4F did not alter aggregation. Compared with WT mice, unstimulated platelets from apoE-null mice contained significantly more 12-hydroxy 5,8,10,14-eicosatetraenoic acid, thromboxane A(2), and prostaglandins D(2) and E(2). In response to agonists, platelets from L-4F-treated apoE-null mice formed significantly less thromboxane A(2), prostaglandins D(2) and E(2), and 12-hydroxy 5,8,10,14-eicosatetraenoic acid.. By binding plasma-oxidized lipids that cause platelet hyperreactivity in hyperlipidemic mice, L-4F decreases platelet aggregation.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adenosine Diphosphate; Animals; Apolipoprotein A-I; Apolipoproteins E; Arachidonic Acid; Blood Coagulation; Collagen; Dinoprostone; Disease Models, Animal; Hyperlipidemias; Injections, Subcutaneous; Mice; Mice, Inbred C57BL; Mice, Knockout; Molecular Mimicry; Peptides; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Function Tests; Prostaglandin D2; Receptors, LDL; Thromboxane A2

Angiotensin II has a key role in the control of resistance artery tone and local blood flow. Angiotensin II possesses 2 main receptors. Although angiotensin II type 1 receptor is well known and is involved in the vasoconstrictor and growth properties of angiotensin II, the role of the angiotensin II type 2 receptor (AT2R) remains much less understood. Although AT2R stimulation induces vasodilatation in normotensive rats, it induces vasoconstriction in pathological conditions involving oxidative stress and cyclooxygenase 2 expression. Thus, we studied the influence of cyclooxygenase 2 on AT2R-dependent tone in diabetes mellitus. Mesenteric resistance arteries were isolated from Zucker diabetic fatty (ZDF) and lean Zucker rats and studied using in vitro using wire myography. In ZDF rats, AT2R-induced dilation was lower than in lean rats (11% versus 21% dilation). Dilation in ZDF rats returned to the control (lean rats) level after acute superoxide reduction (Tempol and apocynin), cyclooxygenase 2 inhibition (NS398), or thromboxane A(2) synthesis inhibition (furegrelate). Cyclooxygenase 2 expression and superoxide production were significantly increased in ZDF rat arteries compared with arteries of lean rats. After chronic treatment with Tempol, AT2R-dependent dilation was equivalent in ZDF and lean rats. Chronic treatment of ZDF rats with NS398 also restored AT2R-dependent dilation to the control (lean rats) level. Plasma thromboxane B(2) (thromboxane A(2) metabolite), initially high in ZDF rats, was decreased by chronic Tempol and by chronic NS398 to the level found in lean Zucker rats. Thus, in type 2 diabetic rats, superoxide and thromboxane A(2) reduced AT2R-induced dilation. These findings are important to take into consideration when choosing vasoactive drugs for diabetic patients.

Topics: Analysis of Variance; Animals; Blotting, Western; Cyclic N-Oxides; Cyclooxygenase 2; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Disease Models, Animal; Male; Mesenteric Arteries; Microscopy, Confocal; Probability; Random Allocation; Rats; Rats, Zucker; Reactive Oxygen Species; Receptor, Angiotensin, Type 2; Spin Labels; Thromboxane A2; Vascular Resistance; Vasodilation

We investigated the effects of vaporized perfluorohexane (PFH) on pulmonary vascular tone, pulmonary vascular resistance and peak inspiratory pressure as well as lipid mediator formation in the treatment of calcium ionophore induced lung injury in a model of the isolated perfused and ventilated rabbit lungs.. Lung injury was induced in isolated perfused and ventilated rabbit lungs by calcium ionophore A23187. Lungs were treated with either 4.5 vol.% (4.5 vol.% PFH; n = 6) or 18 vol.% (18 vol.% PFH; n = 6) PFH. Six lungs remained untreated (Control). In addition 5 lungs (PFH-sham) remained uninjured receiving 18 vol.% PFH only. Mean pulmonary artery pressure (mPAP), peak inspiratory pressure (P(max)), and lung weight (weight) were monitored for 120 min. Experiments were terminated before when the increase in lung weight exceeded 40 g. Perfusate samples were taken at regular intervals for analysis of TXB(2), 6-keto-PGF(1) and LTB(4).. Controls reached the study end point significantly earlier than both PFH groups. Significant differences were found for a weight gain of 10 g and 20 g between the control and the 4.5 vol.% PFH and the 18 vol.% PFH. Differences in mPAP were more pronounced in the 4.5 vol.% PFH. However increases in P(max) were more marked in 4.5 vol.% PFH. TXA(2)-, PGI(2)-, and LTB(4)-levels were significantly lower in PFH groups. Uninjured lungs remained unaffected by the presence of 18 vol.% PFH.. Inflammatory lung injury was attenuated by the treatment with 4.5 vol.% PFH and 18 vol.% PFH vapor in the isolated perfused rabbit lung. Therapeutic effects were more pronounced with a concentration of 4.5 vol.% PFH.

Topics: Animals; Calcimycin; Disease Models, Animal; Dose-Response Relationship, Drug; Epoprostenol; Female; Fluorocarbons; In Vitro Techniques; Ionophores; Leukotriene B4; Lung; Lung Injury; Organ Size; Positive-Pressure Respiration; Pulmonary Artery; Pulmonary Circulation; Pulmonary Edema; Rabbits; Thromboxane A2; Vascular Resistance; Volatilization

The production of thromboxane A(2) (TXA(2)) and prostacyclin (prostaglandin I(2), PGI(2)) is known to be increased in patients with atherosclerosis. In this study, we evaluated the influence of gender on TXA(2) and PGI(2) production, and their association with the progression of atherosclerosis in apolipoprotein E-null (ApoE(-/-)) mice maintained on a high fat diet for 3 months. En face analyses of aortas showed marked increases in plaque formation in female ApoE(-/-) mice. Quantification of the hematoxylin/eosin (H&E) stained cross sections of the aortic arch revealed 3 to 4-fold higher plaque thickness in female ApoE(-/-) mice. Analyses of 24-hours urine samples for 11-dehydro TXB(2) and 2, 3-dinor-6-keto PGF(1a) indicated that female ApoE(-/-) mice produce up to 15-fold more TXA(2) and 50% less PGI(2) than the age matched males. Interestingly, the serum cholesterol levels in ApoE(-/-) females were 20% lower than males on the high fat regimen. No gender-associated changes in the number of T lymphocytes, mast cells and macrophages were evident in the lesion areas of ApoE(-/-) mice. The results suggest that the markedly elevated TXA(2) production and reduced PGI(2) production are gender-related proatherogenic risk factors in female ApoE(-/-) mice.

Topics: Animals; Aorta; Apolipoproteins E; Atherosclerosis; Blood Chemical Analysis; Disease Models, Animal; Epoprostenol; Estradiol; Female; Lipids; Macrophages; Male; Mast Cells; Mice; Mice, Knockout; Sex Characteristics; T-Lymphocytes; Thromboxane A2

Fetal growth retardation (FGR) is a critical problem in the neonatal period, because a substantial population of infants born with FGR go on to develop various developmental disorders. In the present study, we produced FGR model rats by continuous administration of a synthetic thromboxane A2 analogue (STA2) to pregnant rats. The FGR pups exhibited a significant delay in postnatal neurological development. Moreover, behavioral analyses revealed the presence of a learning disability in juvenile FGR male rats. To investigate the mechanism underlying the neurological disorders, histological and biochemical analyses of the brain of FGR rats were performed. The density of neurons in the cortical plate of an FGR brain was low compared with the brains of a similarly aged, healthy rat. Consistent with this finding, the density of TUNEL-positive cells was higher in the cortical plate of FGR brains. Western blot analyses showed that the levels of three brain-specific chondroitin sulfate proteoglycans (CSPGs), neurocan, phosphacan, and neuroglycan C, were all significantly reduced in the brain of neonatal FGR rats compared with those of the control. The reduction of CSPG-levels and morphological changes in the brain may be relevant to neurological dysfunction in FGR.

Topics: Animals; Animals, Newborn; Brain; Cell Count; Cerebral Cortex; Chondroitin Sulfate Proteoglycans; Developmental Disabilities; Disease Models, Animal; Female; Fetal Growth Retardation; Growth Inhibitors; Humans; Infant, Newborn; Learning Disabilities; Male; Membrane Proteins; Neurocan; Pregnancy; Proteoglycans; Rats; Rats, Sprague-Dawley; Receptor-Like Protein Tyrosine Phosphatases, Class 5; Thromboxane A2

The effect of a herbal medicine, Sho-seiryu-to (TJ-19), on oleic acid-induced lung injury, an animal model of acute respiratory distress syndrome or acute lung injury (ARDS/ALI), was examined.. Acute lung injury was induced by an intravenous injection of 15 microl/kg oleic acid to guinea-pigs. TJ-19 was administered by a single oral dose (3 g/kg) or by multiple oral doses (0.75 g/kg).. The decrease in partial oxygen pressure of arterial blood (Pao(2)) and the increase in airway vascular permeability induced by the oleic acid injection were attenuated by a single dose of TJ-19. When TJ-19 was administered orally twice a day for two weeks and then oleic acid was injected, a potent prophylactic effect of the drug was observed. TJ-19 also prevented airway vascular hyperpermeability, lung cell injury, oxidative stress and thromboxane A(2) generation, associated with the oleic acid injection.. TJ-19 significantly attenuated the oleic acid-induced lung injury probably through the antioxidative effect and inhibitory effect of thromboxane A(2) generation, although the precise inhibitory mechanisms were not fully elucidated due to the diversity in constituents of the herbal medicine. We suggest that TJ-19 is a promising drug candidate and a medicinal resource for preventing ARDS/ALI.

Topics: Acute Lung Injury; Animals; Capillary Permeability; Disease Models, Animal; Drugs, Chinese Herbal; Guinea Pigs; Herbal Medicine; Male; Oleic Acid; Oxidative Stress; Phytotherapy; Plants, Medicinal; Thromboxane A2

To observe the changes in systemic hemodynamics and their relations to the concentrations of nitric oxide, endothelin, prostacyclin, and thromboxane A2 after portal cavity clamping and opening in portal hypertensive canines.. Twelve canines were randomly divided into control group and model group, and partial ligation of the portal vein was performed in the model group. Portal cavity clamping and opening was performed 12 weeks later in the two groups. The hemodynamic parameters including cardiac output index (CI), heart rate (HR), mean artery blood pressure (MABP), central venous pressure (CVP), pulmonary arteriole wedge pressure (PAWP), and systemic vascular resistance index (SVRI) were measured during the operation. Samples were obtained from the central vein at 3 time points during the operation for measuring NO, ET, PGI2, and TXA2.. Portal vein ligation and portal cavity clamping produced obvious changes in the systemic circulation of the dogs, and the alteration was milder in the control group. After obstruction of the portal vein, the NO levels in systemic circulation in portal hypertensive dogs declined obviously, but gradually recovered the normal level after reperfusion.. Systemic circulation undergoes significant alterations after portal vein obstruction, but its changes in portal hypertensive dogs are milder than those in the control group, the mechanism of which needs further investigation.

Topics: Animals; Disease Models, Animal; Dogs; Endothelins; Epoprostenol; Hemodynamics; Hypertension, Portal; Nitric Oxide; Plasma; Portal Vein; Thromboxane A2; Vena Cava, Inferior

To explore the influence of intensive insulin therapy on the intestinal microcirculatory dysfunction of rats suffering from sepsis.. The sepsis model of rat was reproduced by cecal ligation and puncture. Forty-eight male Sprague-Dawley (SD) rats were randomly divided into control group, sepsis group, and insulin treatment group (n =16 in each group). The intestinal tissue was harvested in the experimental groups before and 3, 6, 12 and 24 hours after insulin administration. Platelet activating factor (PAF), prostacyclin (PGI(2)) and thromboxane (TXA(2)) in the intestine were measured by radioimmunoassay.. The levels of PAF, PGI and TXA(2) were significantly elevated in sepsis group at 3 hours, and peaked at 6 hours, then decreased gradually. At each time point they were higher in sepsis group compared with that of control group (all P<0.05), especially TXA(2), which was more evident, while PGI(2)/TXA(2) ratio showed a lowering. In contrast, PAF, PGI(2) and TXA(2) were significantly decreased in insulin treatment group compared with the sepsis group, especially TXA(2), which was more evident ( all P<0.05), but PGI(2)/TXA(2) ratio showed an elevation.. Insulin plays an important role in amelioration of microcirculatory dysfunction in sepsis. Through improving the disorder of PGI(2)/TXA(2)system and antagonising the expression of PAF, insulin alleviates vasospasm, inhibits platelet aggregation and thrombosis, thus protecting the function of intestine.

Topics: Animals; Disease Models, Animal; Epoprostenol; Insulin; Intestinal Mucosa; Intestines; Male; Microcirculation; Platelet Activating Factor; Random Allocation; Rats; Rats, Sprague-Dawley; Sepsis; Thromboxane A2

This study determined if altered vascular prostacyclin (PGI(2)) and/or thromboxane A(2) (TxA(2)) production with reduced Po(2) contributes to impaired hypoxic dilation of skeletal muscle resistance arterioles of obese Zucker rats (OZRs) versus lean Zucker rats (LZRs). Mechanical responses were assessed in isolated gracilis muscle arterioles following reductions in Po(2) under control conditions and following pharmacological interventions inhibiting arachidonic acid metabolism and nitric oxide synthase and alleviating elevated vascular oxidant stress. The production of arachidonic acid metabolites was assessed using pooled arteries from OZRs and LZRs in response to reduced Po(2). Hypoxic dilation, endothelium-dependent in both strains, was attenuated in OZRs versus LZRs. Nitric oxide synthase inhibition had no significant impact on hypoxic dilation in either strain. Cyclooxygenase inhibition dramatically reduced hypoxic dilation in LZRs and abolished responses in OZRs. Treatment of arterioles from OZRs with polyethylene glycol-superoxide dismutase improved hypoxic dilation, and this improvement was entirely cyclooxygenase dependent. Vascular PGI(2) production with reduced Po(2) was similar between strains, although TxA(2) production was increased in OZRs, a difference that was attenuated by treatment of vessels from OZRs with polyethylene glycol-superoxide dismutase. Both blockade of PGH(2)/TxA(2) receptors and inhibition of thromboxane synthase increased hypoxic dilation in OZR arterioles. These results suggest that a contributing mechanism underlying impaired hypoxic dilation of skeletal muscle arterioles of OZRs may be an increased vascular production of TxA(2), which competes against the vasodilator influences of PGI(2). These results also suggest that the elevated vascular oxidant stress inherent in metabolic syndrome may contribute to the increased vascular TxA(2) production and may blunt vascular sensitivity to PGI(2).

Topics: Animals; Arterioles; Bridged Bicyclo Compounds, Heterocyclic; Cyclooxygenase Inhibitors; Disease Models, Animal; Enzyme Inhibitors; Epoprostenol; Fatty Acids, Unsaturated; Free Radical Scavengers; Hydrazines; Hypoxia; Imidazoles; Indomethacin; Male; Muscle, Skeletal; NG-Nitroarginine Methyl Ester; Nitric Oxide Synthase; Obesity; Oxidative Stress; Polyethylene Glycols; Rats; Rats, Zucker; Receptors, Thromboxane; Superoxide Dismutase; Thromboxane A2; Thromboxane-A Synthase; Up-Regulation; Vasodilation

Sepsis is an archetypal condition with molecular links between inflammation and coagulation. Both events can be orchestrated by the interaction between circulating and vascular cells that under activation release microparticles.. We characterized circulating microparticles from both nonseptic subjects and patients with septic shock and evaluated their contribution to vascular function.. Circulating microparticles and their cell origin were measured in blood from 36 patients with septic shock and 18 nonseptic subjects by flow cytometry. Microparticles were then injected intravenously into mice and vascular reactivity was assessed in aorta. Expression and activity of enzymes involved in nitric oxide (NO) and cyclooxygenase metabolite production were analyzed.. Circulating levels of microparticles and platelet- and endothelial-derived microparticles were increased in septic patients. Surprisingly, septic microparticles enhanced the sensitivity of contraction of mouse aorta in response to serotonin. Interestingly, septic microparticles enhanced the contraction of aorta from lipopolysaccharide-treated mice. This effect was linked neither to increased calcium entry nor to Rho kinase inhibitor-sensitive mechanisms. In addition, the effect of septic microparticles was not modified either by NO-synthase or cyclooxygenase-2 inhibitors, and was not associated with NO or O2- overproduction. The nonselective cyclooxygenase-2 inhibitor indomethacin reduced, and the specific thromboxane A2 antagonist SQ-29548 abolished, aortic contraction in mice treated with nonseptic and septic microparticles. The effect of septic microparticles was associated with increased thromboxane A2 production, and was sensitive to a selective thromboxane A2 antagonist.. We provide evidence that increased circulating microparticles are protective against vascular hyporeactivity accounting for hypotension in patients with septic shock.

Topics: Adult; Aged; Animals; Case-Control Studies; Cell-Derived Microparticles; Disease Models, Animal; Endothelium, Vascular; Female; Humans; Hypotension; Male; Mice; Middle Aged; Shock, Septic; Thromboxane A2; Vasoconstriction; Vasodilation

Clinical and experimental evidence has shown that myocardial ischemia activates cardiac spinal afferents that mediate sympathoexcitatory reflex responses. During myocardial ischemia, thromboxane A2 (TxA2) is released in large quantities by activated platelets in the coronary circulation of patients with coronary artery disease. We hypothesized that endogenous TxA2 contributes to sympathoexcitatory reflexes during myocardial ischemia through stimulation of TxA2/prostaglandin endoperoxide (TP) receptors. Regional myocardial ischemia was induced by occlusion of a diagonal branch of left anterior descending coronary artery of anesthetized cats. Hemodynamic parameters and renal sympathetic nerve activity were recorded after sinoaortic denervation and bilateral vagotomy. Regional myocardial ischemia evoked significant increases in mean blood pressure (122+/-10 vs. 139+/-12 mmHg, before vs. ischemia), aortic flow (153+/-18 vs. 167+/-20 ml/min), first derivative of left ventricular pressure at 40-mmHg developed pressure (2,736+/-252 vs. 2,926+/-281 mmHg/s), systemic vascular resistance (0.6+/-0.1 vs. 0.9+/-0.12 peripheral resistance units), and renal sympathetic nerve activity (by 22%). The reflex nature of the excitatory responses was confirmed by observing its disappearance after blockade of cardiac nerve transmission with intrapericardial 2% procaine treatment. Moreover, application of U-46619 (2.5-10 microg), a TxA2 mimetic, on the heart caused graded increases in mean arterial pressure and renal nerve activity, responses that were abolished 3 min after local blockade of cardiac neural transmission with intrapericardial procaine. BM 13,177 (30 mg/kg iv), a selective TP receptor antagonist, eliminated the reflex responses to U-46619 and significantly attenuated the excitatory responses during brief (5 min) regional myocardial ischemia. The sympathoexcitatory reflex responses to U-46619 were unchanged by blockade of histamine H1 receptors with pyrilamine and serotonin 5-HT3 receptors with tropisetron, indicating specificity of this TP receptor agonist. These data indicate that endogenous TxA2 participates in myocardial ischemia-mediated sympathoexcitatory reflex responses through a TP receptor mechanism.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Anesthetics, Local; Animals; Cats; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Heart; Hemodynamics; Histamine H1 Antagonists; Indoles; Kidney; Male; Myocardial Ischemia; Pressoreceptors; Procaine; Pyrilamine; Receptors, Thromboxane; Reflex; Serotonin Antagonists; Sulfonamides; Sympathetic Nervous System; Thromboxane A2; Tropisetron; Vagotomy

Hypoxia-induced neonatal persistent pulmonary hypertension (PPHN) is characterized by sustained vasospasm and increased thromboxane (TxA2)-to-prostacyclin ratio. We previously demonstrated that moderate hypoxia induces myocyte TxA2 hypersensitivity. Here, we examined TxA2 prostanoid receptor (TP-R) localization and kinetics following hypoxia to determine the mechanism of hypoxia-induced TxA2 hypersensitivity. Primary cultured neonatal pulmonary artery myocytes were exposed to 10% O2 (hypoxic myocytes; HM) or 21% O2 (normoxic myocytes; NM) for 3 days. PPHN was induced in neonatal piglets by in vivo exposure to 10% FiO2 for 3 days. TP-R was studied in whole lung sections from pigs with hypoxic PPHN- and age-matched controls; intracellular localization was studied by immunocytochemistry. TP-R affinity was studied in cultured myocytes by saturation binding kinetics using 3H-SQ-29548 and competitive binding kinetics by coincubation with U-46619. Phosphorylation and coupling were examined in immunoprecipitated TP-R. We report distal propagation of TP-R expression in PPHN, extending to pulmonary arteries <50 microm. In HM, intracellular TP-R moves towards the perinuclear region, mirroring a change in endoplasmic reticulum (ER) morphology. TP-R kinetics also alter in HM membranes, with decreased Kd and Bmax (maximal binding sites). Additionally, in hypoxia, 3H-SQ-29548 is displaced at lower concentration of U-46619 than in normoxia, suggesting increased agonist affinity. Phosphorylation of serine residues on HM TP-R was significantly decreased compared with NM; this difference correlated with increased Galphaq coupling in hypoxia and was ablated by incubation with PKA. We conclude that the TP-R is normally desensitized in the neonatal pulmonary circuit by PKA-mediated regulatory phosphorylation, decreasing ligand affinity and coupling to Galphaq; this protection is lost following hypoxic exposure. Also, the appearance of TP-R in resistance arteries after development of hypoxic PPHN may contribute to increased pulmonary arterial pressure.

Topics: Animals; Animals, Newborn; Binding, Competitive; Calcium; Cells, Cultured; Disease Models, Animal; GTP-Binding Protein alpha Subunits, Gq-G11; Hypoxia; Immunoenzyme Techniques; Immunoprecipitation; Kinetics; Ligands; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Phosphorylation; Pulmonary Artery; Receptors, Thromboxane A2, Prostaglandin H2; Swine; Thromboxane A2; Vasoconstriction

We studied whether administration of nitroflurbiprofen (HCT-1026), a cyclooxygenase inhibitor with nitric oxide (NO)-donating properties, modulates the increased intrahepatic vascular tone in portal hypertensive cirrhotic rats.. In vivo hemodynamic measurements (n = 8/condition) and evaluation of the increased intrahepatic resistance by in situ perfusion (n = 5/condition) were performed in rats with thioacetamide-induced cirrhosis that received either nitroflurbiprofen (45 mg/kg), flurbiprofen (30 mg/kg, equimolar concentration to nitroflurbiprofen), or vehicle by intraperitoneal injection 24 hours and 1 hour prior to the measurements. Additionally, we evaluated the effect of acute administration of both drugs (250 micromol/L) on the intrahepatic vascular tone in the in situ perfused cirrhotic rat liver (endothelial dysfunction and hyperresponsiveness to methoxamine) and on hepatic stellate cell contraction in vitro. Typical systemic adverse effects of nonsteroidal anti-inflammatory drugs, such as gastrointestinal ulceration, renal insufficiency, and hepatotoxicity, were actively explored.. In vivo, nitroflurbiprofen and flurbiprofen equally decreased portal pressure (8 +/- 0.8 and 8.4 +/- 0.1 mm Hg, respectively, vs 11.8 +/- 0.6 mm Hg) and reduced the total intrahepatic vascular resistance. Systemic hypotension was not aggravated in the different treatment groups (P = .291). In the perfused cirrhotic liver, both drugs improved endothelial dysfunction and hyperresponsiveness. This was associated with a decreased hepatic thromboxane A(2)-production and an increased intrahepatic nitrate/nitrite level. In vitro, nitroflurbiprofen, more than flurbiprofen, decreased hepatic stellate cells contraction. Flurbiprofen-treated rats showed severe gastrointestinal ulcerations (bleeding in 3/8 rats) and nefrotoxicity, which was not observed in nitroflurbiprofen-treated cirrhotic rats.. Treatment with nitroflurbiprofen, an NO-releasing cyclooxygenase inhibitor, improves portal hypertension without major adverse effects in thioacetamide-induced cirrhotic rats by attenuating intrahepatic vascular resistance, endothelial dysfunction, and hepatic hyperreactivity to vasoconstrictors.

Topics: Animals; Cyclooxygenase Inhibitors; Disease Models, Animal; Dose-Response Relationship, Drug; Endothelium, Vascular; Flurbiprofen; Hypertension, Portal; Kidney Diseases; Liver; Liver Circulation; Liver Cirrhosis, Experimental; Male; Nitric Oxide; Nitric Oxide Donors; Peptic Ulcer; Perfusion; Portal Pressure; Rats; Rats, Wistar; Thioacetamide; Thromboxane A2; Vascular Resistance; Vasoconstriction; Vasodilation

Atherosclerosis is a chronic inflammatory disease of the vasculature influenced by a variety of mediators. Among them, prostanoids, which include prostacyclin and thromboxane (Tx) A(2), have recently received a lot of attention. Previous studies demonstrated that antagonism or deletion of the receptor for TxA(2) retards early atherogenesis in apolipoprotein E-deficient mice, but no data are available in low-density lipoprotein (LDL) receptor deficient mice. In our study, we tested the effect of a novel TxA(2) receptor (TP) antagonist and synthase inhibitor, BM-573, on atherosclerosis development and progression in LDL receptor deficient mice. To this end, the effect of 12 weeks treatment with BM-573 on early or established aortic atherosclerotic lesions of these mice was assessed. In both treatments, while BM-573 did not affect body weight, systolic blood pressure, total plasma cholesterol or triglycerides levels, it partially reduced TxA(2) but did not affect prostacyclin biosynthesis. Moreover, BM-573 significantly decreased early atherogenesis and prevented progression of established atherosclerotic lesions. These results show for the first time that this dual Tx inhibitor is effective in reducing atherogenesis in the LDL receptor deficient mice. They also demonstrate the novel concept that this therapeutic approach halts the progression of the disease and influences the cellular composition of the atherosclerotic plaques.

Topics: Animals; Aorta; Atherosclerosis; Blood Pressure; Body Weight; Cholesterol; Disease Models, Animal; Disease Progression; Epoprostenol; Male; Mice; Mice, Inbred C57BL; Platelet Aggregation Inhibitors; Receptors, LDL; Receptors, Thromboxane; Sulfonylurea Compounds; Thromboxane A2; Triglycerides

Acute respiratory failure is a major complication of severe pneumococcal pneumonia, characterized by impairment of pulmonary microvascular barrier function and pulmonary hypertension. Both features can be evoked by pneumolysin (PLY), an important virulence factor of Streptococcus pneumoniae. We hypothesized that platelet-activating factor (PAF) and associated downstream signaling pathways play a role in the PLY-induced development of acute lung injury.. Controlled, ex vivo laboratory study.. Female Balb/C mice, 8-12 wks old.. Ventilated and blood-free-perfused lungs of wild-type and PAF receptor-deficient mice were challenged with recombinant PLY.. Intravascular PLY, but not the pneumolysoid Pd-B (PLY with a Trp-Phe substitution at position 433), caused an impressive dose-dependent increase in pulmonary vascular resistance and increased PAF in lung homogenates, as detected by reversed-phase high-performance liquid chromatography coupled to tandem mass spectrometry. The pressor response was reduced in lungs of PAF receptor-deficient mice and after PAF receptor blockade by BN 50730. PLY and exogenous PAF increased thromboxane B2 in lung effluate, and thromboxane receptor inhibition by BM 13505 diminished the pressor response to PLY. Differential inhibition of intracellular signaling steps suggested significant contribution of phosphatidylcholine-specific phospholipase C and protein kinase C and of the Rho/Rho-kinase pathway to PLY-induced pulmonary vasoconstriction. Unrelated to the pulmonary arterial pressor response, microvascular leakage of PLY was diminished in lungs of PAF receptor-deficient mice as well.. PAF significantly contributed to PLY-induced acute injury in murine lungs. The PAF-mediated pressor response to PLY depends on thromboxane and on the downstream effectors phosphatidylcholine-specific phospholipase C, protein kinase C, and Rho-kinase.

Topics: Animals; Bacterial Proteins; Disease Models, Animal; Female; Humans; Hypertension, Pulmonary; Intracellular Signaling Peptides and Proteins; Mice; Mice, Inbred BALB C; Platelet Activating Factor; Pneumonia, Pneumococcal; Protein Serine-Threonine Kinases; Respiratory Distress Syndrome; rho-Associated Kinases; Signal Transduction; Streptolysins; Thromboxane A2

Thoracic aortic dissection is a life-threatening complication of Marfan syndrome, a connective tissue disorder caused by mutations in the gene encoding fibrillin-1. We have demonstrated that nitric oxide-mediated endothelial-dependent relaxation is impaired in the thoracic aorta in Marfan syndrome. In the present study, we determined whether the cyclooxygenase (COX)-pathway is involved in the compromised aortic vasomotor function.. Thoracic aortae from mice at 3, 6 and 9 months of age, heterozygous for the Fbn1 allele encoding a cysteine substitution (Fbn1 (C1039G/+), 'Marfan', n=35), were compared with those from age-matched controls (n=35).. Isometric force measurement revealed that preincubation with indomethacin, a non-specific COX inhibitor, but not valeryl salicylate, a specific COX-1 inhibitor, improved the phenylephrine-induced contractions (at 6 months, EC(50) and E(max) were increased 4.5-fold and by 45%, respectively) in Marfan aortae. Sensitivity to acetylcholine-induced relaxation was improved 10-fold. Blockade of the thromboxane-endoperoxide receptor by SQ-29548 did not affect phenylephrine-mediated contractions in Marfan aortae, although they did respond to the thromboxane analogue, U46619. From 6 months on, phenylephrine-induced secretion of prostacyclin and thromboxane A(2) in Marfan aortae was 200% and 40%, respectively, of those in controls. Reduced COX-1 expression was detected in Marfan aortae at 3 and 9 months, whilst COX-2 expression was increased from 3 months on.. The compromised vasomotor function in Marfan thoracic aortae is associated with an imbalanced synthesis of thromboxane A(2) and prostacyclin resulting from the differential protein expression of COX-1 and COX-2.

Topics: Age Factors; Alleles; Animals; Aorta, Thoracic; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase Inhibitors; Disease Models, Animal; Epoprostenol; Fibrillin-1; Fibrillins; Gene Expression Regulation; Heterozygote; Isometric Contraction; Marfan Syndrome; Mice; Mice, Inbred C57BL; Microfilament Proteins; Muscle Contraction; Muscle, Smooth, Vascular; Mutation; Phenylephrine; Thromboxane A2

1.-- In the rat, a fructose-enriched diet induces hyperglycaemia, hypertriglyceridaemia, insulin resistance and hypertension; a model which resembles the human metabolic syndrome. 2.-- Prostanoids, metabolites of arachidonic acid, include vasoactive substances synthesized and released from the vascular wall that have been implicated in the increase of peripheral resistance, one of the mechanisms involved in the fructose-induced hypertension. 3.-- The aim of the present study was to: (i) analyse the effects of the in vitro incubation with fructose on the production and release of prostanoids in rat thoracic aorta and in rat mesenteric bed and (ii) compare the effects of incubation with those of the in vivo acute and chronic treatment of rats with fructose and with the combination of both in vivo and in vitro procedures. 4.-- Blood pressure, glycaemia and triglyceridaemia were significantly elevated in both 4- and 22-week fructose-treated groups. Meanwhile, body and heart weight as well as insulinaemia were similar between experimental animals and controls. 5.-- In aortae, 4 weeks of Fructose treatment did not modify the prostanoid pattern release, but in vitro incubation decreased prostacyclin (PGI(2)) production. However, after 22 weeks, fructose treatment and incubation exerted the same effect. 6.-- In mesenteric bed, after 4 weeks, the incubation and the combination of both procedures reduced the release of the vasodilators PGI(2) and PGE(2), while fructose treatment only diminished the PGE(2) release. On the contrary, the production of the vasoconstrictor thromboxane A(2) (TXA(2)) was enhanced by incubation and both the procedures. After 22 weeks, fructose treatment increased PGI(2) release, while it was reduced by incubation. The combination of both did not modify this peripheral resistance when compared with controls. Finally, incubation of tissues from treated rats increased the release of the vasoconstrictors, PGF(2alpha) and TXA(2). 7.-- In conclusion, the mesenteric bed, a resistance vascular bed, seems to be more sensitive than the aorta, a conductance vessel, to the effects of fructose on prostanoid production. This difference could be related to a more relevant role of resistance vessels in the regulation of peripheral resistance and consequently of blood pressure. The observed effects should contribute to a shift in the balance of the release of prostanoid in favour of vasoconstrictor metabolites. This phenomenon could be related to an increa

Topics: 6-Ketoprostaglandin F1 alpha; Administration, Oral; Animals; Aorta, Thoracic; Blood Pressure; Dinoprostone; Disease Models, Animal; Fructose; Hypertension; In Vitro Techniques; Male; Mesenteric Arteries; Mesenteric Veins; Metabolic Syndrome; Prostaglandins; Rats; Rats, Sprague-Dawley; Thromboxane A2

To investigate the protective effects of the integrated traditional Chinese and western medicine Xuebijing injection on stress-induced organ damage in rabbits.. Forty rabbits were randomly divided into four groups: the control group, the model group, the western medicine group, and the Xuebijing group. The stress-induced organ damage model was replicated by soak the rabbits in water, the animals in the western medicine group and Xuebijing group received injection of lytic cocktail and Xuebijing, respectively. The changes in cortisol (Cor), thromboxane A(2) (TXA(2)), endothelin (ET), nitric oxide synthase (NOS) were determined at different time points in all the groups. The pathologic changes of the gastric mucosa, the adrenal gland and the cardiac muscle cell were observed.. The content of Cor increased significantly in model group (P<0.01). The content of Cor decreased in the western medicine group and Xuebijing group, the changes showed no significant difference between two groups (P>0.05). The contents of ET, TXA(2) decreased and NOS increased in Xuebijing group compared with the western medicine group, the differences were significant (all P<0.05). The pathological changes of the gastric mucosa, the adrenal gland and the cardiac myocyte were less marked in Xuebijing group, compared with the western medicine group, the difference was significant (P<0.05).. Xuebijing has better protective effects on stress-induced organ damage.

Topics: Adrenal Glands; Animals; Disease Models, Animal; Drugs, Chinese Herbal; Endothelins; Gastric Mucosa; Hydrocortisone; Myocytes, Cardiac; Nitric Oxide Synthase; Rabbits; Random Allocation; Stress, Physiological; Thromboxane A2

Licofelone is an analogue of arachidonic acid that inhibits 5-lipoxygenase (LOX), cyclooxygenase (COX)-1 and COX-2. We investigated the effects of licofelone on cardiovascular derangements and production of thromboxane (Tx)A(2) induced by the inflammatory agonist n-formyl-methionyl-leucyl-phenylalanine (fMLP) in the rabbit, in comparison with those of aspirin or rofecoxib, inhibitors of COX-1 and COX-2, respectively. In control rabbits, injection of fMLP (30 nmol/kg) in the jugular vein evokes ischemic electrocardiographic (ECG) changes in the first 1-5 min, i.e. a profound depression of the ST segment and inversion of the T wave. Simultaneously, fMLP induces bradycardia and hypotension and increases TxB(2) blood levels. All changes are transient. Licofelone (60 mg/kg/5 days, p.os) prevented fMLP-induced ECG ischemic changes in all treated animals, reverted bradycardia and hypotension, and significantly reduced TxB(2). Aspirin (10 mg/kg/5 days, p.os) prevented ischemic ECG alterations in 2 out of 5 treated animals and did not modify either bradycardia or hypotension. One rabbit died two min after fMLP. In 2 rabbits, aspirin reduced TxB(2) levels by more than 80% respect to mean control values; the remaining two rabbits produced an amount of TxB(2) similar to controls. These two rabbits also showed ischemic ECG changes. Rofecoxib (10 mg/kg/5 days, p.os) did not prevent fMLP-induced ischemic ECG alteration, bradycardia and hypotension, and did not significantly modify the increase of TxB(2). These results indicate that the capacity of licofelone to efficiently suppress TxA(2) production, is responsible for the protection from the cardiovascular derangement triggered by an inflammatory stimulus.

Topics: Acetates; Animals; Aspirin; Blood Pressure; Cyclooxygenase Inhibitors; Disease Models, Animal; Electrocardiography; Heart Rate; Inflammation; Lactones; Leukotriene B4; Lipoxygenase Inhibitors; Male; Myocardial Ischemia; N-Formylmethionine Leucyl-Phenylalanine; Pyrroles; Rabbits; Sulfones; Thromboxane A2; Time Factors

Although thromboxane (TX)A2 is involved in allergic rhinitis, the mechanisms inducing nasal blockage have not been elucidated. We evaluated the roles of nasal mucosal vascular changes following intranasal instillation of the TXA2 analog U-46619 or leukotriene (LT)D4 to induce nasal blockage in a guinea pig model of allergic rhinitis. Both U-46619- and LTD4-induced nasal blockages in sensitized animals were swiftly and completely suppressed by a vasoconstrictor, naphazoline. The nitric oxide synthase inhibitor N(omega)-nitro-l-arginine methyl ester relieved LTD4-induced nasal blockage, but not U-46619-induced nasal blockage. Although both agonists produced vasodilatation of nasal mucosa in vivo, LTD4 caused vasodilatation while U-46619 caused vasoconstriction in vitro. Both LTD4- and U-46619-induced nasal blockages in vivo should depend on vasodilatation of nasal mucosa. LTD4-induced nasal blockage is induced by direct vasodilatation via nitric oxide. In contrast, U-46619-induced nasal blockage may be associated with contraction of a certain vein that should exist at the exit of capacitance vessels, leading to congestion of the nasal mucosa.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Airway Resistance; Animals; Blood Vessels; Disease Models, Animal; Drug Synergism; Guinea Pigs; Leukotriene D4; Male; Models, Biological; Naphazoline; Nasal Mucosa; Nasal Obstruction; NG-Nitroarginine Methyl Ester; Nitric Oxide; Phenylephrine; Pollen; Rhinitis, Allergic, Seasonal; Thromboxane A2

In the present study, we investigated the role of the central cholinergic system in mediating the pressor effect of intracerebroventricularly administrated U-46619, a thromboxane A2 (TxA2) analog, in hemorrhaged hypotensive rats. Hemorrhage was performed by withdrawing a total volume of 2.1 ml of blood per 100 g body weight over a period of 10 min. Intracerebroventricular (i.c.v.) injection of U-46619 (0.5, 1, 2 micro g) produced a dose- and time-dependent increase in arterial pressure and reversed the hypotension of this condition. Hemorrhage caused small increases in extracellular hypothalamic acetylcholine and choline levels. Intracerebroventricular administration of U-46619 (1 micro g) further increased the levels of extracellular acetylcholine and choline by 57% and 41%, respectively. Pretreatment with SQ-29548 (8 mug; i.c.v.), a selective TxA2 receptor antagonist, completely abrogated the effects of subsequent injection of U-46619 (1 mug; i.c.v.) on arterial pressure and extracellular acetylcholine and choline levels. Pretreatment with mecamylamine (50 micro g; i.c.v.), a cholinergic nonselective nicotinic receptor antagonist, attenuated the pressor effect of U-46619 (1 micro g, i.c.v.) in hemorrhaged rats whereas pretreatment with atropine (10 micro g; i.c.v.), a cholinergic nonselective muscarinic receptor antagonist, had no effect. Interestingly, pretreatment of rats with methyllycaconitine (10 micro g; i.c.v.) or alpha-bungarotoxin (10 micro g; i.c.v.), selective antagonists of alpha-7 subtype nicotinic acetylcholine receptors (alpha7nAChRs), partially abolished the pressor effect of U-46619 (1 micro g; i.c.v.) in the hypotensive condition. Pretreatment with a combination of mecamylamine plus methyllycaconitine or mecamylamine plus alpha-bungarotoxin attenuated the reversal effect of U-46619, but only to the same extent as pretreatment with either antagonist alone. In conclusion, i.c.v. administration of U-46619 restores arterial pressure and increases posterior hypothalamic acetylcholine and choline levels by activating central TxA2 receptors in hemorrhaged hypotensive rats. The activation of central nicotinic cholinergic receptors, predominantly alpha7nAChRs, partially acts as a mediator in the pressor responses to i.c.v. injection of U-46619 under these conditions.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Acetylcholine; alpha7 Nicotinic Acetylcholine Receptor; Animals; Blood Pressure; Bridged Bicyclo Compounds, Heterocyclic; Cholinergic Fibers; Disease Models, Animal; Dose-Response Relationship, Drug; Extracellular Fluid; Fatty Acids, Unsaturated; Hemorrhage; Hydrazines; Hypotension; Hypothalamus, Posterior; Injections, Intraventricular; Male; Neural Pathways; Nicotinic Antagonists; Rats; Rats, Sprague-Dawley; Receptors, Nicotinic; Receptors, Thromboxane A2, Prostaglandin H2; Thromboxane A2; Time Factors; Vasoconstrictor Agents

Intrauterine growth retardation (IUGR) is an important cause of prenatal and neonatal morbidity, and neurologic abnormalities. Although several animal models of IUGR have been developed for scientific investigation, few models approximate the pathophysiology in human fetal growth failure resulting from pregnancy-induced hypertension and preeclampsia. We developed an animal model of IUGR in which fetal growth restriction was induced by administering a synthetic thromboxane A(2) analogue (STA(2)) to the mother.. Timed pregnant Sprague-Dawley rats were used in this study. STA(2) was delivered into the peritoneal cavity of the pregnant female at a rate of 20 ng/h from day 13 of pregnancy. The effectiveness of this model was evaluated by monitoring the overall growth of the fetuses and neonates and measuring the weight and biochemical composition of individual organs.. Fetuses and neonates from the STA(2) group showed a highly significant weight reduction throughout the observation period from day 19 of gestation to postnatal day 7. Weight reduction near and at term exceeded 10% and became more pronounced during the first week after birth. Fetuses on the 20th gestational day exhibited a pattern of growth retardation characteristic of asymmetrical IUGR in which the weight reduction was prominent in the liver with relative sparing of the brain. However, the decrease in brain weight was more than 10%. The protein, DNA, and RNA contents of the liver were lower in the STA(2) group. The protein content of the forebrain and brainstem also decreased significantly in the STA(2) group compared with the control; however, the DNA content of the forebrain was higher in the STA(2) group.. This animal model may mimic human IUGR more closely than previous models because the growth restriction is induced in a truly chronic manner.

Topics: Animals; Disease Models, Animal; Female; Fetal Development; Fetal Growth Retardation; Infusions, Parenteral; Pregnancy; Rats; Rats, Sprague-Dawley; Thromboxane A2

Neutrophil elastase (NE) is a factor that aggravates colitis. We investigated the influence of thromboxane A2 (TXA2) and leukotriene B4 (LTB4) on NE release in Syrian hamsters with trinitrobenzene sulfonic acid-induced colitis. Colonic specimens with colitis were incubated with U-46619 (a TXA2 analogue) or LTB4 in vitro and NE release was examined. As a result, U-46619 increased NE release, while LTB4 had no effect. The NE release induced by U-46619 was inhibited by a TP-receptor antagonist. To demonstrate that TXA2 caused NE release in vivo as well, while LTB4 did not, colitis animals were treated with nordihydroguaiaretic acid (NDGA), a dual inhibitor of cyclooxygenase/lipoxygenase; and colonic luminal TXB(A)2 and LTB4 levels and NE activity were determined. The TXB(A)2 level was significantly correlated with NE activity, while no correlation was found between LTB4 and NE activity. An inhibitory effect of NDGA on the ulcer area was also observed, and NE activity was significantly correlated with the ulcer area. The suppression of TXA2 production by NDGA may result in the inhibition of NE release so that colonic tissue damage becomes less severe. Regulation of NE release is a new biological action of TXA2 that has not been reported before.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Colitis; Cricetinae; Disease Models, Animal; Leukocyte Elastase; Leukotriene B4; Male; Mesocricetus; Specific Pathogen-Free Organisms; Thromboxane A2; Trinitrobenzenesulfonic Acid; Up-Regulation

The pathogenesis of hypertension has been associated with endothelial dysfunction and oxidative stress. We have previously shown that palm oil (PO), with an unsaturated-to-saturated fatty acid ratio close to one and rich in antioxidants vitamins, reduces oxidative stress-induced hypertension in normal rats. Here, we investigated the cardiovascular effects of natural vitamin-rich PO using the Dahl Salt-sensitive hypertension model. Male rats were fed either a high salt (8%NaCl, HS) or low salt (0.3% NaCl, LS) diet with or without PO (Carotino, 5 g/kg daily) for four weeks. Mean arterial pressure (MAP), heart rate, blood flow and vascular resistance, vascular reactivity in vitro as well as remodelling of second-order mesenteric arteries were measured. Plasma levels of nitric oxide (NO), prostacyclin, thromboxane A(2) (TXA(2)) and isoprostane (ISO), were determined by enzyme immunoassay. Plasma, heart and kidney GSH and GSSG levels were analyzed by HPLC and aortic superoxide ((.)O(2)-) production by fluorescence spectrometry. High salt induced an elevation in MAP that was associated with decreased NO, prostacyclin and GSH: GSSG ratio. Plasma ISO and TXA(2), aortic and renal vascular resistance as well as aortic (.)O(2)- were increased. Palm oil reduced MAP, plasma TXA(2) and vascular resistance of the renal and aortic arteries, and increased the GSH: GSSG ratio and NO in the LS group. The HS-induced elevation in ISO and (.)O(2)- production and the reductions in kidney GSH: GSSG ratio, were attenuated by PO. The effect of PO was also associated with a reduced vessel wall-thickness: lumen diameter ratio and a greater relaxant effect of mesenteric arteries to acetylcholine, in the LS group. The mortality associated with HS was reduced by PO. Thus, palm oil attenuates the progression of salt-induced hypertension and mortality, via mechanisms involving modulation of endothelial function and reduction in oxidative stress.

Topics: Animals; Blood Pressure; Disease Models, Animal; Dose-Response Relationship, Drug; Endothelium, Vascular; Glutathione; Hypertension; Immunoenzyme Techniques; Isoprostanes; Male; Nitric Oxide; Oxidative Stress; Palm Oil; Plant Oils; Prostaglandins I; Random Allocation; Rats; Rats, Sprague-Dawley; Sodium Chloride, Dietary; Thromboxane A2; Vascular Resistance

1. In the present study, we aimed to determine the involvement of brain thromboxane A2 (TXA2) in blood pressure decreases evoked by acute and/or graded haemorrhage in rats. 2. Sprague-Dawley rats were used throughout the study. Acute haemorrhage was achieved by withdrawing a total volume of 2.1 and 2.5 mL blood/100 g bodyweight over a period of 10 min. A microdialysis study was performed in a hypothalamic area to measure extracellular TXA2 levels. Graded haemorrhage was conducted successively by withdrawing carotid arterial blood (0.55 mL/100 g bodyweight) over a 10 s period four times (S1-S4) at 5 min intervals. Furegrelate (125, 250 and 500 microg), a TXA2 synthase inhibitor, was injected intracerebroventricularly (i.c.v.) 60 min before acute or graded haemorrhage was initiated. U-46619 (0.5, 1 and 2 microg, i.c.v.), a synthetic TXA2 analogue, was administered 5 min before acute haemorrhage (2.1 mL/100 g bodyweight). 3. Acute haemorrhage produced a severe and long-lasting decrease in blood pressure and had a tendency to increase heart rate. Both haemorrhage protocols (2.1 or 2.5 mL/100 g) generated similar approximate twofold increases in extracellular hypothalamic TXA2 levels. Intracerebroventricular furegrelate (250 microg) pretreatment completely blocked the TXA2 increases induced by acute haemorrhage. Furegrelate administration (100, 250 and 500 microg, i.c.v.) attenuated the fall in arterial pressure evoked by acute haemorrhage and caused significant increases in heart rate at all doses injected. 4. Graded haemorrhage progressively lowered arterial pressure and increased plasma vasopressin and adrenaline levels in the last period. Furegrelate-injected rats were greatly resistant to the hypotensive effect of haemorrhage for all degrees of blood removed. Plasma adrenaline and vasopressin levels were significantly elevated in furegrelate-pretreated rats compared with the saline-treated group during S2-S3 and S4, respectively. U-46619 administration caused small but statistically significant decreases in arterial pressure induced by haemorrhage. 4. The results show that acute hypotensive haemorrhage increases extracellular hypothalamic TXA2 levels. The increase in brain endogenous TXA2 levels involves a decrease in blood pressure evoked by haemorrhage because the blockade of TXA2 synthesis by furegrelate pretreatment attenuated the haemorrhagic hypotension. Increases in plasma adrenaline and vasopressin levels may mediate this effect.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Benzofurans; Blood Pressure; Disease Models, Animal; Epinephrine; Heart Rate; Hemorrhage; Hypotension; Hypothalamus; Injections, Intraventricular; Male; Rats; Rats, Sprague-Dawley; Thromboxane A2; Thromboxane-A Synthase; Time Factors; Vasoconstrictor Agents; Vasopressins

We investigated the effects of a dual thromboxane (TX)A2 synthase inhibitor and TXA2 receptor antagonist (BM-573) on right ventricular-arterial coupling in a porcine model of endotoxic shock. Thirty minutes before the onset of 0.5 mg/kg endotoxin infusion, six pigs (Endo group) received an infusion with a placebo solution, and six other pigs (Anta group) with BM-573. Right ventricular pressure-volume loops were obtained by the conductance catheter technique. The slope (Ees) of the end-systolic pressure-volume relationship and its volume intercept at 25 mmHg were calculated as measures of right ventricular systolic function. RV afterload was quantified by pulmonary arterial elastance (Ea), and Ees/Ea ratio represented right ventricular-arterial coupling. Mechanical efficiency was defined as the ratio of stroke work and pressure-volume area. In this model of endotoxic shock, BM-573 blunted the early phase of pulmonary hypertension, improved arterial oxygenation, and prevented a decrease in right ventricular myocardial efficiency and right ventricular dilatation. However, the drug could not prevent the loss of homeometric regulation and alterations in right ventricular-arterial coupling. In conclusion, dual TXA2 synthase inhibitor and receptor antagonists such as BM-573 have potential therapeutic applications, improving right ventricular efficiency and arterial oxygenation in endotoxic shock.

Topics: Animals; Catheterization; Disease Models, Animal; Endotoxins; Female; Heart Ventricles; Male; Myocardium; Oxygen; Pancreatic Elastase; Placebos; Pressure; Pulmonary Circulation; Shock, Septic; Swine; Systole; Thromboxane A2; Time Factors

This study was designed to investigate the role of eicosanoids, thromboxane A2 (TXA2) and prostacyclin (PGI2) as well as their relationship with endothelin-1 (ET-1) in the pathogenesis of renal parenchymal hypertension. Uremic rats were prepared by renal mass ablation and compared with sham-operated controls. The stable metabolites of TXA2 (TXB2) and PGI2 (6-keto-PGF1alpha) and immunoreactive ET-1 concentrations were measured by specific RIAs in biological fluids and in vascular and renal tissues. To investigate the functional role of TXA2 in the progression of hypertension and renal failure, a group of uremic rats were treated with ridogrel (25 mg/kg/day), a TXA2 synthase inhibitor and receptor antagonist. Renal preproET-1 expression was assessed by Northern blot analysis. Systolic blood pressure (SBP), serum creatinine and proteinuria were found to be higher in uremic rats as compared to sham-operated controls (P < 0.01). TXB2 and ET-1 concentrations were increased in blood vessels, the renal cortex and in urine (P < 0.05). 6-keto-PGF1alpha concentrations were also increased in blood vessels and the renal cortex but decreased in urine (P < 0.05). Ridogrel significantly lowered SBP and proteinuria (P < 0.05) and blunted the increase of serum creatinine. Treatment with ridogrel resulted in a marked fall in vascular, renal and urine TXA2 concentrations, while ET-1 and 6-keto-PGF1alpha concentrations remained unchanged. The preproET-1 expression was higher in uremic rats than in the controls and was unaffected by ridogrel. These results suggest that TXA2 is involved in the pathogenesis of hypertension and renal failure progression in rats with subtotal 5/6 nephrectomy and that this effect is independent of the ET-1 system.

Topics: Animals; Blood Pressure; Disease Models, Animal; Disease Progression; Eicosanoids; Endothelin-1; Epoprostenol; Male; Rats; Rats, Wistar; Renal Insufficiency; Thromboxane A2; Time Factors; Uremia

The aim of this study was to characterize the in vivo pharmacokinetics with the enterohepatic circulation (EHC) and identify the role of multidrug resistance-associated protein 2 (MRP2/Mrp2) in biliary excretion and absorption of ramatroban, a thromboxane A2 antagonist using a recirculatory model.. Ramatroban was intravenously or orally administered to Sprague-Dawley rats (SDR) and Eisai hyperbilirubinemic rats (EHBR). Portal and systemic blood and bile samples were collected, and the drug concentrations were analyzed by high-performance liquid chromatography (HPLC) to estimate various global and local moments.. The bioavailability (BA) of ramatroban was estimated at 21.0% in SDR and 61.9% in EHBR. The local absorption ratio for the dosage after oral administration (Fa(dosage)) and the single-pass local absorption ratio for EHC (Fa') in the rats were similar and nearly 100%. The hepatic recovery ratio (Fh) and the single-pass biliary excretion ratio through the liver for the sum of ramatroban and its glucuronides (Fb) in EHBR were 61.4% and 8.88%, respectively, which differed considerably from those in SDR (15.0% and 22.4%). The difference in hepatic elimination between these strains would be caused, at least in part, by the reduced biliary excretion in EHBR, although the biliary excretion was not completely impaired.. Ramatroban may be excreted by multiple transport systems, followed by efficient enterohepatic reabsorption in both strains. The results suggest that ramatroban may not be susceptible to drug-drug interaction involving MRP2/Mrp2 in biliary excretion and absorption.

Topics: Administration, Oral; Animals; Animals, Genetically Modified; Bile; Carbazoles; Disease Models, Animal; Enterohepatic Circulation; Glucuronides; Hyperbilirubinemia; Injections, Intravenous; Membrane Transport Proteins; Metabolic Clearance Rate; Multidrug Resistance-Associated Protein 2; Multidrug Resistance-Associated Proteins; Rats; Rats, Sprague-Dawley; Receptors, Thromboxane A2, Prostaglandin H2; Species Specificity; Sulfonamides; Thromboxane A2

In the passive Heymann nephritis (PHN) model of rat membranous nephropathy, complement induces glomerular epithelial cell injury and proteinuria, which is partially mediated by eicosanoids. Glomerular cyclooxygenase (COX)-1 and -2 are up-regulated in PHN and contribute to prostanoid generation. In the current study, we address the role of COX isoforms in proteinuria, using the nonselective COX inhibitor indomethacin and the COX-2-selective inhibitor 5,5-dimethyl-3-(3-fluorophenyl)-4-(4-methylsulphonyl)phenyl-2(5H)-furanone (DFU). Four groups of rats with PHN were treated twice daily, from day 7 through 14 with vehicle, 1 mg/kg DFU, 10 mg/kg DFU, or 2 mg/kg indomethacin. Vehicle-treated rats with PHN showed significant proteinuria on day 14 (163 +/- 15 mg/d, n = 19), compared with normal rats (10 +/- 4 mg/d, n = 3, p < 0.001). Treatment with DFU (1 or 10 mg/kg) reduced proteinuria significantly (by ~33%), compared with vehicle, but to a lesser extent than indomethacin (56% reduction). Glomerular eicosanoid generation was reduced significantly in the DFU and indomethacin groups, compared with vehicle. There were no significant differences among vehicle- or DFU-treated groups in [(3)H]inulin clearance, or in glomerular expression of COX-1 and -2. DFU did not affect the autologous immune response. In cultured rat glomerular epithelial cells, COX inhibition reduced complement-induced cytotoxicity, and this reduction was reversed by the thromboxane A(2) analog 9,11-dideoxy-9alpha,11alpha-methanoepoxyprostaglandin F(2alpha) (U46619). Thus, in experimental membranous nephropathy, selective inhibition of COX-2 reduces proteinuria, without adversely affecting renal function. However, inhibition of both COX-1 and -2 is required to achieve a maximum cytoprotective and antiproteinuric effect.

Topics: Actins; Animals; Complement System Proteins; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Disease Models, Animal; Eicosanoids; Epithelial Cells; Furans; Glomerular Filtration Rate; Glomerular Mesangium; Glomerulonephritis; Immunoglobulin G; Indomethacin; Isoenzymes; Male; Membrane Proteins; Prostaglandin-Endoperoxide Synthases; Prostaglandins; Proteinuria; Rats; Rats, Sprague-Dawley; Thromboxane A2

The interaction between angiotensin-(1-7) [Ang-(1-7)] and bradykinin (BK) was studied in the isolated mesenteric arteriolar bed of control and diabetic rats perfused with either 5.5 or 22 mM of glucose. Prostanoids release after the administration of BK, Ang-(1-7) and Ang-(1-7)+BK was also studied. In control and diabetic preparations perfused with Krebs Henseleit solution with 5.5mM of glucose, Ang-(1-7) potentiates BK-induced vasodilation. On the other hand, the potentiating effect disappeared in control and diabetic preparations perfused with 22 mM of glucose. Prostaglandin F(2alpha) (PGF(2alpha)) release induced by BK and Ang-(1-7)+BK was increased in perfusates of diabetic preparations containing 22 mM of glucose. The release of thromboxane A(2) (TXA(2)) (measured as TXB(2)) or prostaglandin I(2) (PGI(2)) (measured as 6-keto-PGF(1alpha)) did not differ in control and diabetic preparations perfused with 5.5 and 22 mM of glucose. Our data allow us to suggest that hyperglycemia may be involved in the lack of potentiation in control and diabetic preparations; increase in PGF(2alpha) release, but not other cyclooxygenase products, may explain the absence of potentiation in diabetic preparations.

Topics: Angiotensins; Animals; Blood Glucose; Bradykinin; Dinoprost; Dinoprostone; Disease Models, Animal; Epoprostenol; Hyperglycemia; Male; Mesenteric Arteries; Prostaglandin-Endoperoxide Synthases; Protein Binding; Rats; Rats, Wistar; Thromboxane A2

Hypertension induced by oxidative stress has been demonstrated in normal rats. In the current study, we investigated the effect of the oral AT(1) receptor blocker losartan (10 mmol/kg/day) on oxidative stress, induced by glutathione (GSH) depletion (using buthionine-sulfoximine, BSO, 30 mmol/L/day in the drinking water), in Sprague-Dawley rats.. Mean arterial pressure (MAP) was measured by tail-cuff plethysmography and the plasma levels of total 8-isoprostane, nitric oxide, prostacyclin, thromboxane A(2), angiotensin II, aldosterone, and aortic cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) were determined by enzyme immunoassay. Plasma, heart, and kidney GSH were analyzed by high-performance liquid chromatography. Aortic and renal superoxide production was determined by fluorescence spectrometry.. In the BSO-treated group, MAP, angiotensin II, isoprostane, thromboxane A(2), and superoxide were elevated; whereas prostacyclin, GSH, cAMP, and cGMP were reduced, compared to control. Losartan alone reduced MAP, and increased renal GSH, plasma nitric oxide, angiotensin II, aldosterone, and aortic cGMP. When administered concurrently with BSO, losartan reversed the BSO-induced elevation of MAP, superoxide, and thromboxane A(2) as well as the reduction in prostacyclin and aortic cAMP levels, but did not significantly alter the reduction in GSH or the elevation in angiotensin II and aldosterone.. Losartan attenuates BSO-induced hypertension, which appears to be mediated, in part, by angiotensin II and the prostanoid endothelium-derived factors.

Topics: Aldosterone; Angiotensin II; Animals; Antihypertensive Agents; Aorta; Biomarkers; Blood Pressure; Buthionine Sulfoximine; Cyclic AMP; Cyclic GMP; Dinoprost; Disease Models, Animal; Enzyme Inhibitors; Epoprostenol; F2-Isoprostanes; Glutathione; Heart Rate; Hypertension; Kidney; Losartan; Male; Models, Cardiovascular; Nitric Oxide; Oxidative Stress; Rats; Rats, Sprague-Dawley; Superoxides; Thromboxane A2; Treatment Outcome

Epidemiological studies link acute infection of the respiratory tract to a transient increased risk of acute myocardial infarction. The underlying mechanisms remain unknown. We hypothesized that vasoactive mediators produced by inflammatory cells in the lungs and drained in the coronary circulation may trigger acute myocardial ischemia. To test this hypothesis we used an experimental model in the rabbit. Injection of the bacterial-derived peptide N-formyl-Met-Leu-Phe (or N-formyl-Methionyl-Leucyl-Phenylalanine)(fMLP) in the jugular vein induced massive recruitment of both polymorphonuclear leukocytes (PMN) and platelets in the microcirculation of the lungs, accompanied by rapid and marked increase of leukotriene B4, cysteinyl leukotrienes and thromboxane (Tx) A2 in the aortic blood. In all animals, fMLP evoked ischemic electrocardiographic changes: within the first minute of infusion a profound depression of the ST segment and inversion of the T wave were observed. Mean aortic pressure and heart rate fell to 64.0 +/- 6.9 and 83.5 +/- 3.1% of the basal levels at 3 and 10 min, respectively. All these alterations were transient. Aspirin, prevented electrocardiographic ischemic changes, reverted bradycardia and hypotension but did not significantly modify either PMN or platelet recruitment nor leukotriene synthesis. Ridogrel, a Tx-synthase and receptor inhibitor, prevented ECG alterations and bradycardia, but did not prevent and even worsened hypotension; it blocked platelet, but not PMN, sequestration. Pretreatment of animals with intravenous high dose of aspirin prevented ridogrel-dependent hypotension and platelet inhibition, suggesting that PGI2 contributes to the effects of Tx-synthase and receptor inhibitor. In hypercholesterolemic rabbits, ECG alterations persisted longer than in normal controls. In summary, our results indicate that acute activation of PMN and platelets in the lungs provokes transient myocardial ischemia, in normal animals that is exacerbated in hypercholesterolemic rabbits. TxA2 appears to be the major mediator of this phenomenon. Moreover the data suggest that a balance between TxA2 and PGI2 plays a pivotal role in platelet activation and recruitment in our model.

Topics: Acute Disease; Animals; Arteriosclerosis; Disease Models, Animal; Electrocardiography; Epoprostenol; Inflammation Mediators; Male; Myocardial Ischemia; N-Formylmethionine Leucyl-Phenylalanine; Platelet Activation; Pneumonia; Rabbits; Thromboxane A2

To investigate the protective effects and mechanism of action of aspirin on focal cerebral ischemia-reperfusion rats.. The right middle cerebral artery of the rat was occluded by inserting a thread through internal carotid artery for 2 h, and then reperfused for 24 h. Different doses of aspirin were intragastricly administrated at reperfusion 0 h and 6 h. The injured area of the brain and cerebral edema were estimated. The contents of prostacyclin (PGI2), thromboxane (TXA2), and endothelin (ET) in plasma were measured by 125I radioimmunoassay method. The content of nitric oxide (NO) in plasma was measured by the nitrate reductase method. The malondialdehyde (MDA) content in brain tissue was determined by the thiobarbituric acid method. The superoxide dismutase content (SOD) in brain tissue was assayed by the xanthine oxidase method. The content of adenosin 5'-triphosphate (ATP) in brain tissue was separated by capillary electrophoresis.. The injured area of the brain and the cerebral edema of occluded side were dramatically reduced after 6 and 60 mg.kg-1 doses of aspirin were administrated intragastricaly. The ratio of PGI2/TXA2 in plasma was increased by aspirin in a dose-dependent manner. In brain tissue of the occluded side, the MDA content was reduced from 9.0 +/- 0.75 to 6.48 +/- 0.74, and the ATP level was increased from 10.26 +/- 1.02 to 25.65 +/- 3.45 by the 60 mg.kg-1 dose of aspirin. No significant effect on SOD content was observed. In plasma, the NO content was significantly decreased from 24.76 +/- 1.88 to 8.17 +/- 0.79, and the ET level was increased from 254.85 +/- 21.14 to 278.43 +/- 16.79 by 6 mg.kg-1 dose of aspirin.. The neuroprotective effects of aspirin on focal cerebral ischemia-reperfusion rats might be attributed to its effects by increasing the ratio of PGI2 and TXA2, reducing lipid peroxides and improving the energy metabolism.

Topics: Animals; Aspirin; Brain Ischemia; Disease Models, Animal; Epoprostenol; Male; Malondialdehyde; Neuroprotective Agents; Random Allocation; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Superoxide Dismutase; Thromboxane A2

Oxidative stress, associated with increased plasma isoprostane (ISO) and reductions in plasma glutathione (GSH), has been shown to cause severe hypertension in normal rats. Palm oil (PO), with an unsaturated-to-saturated fatty acid ratio close to one and rich in antioxidant vitamins, has been investigated for its beneficial effects on arterial thrombosis and atherosclerosis. In this study, the effect of PO on oxidative stress induced by inhibition of GSH synthesis (using buthionine sulfoximine [BSO]) was examined.. Sprague-Dawley rats were separated into two groups and received either natural vitamin-rich PO (Carotino, 5 g/kg daily) or water by gavage. After 4 weeks, they were further divided between receiving either BSO (30 mmol/L/day in the drinking water) or drug-free water for an additional week. Mean arterial pressure (MAP), heart rate (HR), and body weight (BW) were measured before and weekly during the experiment. The levels of plasma ISO, nitric oxide (NO), prostacyclin (PGI2), and thromboxane A2 (TXA2) were determined by enzyme immunoassay, and plasma, heart, and kidney GSH by high-performance liquid chromatography.. The PO reduced the age-dependent increase in MAP, and the pressor response to BSO, without changing the HR or BW compared to the BSO and control groups. It also elevated PGI2, NO, and aortic cGMP, but decreased TXA2 and aortic cAMP. In addition, the BSO-induced increase in ISO and TXA2, and the reduction in kidney GSH were attenuated by PO. However, the PO effect on NO, PGI2, cGMP, and TXA2 was partly counteracted by BSO.. Palm oil reduces BSO-induced oxidative stress and attenuates hypertension by mechanisms involving changes in endothelium-derived factors.

Topics: Animals; Buthionine Sulfoximine; Computer Graphics; Disease Models, Animal; Endothelium, Vascular; Enzyme Inhibitors; Epoprostenol; Glutathione; Hypertension; Immunoenzyme Techniques; Isoprostanes; Nitric Oxide; Oxidative Stress; Palm Oil; Plant Oils; Rats; Rats, Sprague-Dawley; Thromboxane A2

The purpose of this study was to determine the role of thromboxane A2 (TXA2) in a conscious, chronically instrumented rat model of pregnancy-induced hypertension (PIH) produced by chronic reductions in uterine perfusion pressure (RUPP).. Mean arterial pressure (MAP), glomerular filtration rate (GFR), effective renal plasma flow (ERPF) and 24-h urinary excretion of TXB2 (metabolite of TXA2) were determined in normal pregnant rats and RUPP pregnant rats.. At day 20 of pregnancy, RUPP rats showed a significantly (P < .05) higher MAP (125 +/- 3 mm Hg v 100 +/- 2 mm Hg) as compared with normal pregnant controls. The elevation in arterial pressure in RUPP group was associated with a marked increase (P < .05) in the urinary concentration of TXB2 compared with normal pregnant group (3663 +/- 488 v 2646 +/- 257 pg/24 h). Baseline GFR (1.74 +/- 0.13 v 2.40 +/- 0.20 mL/min, respectively, P < .05) and ERPF (5.13 +/- 0.44 v 6.44 +/- 0.58 mL/min, respectively) were decreased in RUPP rats relative to pregnant controls. Infusion of a TX receptor antagonist, SQ 29,548 (2 mg/kg bolus plus 2 mg/kg per h infusion) had no significant effect on increased MAP in RUPP pregnant rats. Similarly, ERPF and GFR did not change during acute blockade of TXA2 receptors in this group.. These findings suggest that enhanced production of TXA2 does not play a major role in mediating the hypertension and renal vasoconstriction produced by chronic RUPP in pregnant rats.

Topics: Animals; Bridged Bicyclo Compounds, Heterocyclic; Disease Models, Animal; Fatty Acids, Unsaturated; Female; Hydrazines; Hypertension; Pre-Eclampsia; Pregnancy; Pregnancy Complications, Cardiovascular; Rats; Renal Circulation; Thromboxane A2; Uterus

The study was undertaken to develop a coronary microvascular spasm model in pigs by repeated epicardial coronary artery endothelial injury.. The pathophysiologic mechanisms responsible for coronary microvascular spasm remain unclear, in large part because a suitable animal model has yet to be found.. Balloon endothelial denudation was done just distal to the site of an implanted Doppler flowmeter in the left anterior descending coronary artery (LAD) every two weeks for a total of four times. Changes in LAD blood flow by intracoronary administration of vasoactive agents were assessed before each denudation.. In the epicardial LAD endothelial denudation pigs, decreases in LAD blood flow caused by acetylcholine were augmented. Before denudation, it was - 15 +/- 4%, and at week 8 (i.e., two weeks after the fourth denudation) it was -100% (i.e., zero flow [p < 0.01]). The LAD flow changes in response to 5-hydroxytryptamine (5-HT) changed from an increase to a decrease, accompanied by medial thickening of microvessels in the LAD perfusion area. These flow responses were observed without significant changes in LAD diameter. In contrast, the LAD blood flow responses to acetylcholine and 5-HT did not change throughout the experiment in pigs given aspirin and a thromboxane A2 (TXA2) synthase inhibitor orally.. This microvascular spasm model indicates that hypersensitivity to vasoactive substances in the microvascular beds as well as microvascular remodeling are brought about partly through TXA2. This model should be useful for examining the pathophysiology and treatment of microvascular angina.

Topics: Animals; Coronary Vasospasm; Coronary Vessels; Disease Models, Animal; Endocardium; Endothelium, Vascular; Microcirculation; Swine; Thromboxane A2

Hyperhomocysteinemia (HHcy) is thought to promote arteriosclerosis and peripheral arterial disease, in part by impairing the function of endothelium. Because flow-induced dilation is mediated by the endothelium, we hypothesized that HHcy alters this response by interfering with the synthesis/action of NO and prostaglandins. Thus, changes in the diameter of isolated, pressurized (at 80 mm Hg) gracilis skeletal muscle arterioles (diameter approximately 170 microm) from control and methionine diet-induced HHcy rats were investigated with videomicroscopy. Increases in intraluminal flow (from 0 to 25 microL/min) resulted in dilations of control arterioles (maximum, 34+/-4 microm). In contrast, increases in flow elicited constrictions of HHcy arterioles (-36+/-3 microm). In control arterioles, the NO synthase inhibitor N:(omega)-nitro-L-arginine-methyl ester significantly attenuated (approximately 50%) dilation, whereas the additional administration of indomethacin, an inhibitor of cyclooxygenase, eliminated flow-induced dilation. In the arterioles of HHcy rats, flow-induced constriction was not affected by N:(omega)-nitro-L-arginine-methyl ester, whereas it was abolished by indomethacin or the prostaglandin H(2)/thromboxane A(2) (TXA(2)) receptor antagonist SQ 29,548 or the TXA(2) synthase inhibitor CGS 13,080. Thus, in HHcy, increases in intraluminal flow elicit constrictions of skeletal muscle arterioles due to the impaired NO and enhanced TXA(2) mediation of the response, alterations that likely contribute to the development of peripheral arterial disease.

Topics: Animals; Arterioles; Constriction, Pathologic; Disease Models, Animal; Endothelium, Vascular; Hyperhomocysteinemia; Male; Nitric Oxide; Rats; Rats, Wistar; Thromboxane A2

Airway hyperresponsiveness (AHR) is one of the characteristic features of human asthma. The presence of AHR and the precise mechanisms immediately after establishment of sensitization in guinea pigs are unclear, although there are many reports showing allergen exposure that causes an increase in bronchial responsiveness associated with eosinophil influx into the airway in sensitized guinea pigs.. We investigated the inhibitory effects on AHR to histamine of ONO-1078, a leukotriene antagonist; indomethacin, a cyclooxygenase inhibitor; S-145, a thromboxane A(2) (TXA(2)) antagonist, and Y-24180, a platelet-activating factor (PAF) antagonist, to assess the involvement of chemical mediators in AHR employing ovalbumin (OA) sensitized guinea pig models.. Male Hartley guinea pigs were used. Each group comprised 4-7 animals. The animals were sensitized to OA, injecting intraperitoneally 30 mg of cyclophosphamide and 2,000 microg of OA together with 100 mg of aluminum hydroxide as the adjuvant. The guinea pigs were artificially ventilated via a cannula using a small-animal respirator after intraperitoneal anesthesia with pentobarbital sodium for tracheotomy. The pressure at the airway opening (PAO) was measured using a differential pressure transducer, and a differential pressure of peak PAO (peak DeltaPAO) at inspiratory phase as an overall index of bronchial response to bronchoactive agents was used. While being artificially ventilated, the animals were exposed to physiological saline solution containing various concentrations of histamine (4.9, 9.8, 20, 39, 78, and 156 microg/ml) by inhalation for 30 s at 3-min intervals. Determinations were made at 1 min after each inhalation. The chemical mediators were each (30 mg/kg of ONO-1078, 3 mg/kg of S-1452, and 1 mg/kg of Y-24180) administered orally to sensitized guinea pigs, and the airway response to histamine was assessed. Each group comprised 4-7 animals.. The airway response to histamine was significantly greater in the sensitized group than in the nonsensitized group at histamine concentrations of 36 (p < 0.05), 78, and 156 mg/ml (p < 0.01). Leukotrienes C(4) and D(4): 30 mg/kg of ONO-178 did not show any inhibitory effect on airway response to inhaled histamine. Cyclooxygenase: 5 mg/kg of indomethacin did not show any inhibitory effect on the airway response to inhaled histamine. TXA(2): the AHR to inhaled histamine at doses of 9.8, 39, 78, and 156 microg/ml was significantly inhibited by prior administration of 3 mg/kg of S-1452. PAF: the AHR to inhaled histamine at doses of 9.8, 39, and 78 microg/ml was significantly inhibited by prior administration of 1 mg/kg of Y-24180.. S-1452 (3 mg/kg) and Y-24180 (1 mg/kg) significantly inhibited AHR to histamine, while ONO-108 (30 mg/kg) and indomethacin (5 mg/kg) did not. The results suggest that TXA(2) and PAF are involved in AHR in OA-sensitized guinea pigs.

Topics: Airway Resistance; Animals; Asthma; Bronchial Hyperreactivity; Disease Models, Animal; Dose-Response Relationship, Drug; Guinea Pigs; Histamine; Indomethacin; Leukotriene C4; Leukotriene D4; Male; Ovalbumin; Platelet Activating Factor; Probability; Reference Values; Sensitivity and Specificity; Thromboxane A2

Acute hemodynamic effects of beraprost sodium were tested in a canine vasoconstrictive pulmonary hypertension model induced by the continuous infusion of U-46619, a thromboxane A(2)mimetic. The effects of beraprost were compared with those of prostaglandin E(1), nitroglycerin and nifedipine. Beraprost and nitroglycerin decreased pulmonary arterial pressure. On the other hand, prostaglandin E(1)and nifedipine increased pulmonary arterial pressure. All drugs except nitroglycerin increased cardiac output and decreased pulmonary vascular resistance. Beraprost was selective to pulmonary circulation, while nitroglycerin, prostaglandin E(1), and nifedipine showed poor selectivity for the pulmonary vasculature. These results suggest that the vasodilative effect of beraprost is the most selective for the pulmonary circulation among these four vasodilators.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Alprostadil; Animals; Antihypertensive Agents; Disease Models, Animal; Dogs; Dose-Response Relationship, Drug; Epoprostenol; Humans; Hypertension, Pulmonary; Male; Nifedipine; Nitroglycerin; Oxygen; Thromboxane A2; Vasoconstrictor Agents; Vasodilator Agents

Biologically active substances, such as prostaglandins, thromboxanes, and leukotrienes, which are metabolites involved in the arachidonic acid cascade, are detected in herniated disc samples obtained from patients with lumbar disc herniation. However, little is known concerning the relationships between these substances and clinical symptoms such as radicular pain. Thromboxane A2 (TXA2) induces not only potent platelet aggregation, but also blood vessel contraction. Leukotriene B4 (LTB4), a potent chemotactic agent, plays a role in inflammatory reactions by recruiting neutrophils and lymphocytes. The purpose of this study was to examine the roles of TXA2 and LTB4 in the hyperalgesia induced by application of nucleus pulposus to the lumbar nerve root in the rat. TXA2 synthetase inhibitor and LTB4 receptor antagonist, which were injected into the epidural space, decreased mechanical hyperalgesia at both three and seven days after epidural injection. There were no significant differences in sensitivity to noxious thermal stimuli following application of the nucleus pulposus or an epidural injection. Epidural injection of LTB4 receptor antagonist and/or TXA2 synthetase inhibitor may attenuate the painful radiculopathy due to lumbar disc herniation. In conclusion, our findings suggest that TXA2 and LTB4 may play significant roles in mechanical hyperalgesia induced by autologous nucleus pulposus.

Topics: Animals; Disease Models, Animal; Enzyme Inhibitors; Hyperalgesia; Intervertebral Disc Displacement; Leukotriene B4; Male; Methacrylates; Motor Activity; Phenylpropionates; Rats; Rats, Sprague-Dawley; Receptors, Leukotriene B4; Shoulder Pain; Thromboxane A2; Thromboxane-A Synthase

Lipid peroxidation and platelet activation are thought to be important contributors to the pathogenesis of atherosclerosis. The relevance of their interaction in vivo, however, is unknown.. LDL receptor-deficient (LDLR(-/-)) mice on a high-fat diet developed extensive atherosclerosis and had increased urinary levels of 8,12-iso-isoprostane (iP) F(2alpha)-VI and 2,3-dinor-thromboxane (Tx) B(2), markers of in vivo lipid peroxidation and platelet activation, respectively. Vitamin E supplementation suppressed 8,12-iso-iPF(2alpha)-VI biosynthesis and reduced atherosclerosis (65%) without having a significant effect on lipid levels or TxB(2) biosynthesis. Addition of the platelet inhibitor indomethacin to vitamin E simultaneously suppressed 8,12-iso-iPF(2alpha)-VI and TxB(2), significantly reduced soluble intercellular adhesion molecule-1 and monocyte chemoattractant protein-1, and remarkably, further reduced atherosclerosis (80%).. These results indicate that in vivo lipid peroxidation and platelet activation coexist in murine atherosclerosis and that lipid peroxidation does not contribute to platelet activation and reflects the oxidant component of the inflammatory response. Our findings suggest that oxidant stress and platelet activation represent 2 distinct therapeutic targets in atherogenesis. We propose that a combination of antioxidants and platelet inhibitors might be rationally evaluated in the prevention of progression of human atherosclerosis.

Topics: Animals; Antioxidants; Aorta; Arteriosclerosis; Cyclooxygenase Inhibitors; Diet, Atherogenic; Dietary Supplements; Dinoprost; Disease Models, Animal; Disease Progression; Female; Immunohistochemistry; Indomethacin; Lipid Peroxidation; Lipids; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Platelet Activation; Receptors, LDL; Thromboxane A2; Thromboxane B2; Vitamin E

Prostaglandin (PG) I(2) and thromboxane (TX) A(2), the most common prostanoids in the cardiovascular system, are produced abundantly during cardiac ischemia/reperfusion (I/R); their roles in I/R injury, however, remain undetermined. We intended to clarify these roles of PGI(2) and TXA(2) using mice lacking the PGI(2) receptor, IP(-/-) mice, or the TXA(2) receptor, TP(-/-) mice.. The left anterior descending coronary artery was occluded for 1 hour and then reperfused for 24 hours. The size of myocardial infarct in IP(-/-) mice was significantly larger than that in wild-type mice, although the size of the area at risk was similar between the 2 groups of mice. In contrast, there was no such difference between TP(-/-) and wild-type mice. To further determine whether PGI(2) and TXA(2) act directly on the cardiac tissue or indirectly through their action on blood constituents, we perfused excised heart according to the Langendorff technique. The isolated heart was then subjected to global ischemia followed by reperfusion. In IP(-/-) mice, developed tension and coronary flow rate during reperfusion were significantly lower and release of creatine kinase was significantly higher than those in wild-type mice. There were no such differences, however, between TP(-/-) and wild-type mice.. PGI(2), which was produced endogenously during cardiac I/R, exerts a protective effect on cardiomyocytes independent of its effects on platelets and neutrophils. In contrast, TXA(2) has little role in the cardiac I/R injury.

Topics: Adenosine Triphosphate; Animals; Blood Flow Velocity; Blood Pressure; Coronary Circulation; Creatine Kinase; Cytoprotection; Disease Models, Animal; Electrocardiography; Epoprostenol; Heart; Heart Rate; In Vitro Techniques; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocardial Ischemia; Myocardial Reperfusion Injury; Myocardium; Receptors, Epoprostenol; Receptors, Prostaglandin; Receptors, Thromboxane; Thromboxane A2

To study the significance of thrombosis after experimental pulmonary thromboembolism (PTE).. Acute PTE models of rabbits were established with injection of autologous blood clots (0.04 g/kg) stabilized in a temperature-controlled (70 degrees C) of distilled water for 10 minutes through the femoral vein, then the regulation of thrombosis was explored at dissection and upon microscopic examination after PTE. Moreover, the coagulability of blood and the plasma level of thromboxane A2(TXA2) and endothelin (ET) were examined.. Thrombotic propensity was found at 1 h, and fresh thrombosis started to form at 24 h following clots infusion. Emboli were completely or partly dissolved at 5 d and organized at 10 and 14 d after clots infused. Prothrombin time was significantly lower [(7.15 +/- 0.06)s], and fibrinogen was higher [(5.86 +/- 1.50) g/L] at 24 h post-clots, compared with pre-clots [(7.34 +/- 0.19)s, (3.37 +/- 1.02) g/L] (P < 0.05). Venous plasma level of TXA2 began to increase at 5 min [(2.5 +/- 0.7) micrograms/L] and continued to rise to its maximum at 15 min [(2.5 +/- 0.6) micrograms/L], then declined at 60 min after clots infusion. The level of ET in both arterial and venous blood increased at 5 d post-clots [(0.84 +/- 0.15) micrograms/L and (0.23 +/- 0.05) micrograms/L] separately, while most of emboli resolved.. There is thrombus formation after autologous-blood-clots-induced PTE. Furthermore, thrombus formation, fibrinolysis and organization may always interact on each other consistently, and control the pathogenesis of PTE. Abnormalities of ET metabolism occur after PTE and the major mediator of TXA2 plays an important role in the early phase of PTE.

Topics: Animals; Disease Models, Animal; Endothelins; Female; Fibrinogen; Lung; Male; Prothrombin Time; Pulmonary Embolism; Rabbits; Thrombosis; Thromboxane A2

Thromboxane (Tx) A2 is a platelet agonist, smooth muscle cell constrictor, and mitogen. Urinary Tx metabolite (Tx-M) excretion is increased in syndromes of platelet activation and early in both normal pregnancies and in pregnancy-induced hypertension. A further increment occurs in patients presenting with severe preeclampsia, in whom Tx-M correlates with other indices of disease severity. TxA2 exerts its effects through a membrane receptor (TP), of which two isoforms (alpha and beta; refs. 5,6) have been cloned. Overexpression of TP in the vasculature under the control of the pre-proendothelin-1 promoter results in a murine model of intrauterine growth retardation (IUGR), which is rescued by timed suppression of Tx synthesis with indomethacin. IUGR is commonly associated with maternal diabetes or cigarette smoking, both conditions associated with increased TxA2 biosynthesis.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Blood Vessels; Disease Models, Animal; Female; Fetal Growth Retardation; Humans; Male; Mice; Receptors, Thromboxane; Thromboxane A2

Dietary supplementation with polyunsaturated fatty acids (PUFAs) alters the course of experimental kidney disease in dogs. In particular, supplementation with omega-6 PUFAs hastens the decline of kidney function, and omega-3 PUFAs are renoprotective. We investigated the early stages of renal insufficiency to determine whether PUFA supplementation altered the magnitude of hypercholesterolemia or glomerular hemodynamics. Two months after 11/12 nephrectomy, dogs were randomly divided into three groups of 6 animals each. Each group of dogs was then fed a low-fat basal diet supplemented with one of three sources of lipid to achieve a final concentration of 15% added fat. Fat sources were rich in omega-3 PUFAs (menhaden fish oil, group FO), omega-6 PUFAs (safflower oil, group SO), or saturated fatty acids (beef tallow, group C). Early in renal insufficiency, before significant kidney damage, group FO had a lower (P<.05) serum cholesterol concentration and tended to have a lower urinary prostaglandin E2 (PGE2) and thromboxane A2 (TxA2) excretion than group C. In contrast, group SO had a higher mean glomerular capillary pressure (P<.05) and more glomerular enlargement (P<.05) and tended to have higher eicosanoid excretion rates than group C. These differences in lipid metabolism, glomerular hypertension and hypertrophy, and urinary eicosanoid metabolism could explain, in part, the beneficial effects of omega-3 PUFAs and the detrimental effects of omega-6 PUFAs when administered on a long-term basis in this model of renal insufficiency.

Topics: Animals; Cholesterol; Dietary Fats, Unsaturated; Dinoprostone; Disease Models, Animal; Dogs; Fatty Acids, Omega-3; Fatty Acids, Omega-6; Fatty Acids, Unsaturated; Female; Hypercholesterolemia; Kidney; Kidney Failure, Chronic; Male; Renal Circulation; Thromboxane A2

Many reports have associated intrauterine growth retardation (IUGR) with adverse neurological outcome, but the underlying pathology is imperfectly understood. We have developed a new rat model of IUGR using maternal administration of synthetic thromboxane A(2) (STA(2)). In the present study, the effect of this insult on neuronal migration in the rat cerebral cortex was examined. Bromodeoxyuridine (BrdU), a time-specific cell marker was administered intraperitoneally to the mothers on embryonic day (E) 19. At postnatal day (P) 3, P4, P5, and P6, pups were terminally anesthetized and brains were removed. BrdU-labeled cells were detected immunohistochemically and counted in cerebrum, which was divided into the cortical plate (CP), the intermediate zone, and the subventricular/ventricular zone (SVZ+VZ). Numbers of labeled cells in the three areas over time were compared between IUGR and control animals. Numbers of labeled cells in SVZ+VZ were significantly greater in IUGR than in controls at P3, 5, and 6 (P<0.05). In contrast, labeled cells in the CP were significantly less abundant in IUGR animals than in controls at P3, 4, and 6 (P<0.05). We concluded that neuronal migration was delayed in IUGR rats.

Topics: Animals; Animals, Newborn; Brain; Cell Movement; Disease Models, Animal; Female; Fetal Growth Retardation; Neurons; Pregnancy; Rats; Rats, Sprague-Dawley; Thromboxane A2

Having developed a non-insulin-dependent diabetes mellitus (NIDDM) syndrome model in the rabbit using Wirsung duct ligation, it appeared interesting to use it to study the relationship between glycemia and the plasma levels of TXA(2)and PGI(2), and of some other biochemical parameters such as cholesterol, triglycerides, alkaline phosphatase and transaminases. A comparative study was carried out in the sham-operated rabbits (controls, C) and those having their pancreatic duct ligatured (NIDDM, D) at 15, 30, 40, 50 and 60 days post-ligation. On the 40th days, whereas in the controls, glycemia was 1.17 +/- 0.04 g.l(-1), it reached a maximum of 4.62 +/- 0.76 g.l(-1)(25.40 mM) in the NIDDMs. No significant modification was observed either in cholesterolemia or in triglyceridemia in either group. The GOT and GPT were highly increased, from 11.50 +/- 4.00 IU. l(-1)and 27.00 +/- 1.50 IU.l(-1)(C) to 37.50 +/- 5.64 IU.l(-1)(P<0. 001) and 58.50 +/- 7.50 IU.l(-1)(D) (P<0.001) in the NIDDM group, suggesting that hyperglycemia occurred simultaneously with the degeneration of the pancreatic tissue. In parallel, in D rabbits, the plasma levels of TXB(2)and 6 keto PGF(1alpha)were augmented to 68.22 +/- 6.20 pg.ml(-1)versus 22.49 +/- 5.74 pg.ml(-1)(C) (P<0.001), and 127.11 +/- 14.39 pg.ml(-1)versus 48.65 +/- 4.51 pg.ml(-1)(C) (P<0. 001) respectively. Statistical studies showed a significant correlation (P<0.05 and <0.02) between glycemia and the biosynthesis of eicosanoids under study. Moreover, 25 mM was found to be the threshold level of glucose excess essential to increase the TXA(2)and PGI(2)biosynthesis significantly. This supports the results obtained by other authors studying the action of glucose on phospholipase activity and consequent eicosanoid production.

Topics: 6-Ketoprostaglandin F1 alpha; Alkaline Phosphatase; Animals; Blood Glucose; Blood Proteins; Cholesterol; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Disease Models, Animal; Epoprostenol; Hyperglycemia; Ligation; Pancreatic Ducts; Platelet Aggregation Inhibitors; Rabbits; Thromboxane A2; Thromboxane B2; Time Factors; Transaminases

Topics: Animals; Aspirin; Cause of Death; Cyclooxygenase Inhibitors; Disease Models, Animal; Humans; Platelet Aggregation Inhibitors; Pulmonary Embolism; Risk Factors; Thromboembolism; Thromboxane A2; Vasoconstrictor Agents

1. The purpose of this study was to investigate the involvement of thromboxane A(2) (TXA(2)) in the cough response in a guinea-pig cough model. Here, we describe results obtained using a selective TXA(2) synthetase inhibitor, ozagrel, and a selective TXA(2) agonist, U-46619. 2. Guinea-pigs were anaesthetized and exposed to an aerosol of capsaicin (100 microM) to elicit coughing. The number of coughs was 20.0+/-5.8 during capsaicin provocation (5 min), but only 2. 8+/-0.4 during a 5-min inhalation of phosphate-buffered saline (PBS) (P:<0.05). 3. TXB(2) levels in BAL were 101.4+/-8.0 and 58.4+/-8.7 pg ml(-1) following capsaicin and PBS inhalation, respectively (P:<0. 01), but there was no intergroup difference in the cell populations in BAL. 4. Inhalation of U-46619 did not induce a cough response by itself at concentrations of 100 ng ml(-1) to 10 microg ml(-1). However, it caused a 2 fold increase in the number of capsaicin-induced coughs. 5. To explore the source of the TXA(2), BAL cells were stimulated with capsaicin and the supernatants collected for analysis. The TXB(2) concentration in BAL was increased dose-dependently, indicating that TXA(2) is released from BAL cells in response to capsaicin. 6. Ozagrel was administered orally 1 h before a 5 min capsaicin provocation and the number of coughs was counted during the capsaicin inhalation. Ozagrel decreased the number of coughs dose-dependently (ED(50) value, 26.3 mg kg(-1)). 7. These results show that TXA(2) modulates the capsaicin-induced cough response by increasing capsaicin-sensitivity.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Antitussive Agents; Capsaicin; Cough; Disease Models, Animal; Dose-Response Relationship, Drug; Guinea Pigs; Male; Methacrylates; Thromboxane A2; Thromboxane-A Synthase

The myogenic response of skeletal muscle arterioles is enhanced in hypertension because of the release of endothelin (ET) and prostaglandin H(2) (PGH(2))/thromboxane A(2) (TxA(2)) from the endothelium. We hypothesized that ET and PGH(2)/TxA(2) modulate Ca(2+) signaling in arteriolar smooth muscle and thereby enhance myogenic constriction. Thus, simultaneous changes in intracellular Ca(2+) concentration in smooth muscle ([Ca(2+)](i)), measured by fura 2 microfluorometry (expressed as Ca(2+) fluorescence ratio [R(Ca)]), and diameter were obtained as a function of intraluminal pressure (P(i)) in isolated cannulated gracilis muscle arterioles (diameter approximately 120 micrometer) of normotensive Wistar rats (WR) and spontaneously hypertensive rats (SHR). In the absence of extracellular Ca(2+), increases in P(i) from 20 to 160 mm Hg increased the passive diameter of arterioles without changes in R(Ca). In the presence of extracellular Ca(2+) and endothelium, increases in P(i) elicited similar increases in R(Ca) (30+/-7% for control and 33+/-8% for SHR at 160 mm Hg) but a significantly (P<0.05) greater constriction of SHR arterioles compared with WR arterioles (at 160 mm Hg, 55+/-4% versus 38+/-2%, respectively, of passive diameter). In the absence of the endothelium, P(i)-induced changes in the R(Ca) and diameter of SHR and WR arterioles did not differ significantly. Also, a step increase in P(i) (from 80 to 140 mm Hg) elicited a similar increase in R(Ca) but greater constrictions in SHR versus WR arterioles. In the presence of the TxA(2) receptor inhibitor SQ29,548 and the ET(A) receptor inhibitor BQ123, there was no difference between responses of SHR and WR arterioles. In WR arterioles, increasing concentrations of KCl elicited a significant increase in R(Ca) (38+/-7% at 80 mmol/L) and completely constricted the arterioles. In contrast, constrictions to ET (52+/-7% at 3x10(-12) mol/L) and the TxA(2) agonist U46619 (40+/-8% at 3x10(-9) mol/L) were not accompanied by increases in R(Ca) at submaximal concentrations. Collectively, these findings suggest that in hypertension, endothelium-derived ET and PGH(2)/TxA(2) increase the Ca(2+) sensitivity of the contractile apparatus of arteriolar smooth muscle; thus, the similar increases in [Ca(2+)](i) in response to the elevation of intraluminal pressure elicit greater myogenic constriction.

Topics: Animals; Arterioles; Calcium; Constriction, Pathologic; Cytophotometry; Disease Models, Animal; Endothelins; Endothelium; Hypertension; Microscopy, Video; Muscle Contraction; Muscle, Smooth, Vascular; Prostaglandin H2; Prostaglandins H; Rats; Rats, Inbred SHR; Rats, Wistar; Thromboxane A2; Vascular Resistance

Thromboxane A(2) is a potent vasoconstrictor and platelet agonist; prostacyclin is a potent platelet inhibitor and vasodilator. Altered biosynthesis of these eicosanoids is a feature of human hypercholesterolemia and atherosclerosis. This study examined whether in 2 murine models of atherosclerosis their levels are increased and correlated with the evolution of the disease. Urinary 2,3-dinor thromboxane B(2) and 2,3-dinor-6-keto prostaglandin F(1 alpha), metabolites of thromboxane and prostacyclin, respectively, were assayed in apoliprotein E (apoE)-deficient mice on chow and low-density lipoprotein receptor (LDLR)-deficient mice on chow and a Western-type diet. Atherosclerosis lesion area was measured by en face method. Both eicosanoids increased in apoE-deficient mice on chow and in LDLR-deficient mice on a high-fat diet, but not in LDLR-deficient mice on chow by the end of the study. Aspirin suppressed ex vivo platelet aggregation, serum thromboxane B(2), and 2,3-dinor thromboxane B(2), and significantly reduced the excretion of 2,3-dinor-6-keto prostaglandin F(1 alpha) in these animals. This study demonstrates that thromboxane as well as prostacyclin biosynthesis is increased in 2 murine models of atherogenesis and is secondary to increased in vivo platelet activation. Assessment of their generation in these models may afford the basis for future studies on the functional role of these eicosanoids in the evolution and progression of atherosclerosis. (Blood. 2000;96:3823-3826)

Topics: Age Factors; Animals; Aorta; Arteriosclerosis; Aspirin; Diet, Atherogenic; Disease Models, Animal; Eicosanoids; Epoprostenol; Female; Hominidae; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Platelet Aggregation; Platelet Aggregation Inhibitors; Prostaglandins F; Receptors, LDL; Thromboxane A2; Thromboxane B2

The study was designed to investigate the effects of acetylcholine (ACh) on pulmonary circulation with special regard to mediators that could be involved in the mediation of ACh-induced effects. ACh has been reported to induce either vasodilation or vasoconstriction in the pulmonary circulation of different species.. Prospective experimental study in rabbits.. Experimental laboratory in a university teaching hospital.. Sixty-six adult rabbits of either sex.. The experiments were performed on 66 isolated and ventilated rabbit lungs that were perfused with a cell- and plasma-free buffer solution. ACh was injected in various concentrations after pulmonary artery preconstriction and in untreated lungs.. Pulmonary arterial pressure (PAP) and lung weight gain were monitored continuously. Perfusate samples were taken intermittently to determine endothelin-1 (ET-1), thromboxane A2 (TXA2), and prostacyclin (PGI2) concentrations. ACh in final dosages from 10(-5) to 10(-2) M (n = 6 each) was injected into the pulmonary artery of lungs treated with U46619 to induce pulmonary arterial hypertension or was injected into untreated lungs. To analyze the potential mechanisms of action, ACh (10(-5) M) was administered in additional experiments after pretreatment with either ETA receptor antagonist BQ123 (10(-6) M; n = 6) or the cyclooxygenase inhibitor diclofenac (10 microg/mL; n = 6). In preconstricted pulmonary vessels, ACh (10(-3) and 10(-2) M) initially induced a PAP rise for 10 mins followed by a sustained decrease. In untreated lungs, ACh induced an immediate dose-dependent increase in PAP, requiring as long as 30 mins to return to predrug levels. Simultaneously, significantly elevated TXA2 and PGI2 levels were observed. Furthermore, ET-1 was detected in the perfusate, which was free from ET-1 before ACh administration. Pretreatment with BQ123 reduced substantially the ACh (10(-5) M)-induced PAP increase and the release of TXA2 and PGI2. At 5 mins, the PAP maximum was reduced from 18.5 +/- 3.2 mm Hg to 9.9 +/- 0.65 mm Hg by BQ123 pretreatment (p < .01). An inhibition of PAP increase was also observed after diclofenac pretreatment (11.6 +/- 0.4 mm Hg at 5 mins; p < .05). Inhibitory effects at 5 mins were significantly more pronounced in the BQ123 group compared with the diclofenac group.. The effects of ACh on the pulmonary circulation of isolated rabbit lungs depend on ACh concentration and the basal tone of the arterial vasculature. In lungs with a normal pulmonary vascular resistance, ACh administration causes vasoconstriction via the release of ET-1 and TXA2, whereas vasodilation is induced in preconstricted pulmonary vessels.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Acetylcholine; Animals; Cyclooxygenase Inhibitors; Diclofenac; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Drug Interactions; Endothelin Receptor Antagonists; Endothelin-1; Female; Hypertension, Pulmonary; In Vitro Techniques; Male; Peptides, Cyclic; Pulmonary Circulation; Pulmonary Wedge Pressure; Rabbits; Thromboxane A2; Vascular Resistance; Vasoconstriction; Vasoconstrictor Agents; Vasodilation

Thromboxane (Tx) A2 is a potent vasoconstrictor eicosanoid that attains high levels within nephritic glomeruli and mediates a drop in glomerular filtration rate (GFR). In the course of nephritis, however, GFR recovers despite high intraglomerular TxA2 levels. We hypothesized that this recovery indicates a reduced responsiveness of the glomerular vasculature to TxA2, and explored whether changes in TxA2 receptor protein expression and receptor-ligand binding are underlying mechanisms.. Glomerulonephritis was induced in male Sprague-Dawley rats using an antibody raised in rabbits against rat particulate glomerular basement membrane (GBM). Changes in Tx receptor levels were assessed in protein lysates of glomeruli on days 3 and 7 after a single intravenous injection of the anti-GBM antibody. Ligand-binding studies were performed at the same time points using isolated glomeruli and the TxA2 receptor ligand [3H]-SQ-29,548. GFR was measured as the clearance of endogenous creatinine.. There was a marked increase in Tx receptor protein in the lysates of nephritic glomeruli on days 3 and 7. In contrast, binding sites (Bmax) of [3H]-SQ-29,548 decreased, indicating that the excess receptor became either inaccessible to its ligand (sequestered) or desensitized. Daily administration of the Tx synthase inhibitor Furegrelate starting prior to injection of anti-GBM antibody prevented the decrease in [3H]-SQ-29,548 binding. Furegrelate treatment starting in an established stage of nephritis had no effect. In these animals, GFR was lower than nephritic controls not treated with Furegrelate.. These observations indicate that in the course of glomerulonephritis, there is a marked increase in glomerular Tx receptor expression. The enhanced intraglomerular TxA2 synthesis causes either a sequestration or desensitization of its receptor. As a result, access of unbound TxA2 to efferent arterioles may become facilitated, and constriction of these arterioles may preserve GFR.

Topics: Animals; Benzofurans; Disease Models, Animal; Enzyme Inhibitors; Glomerular Filtration Rate; Glomerulonephritis; Kidney Glomerulus; Kinetics; Ligands; Male; Rabbits; Rats; Rats, Sprague-Dawley; Receptors, Thromboxane; Thromboxane A2; Thromboxane-A Synthase

IUGR was induced by maternal administration of synthetic thromboxane A2 (STA2) from the 13th day of gestation. Fetuses and neonates showed a markedly significant weight reduction. In E16 IUGR brain, no pathological abnormalities were found, but morphological changes appeared in the cortical plate of E18 IUGR brain. In E20 IUGR brain, ectopic clusters of differentiating cells cytologically mimicking neuroblasts were found in the neuroepithelial layer, but these abnormal clusters of cells in IUGR brain of late gestation were never observed in PN7. Morphometric analysis of coronal-sectional areas of the brain and cortical plate demonstrated that there were no differences between IUGR rats and controls in E16 and E18. These areas were, however, significantly reduced in E20 and PN7 growth-retarded rats compared with the control. Because the period of STA2 administration coincides with the neuro-developmental stage of cell migration and differentiation, reduction of the uteroplacental blood supply might cause a transient abnormal cytoarchitecture of the cerebral cortex resulting in brain growth retardation.

Topics: Animals; Animals, Newborn; Body Weight; Brain; Brain Diseases; Disease Models, Animal; Embryonic and Fetal Development; Female; Fetal Growth Retardation; Pregnancy; Rats; Rats, Sprague-Dawley; Thromboxane A2

We have previously shown that in the rat a diet high in cholesterol and deficient in vitamin E and selenium results in hypercholesterolaemia and increased lipid oxidation. We utilized this model to determine whether rats given this diet develop impaired endothelium-dependent relaxation mediated by nitric oxide (NO) in mesenteric and in renal vessels. In addition, we tested whether the impairment is due to (i) decreased endothelial NO synthase activity, (ii) increased NO inactivation and/or (iii) increased production of the endothelium-derived constricting factors thromboxane A2/prostaglandin H2 and endothelin-1. We also investigated whether endothelial dysfunction induced by dyslipidaemia increases the sensitivity for the development of hypertension in response to high dietary salt.. Male Dahl salt-sensitive (DSS) rats were divided into three groups and received a standard diet (control group), a high (4%) cholesterol diet (HChol), or a high cholesterol diet deficient in the anti-oxidants vitamin E and selenium (HChol-Def). The NaCl content of these diets was 0.5%. After 18 weeks we studied endothelium-dependent relaxation in response to acetylcholine (ACh) in aortas and in isolated perfused preparations of mesenteric arteries and kidneys. In some experiments, ifetroban, a thromboxane A2/prostaglandin H2 receptor antagonist, was added to the organ bath or the perfusion buffer. Vascular responses to endothelin-1 as well as to BQ-123, an endothelin A receptor blocker, were studied in the isolated perfused kidneys. In addition, two extra groups of rats were fed a diet high in sodium chloride (2%): one of the groups received the normal cholesterol diet whereas the other group received the diet high in cholesterol and deficient in vitamin E and selenium.. Compared to normocholesterolemic rats, responses to ACh were significantly impaired in aortas, mesenteric arteries and kidneys of HChol-Def rats (P < 0.01). Endothelial NO synthase activity (conversion of [14C]L-arginine to [14C]L-citrulline) was similar in aortas of control, HChol and HChol-Def rats; thus suggesting that impaired endothelium-dependent relaxation in the HChol-Def rats was not due to decreased cNOS catalytic activity. Ifetroban improved the impaired endothelium-dependent relaxation in mesenteric vessels, but not in aortas and kidneys. Endothelin-1 (ET-1: 10(-13)-10(-11) mol/l) elicited NO-mediated relaxations in kidneys of control rats but not in kidneys of HChol-Def; blockade of ET-1 with BQ-123, an ET(A) receptor blocker, did not improve NO-mediated relaxation of HChol-Def. Despite impaired endothelium-dependent relaxation in renal and mesenteric vessels, HChol-Def DSS rats failed to develop hypertension (systolic blood pressure 144 +/- 1 in control and 150 +/- 2 mmHg in HChol-Def) but manifested a significant increase in sensitivity to the pressor effects of a high (2% NaCl) dietary salt content during the initial 10 weeks of the study, although the final blood pressure at 18 weeks was similar in both groups.. These studies support the notion that (i) products of lipid oxidation may reduce NO bioactivity without affecting endothelial NO synthase mass or catalytic activity, (ii) the mechanisms involved in the endothelial dysfunction induced by hypercholesterolaemia and oxidized lipids may differ among vascular beds, and (iii) decreased NO bioavailability does not necessarily result in systemic hypertension, but it may enhance the sensitivity to the hypertensinogenic effect of dietary salt.

Topics: Acetylcholine; Animals; Aorta; Blood Pressure; Body Weight; Diet; Disease Models, Animal; Endothelin-1; Endothelins; Endothelium, Vascular; Hypercholesterolemia; Hypertension; Kidney; Male; Mesenteric Arteries; Nitric Oxide; Nitric Oxide Synthase; Perfusion; Prostaglandin H2; Prostaglandins H; Rats; Thromboxane A2

The role of cysteinyl leukotrienes (cys-LTs) and thromboxane A(2) (TXA(2)) in guinea pig models of aspects of bronchial asthma was investigated. In a novel antigen (BSA)-induced asthmatic model using passively sensitized guinea pigs, pretreatment with varying doses of indomethacin controlled the ratio of followed lipid mediators, LTC(4)/D(4)/E(4) and TXB(2), in lungs of challenged guinea pigs. The predominant mediator in indomethacin-untreated asthma was TXA(2), and complete inhibition of cyclooxygenase by i.v. injection of 5-mg/kg indomethacin-induced cys-LTs mainly mediated asthmatic response. Furthermore, a 1-mg/kg indomethacin dose induced an asthmatic state where both cys-LTs and TXA(2) equally participated. Either LTD(4) or TXA(2) receptor antagonists given alone inhibited the asthmatic response in conditions where the corresponding mediator plays a predominant role. The combination of LTD(4) and TXA(2) receptor antagonists exhibited significant effects irrespective of the condition used. Under conditions where both mediators equally participate, a combination of both receptor antagonists showed additive inhibition. YM158, a newly synthesized and orally active dual antagonist for LTD(4) and TXA(2) receptors, showed the same antiasthmatic effect as a combinated LTD(4) receptor antagonist and a TXA(2) receptor antagonist mixture. Therefore, broad-acting compounds such as YM158 are expected to have antiasthmatic efficacies in a broader class of asthmatic patients than single-acting drugs.

Topics: Administration, Oral; Animals; Asthma; Chromones; Disease Models, Animal; Guinea Pigs; Immunization, Passive; Leukotriene Antagonists; Leukotrienes; Male; Membrane Proteins; Phenylacetates; Receptors, Leukotriene; Receptors, Thromboxane; Serum Albumin, Bovine; Sulfonamides; Tetrazoles; Thiazoles; Thromboxane A2; Thromboxane B2

To evaluate the hemodynamic effects of inhaled nitric oxide (NO) during a venous air infusion (VAI) in dogs. We also addressed the question of whether NO therapy changes thromboxane (Tx) A(2) release and nitrate/nitrite production during a VAI.. Prospective trial.. University laboratory.. Anesthetized mongrel dogs received a VAI (0.2 ml x kg(-1)x min(-1)) after the measurement of baseline hemodynamics. Control dogs (n = 8) received no further treatment. After 30 min of VAI, NO 3 ppm inhalation was initiated (n = 7) for 30 min, followed by 30 min without NO inhalation, and then a final 30 min of NO 40 ppm treatment. Hemodynamic variables were registered and arterial and mixed venous blood samples were drawn for gas analysis and for the determinations of serum TxB(2) (by enzyme-linked immunosorbent assay) and nitrate/nitrite (by high-performance liquid chromatography) levels.. The cardiac index increased 24 % and the pulmonary vascular resistance index decreased 30 % during both periods of NO inhalation. Arterial oxygen tension and arterial oxygen saturation were slightly lower after NO therapy. Nitrate/nitrite concentrations were unaltered in the control group and there were no differences between the arterial and mixed venous serum nitrate/nitrite levels. Nitrite concentrations remained below 1 microM in both groups of animals, but the nitrate concentration increased after inhalation of 40 ppm NO. Serum TxB(2) increased after 60 min of VAI in the control group, but there was no increase in NO-treated animals (all p < 0.05). Nitrate/nitrite concentrations were unaltered after VAI in dogs. NO therapy attenuated TxA(2) release and improved hemodynamics, but not blood oxygenation, in dogs with a VAI. There were no differences between the responses to 3 ppm and 40 ppm NO.

Topics: Administration, Inhalation; Animals; Disease Models, Animal; Dogs; Drug Evaluation, Preclinical; Embolism, Air; Female; Hemodynamics; Hypertension, Pulmonary; Male; Nitrates; Nitric Oxide; Nitrites; Prospective Studies; Thromboxane A2; Thromboxane B2; Vasodilator Agents; Veins

In glomerulonephritis there is co-activation of the arachidonic acid cyclooxygenase pathway toward synthesis of prostaglandins (PG) and thromboxane (Tx) and of lipoxypenase pathways toward synthesis of hydroxyeicosatetraenoic acids (HETEs) and leukotrienes (LTs). Cyclooxygenase inhibition with non-steroidal anti-inflammatory drugs results in enhanced glomerular LT synthesis with potentially adverse effects on the severity of the inflammation. The effect of Tx inhibition or antagonism on LT synthesis is unknown. Because TxA2 is the most abundant eicosanoid synthesized in nephritic glomeruli, and because TxA2 synthase inhibitors and receptor antagonists are now available for the treatment of glomerulonephritis, it becomes important to address this question. In this study we assessed the effect of a TxA2 synthase inhibitor, Dazmegrel, and a TxA2 receptor antagonist, SQ-29 548, on glomerular PGE2, LTB4, and 12-HETE synthesis in a model of mesangial nephritis induced in the rat by the administration of a monoclonal antibody against the Thy 1.1 antigen of rat mesangial cells. Dazmegrel, in doses sufficient to effectively block glomerular TxA2 synthesis, significantly increased 12-HETE and PGE2 synthesis without an effect on the synthesis of LTB4. SQ-29 548 had no effect on glomerular PGE2, LTB4, or 12-HETE production. Because PGE2 preserves kidney function in glomerulonephritis, and because 12-HETE inhibits 5-lipoxygenase, the enhanced PGE2 and 12-HETE production within nephritic glomeruli after TxA2 synthase inhibition may be a superior anti-inflammatory strategy when compared with TxA2 receptor antagonism.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Animals; Antilymphocyte Serum; Bridged Bicyclo Compounds, Heterocyclic; Dinoprostone; Disease Models, Animal; Fatty Acids, Unsaturated; Glomerulonephritis, Membranoproliferative; Hydrazines; Kidney Glomerulus; Leukotriene B4; Macrophages; Rats; Rats, Wistar; Thromboxane A2; Thromboxane-A Synthase; Thy-1 Antigens

Platelet aggregation at sites of vascular injury releases both peptide growth factors and vasoactive compounds. Although significant attention has been focused on peptide growth factors, very little is known about the mitogenic effect of vasoactive compounds. We evaluated the effect of serotonin (5-HT) and thromboxane A2 (TXA2) mimetic U46619 alone and in combination on aortic endothelial cells. Stimulation of endothelial cells by 5-HT resulted in an increase in tritiated thymidine uptake and an increase in cell number, whereas U46619 did not have any significant effect. However, when endothelial cells were exposed to both compounds, U46619 potentiated the mitogenic effect of 5-HT on endothelial cells. When endothelial cells were preincubated with LY281067 (a 5-HT2 receptor antagonist) or ridogrel (a combined TXA2 synthase inhibitor and receptor antagonist), LY281067 blocked the mitogenic effect of 5-HT and ridogrel blocked the potentiating effect of U46619 on 5-HT2-induced tritiated thymidine incorporation. When endothelial cells were preincubated with both antagonists, the effects of both 5-HT and U46619 were blocked. Recent studies have indicated that regenerating endothelial cells at sites of vascular injury may release growth factors for vascular smooth muscle cells, leading to smooth muscle cell proliferation and development of neointima. This study suggests that the combined use of 5-HT and TXA2 receptor antagonists may inhibit the growth of endothelial cells at sites of vascular injury and attenuate the formation of neointima.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Cell Division; Cells, Cultured; Disease Models, Animal; Endothelium, Vascular; Lysergic Acid; Male; Muscle, Smooth, Vascular; Pentanoic Acids; Platelet Aggregation; Pyridines; Rabbits; Serotonin; Serotonin Antagonists; Thromboxane A2; Thromboxane-A Synthase; Thymidine; Vasoconstrictor Agents

It is well known that lung embolism is associated with an increase in pulmonary vascular resistance. Since the mechanisms of pulmonary vascular reactions during embolism are still unclear, the aim of this study was to investigate the potential involvement of endothelin-1 (ET-1) and thromboxane A2 (TXA2) as mediators of the pulmonary artery pressure (PAP) increase after embolism using the selective ETA receptor antagonist LU135252 [1], the ETB receptor antagonist BQ788 [2], and the cyclooxygenase inhibitor diclofenac.. Prospective experimental study in rabbits.. Experimental laboratory in a university teaching hospital.. 36 adult rabbits of either sex.. The experiments were performed in 36 isolated and ventilated rabbit lungs which were perfused with a buffer solution containing 10% of autologous blood. Embolism was induced by the injection of 0.75 ml air into the pulmonary artery.. PAP and lung weight, reflecting edema formation, were continuously recorded. Perfusate samples were drawn intermittently to determine TXA2 and ET-1 concentrations. Air injection resulted in an immediate increase in PAP up to 22.8 +/- 1.4 mm Hg at 2.5 min (control, n = 6), which was parallelled by an enhanced generation of TXA2. No relevant edema formation occurred during the observation period. Pretreatment with the ETA receptor antagonist LU135252 significantly reduced the pressure reaction after air embolism (p < 0.001) whereas the ETB receptor antagonist BQ788 (n = 6) was without marked effects. The administration of diclofenac (n = 6) did not alter the PAP increase 2.5 min after embolism, but significantly reduced the pressure reaction during the further observation period (p < 0.001). The application of LU135252 and diclofenac together (n = 6) also significantly reduced the PAP increase from 2.5 min during the total observation period (p < 0.001).. The acute pressure reaction after air embolism is mainly mediated via ET-1 by an ETA receptor related mechanism. TXA2 seems to maintain this reaction for a longer time.

Topics: Analysis of Variance; Animals; Cyclooxygenase Inhibitors; Diclofenac; Disease Models, Animal; Embolism, Air; Endothelin Receptor Antagonists; Endothelin-1; Enzyme-Linked Immunosorbent Assay; Hypertension, Pulmonary; In Vitro Techniques; Oligopeptides; Perfusion; Phenylpropionates; Piperidines; Pulmonary Artery; Pulmonary Embolism; Pyrimidines; Rabbits; Radioimmunoassay; Thromboxane A2; Time Factors; Vascular Resistance

To elucidate the role of thromboxane A2 (TxA2) and prostaglandin I2 (PGI2) in acute necrotizing pancreatitis (ANP) in rats and to determine the effect of the TxA2 synthesis inhibitor OKY-046 and the PGI2 analogue OP-2507, the levels of two prostanoids (TxB2, 6-keto PGF1alpha) and two types of phospholipase A2 (PLA2) activity (cytosolic and secretory) were measured in plasma and three tissues (pancreas, lung, and kidney) after injection of a mixed solution of 5% sodium taurocholate and 0.1% trypsin into the pancreatic duct to induce ANP. The survival rate 24 h after inducing ANP was 33.3% in the nontreated group, versus 83.3 and 58.3% in the groups treated with OKY-046 and OP-2507, respectively. Only the group treated with OKY-046 showed significant improvement compared with the nontreated group. The plasma, pancreatic, and pulmonary TxB2 levels decreased significantly in the group treated with OKY-046, and the histopathological changes were not as severe. The levels of pancreatic and pulmonary cytosolic PLA2 activities decreased, and plasma and pancreatic secretory PLA2 activities also decreased. In conclusion, the levels of both types of PLA2 activity and TxA2 production decreased, and the survival rate improved as a result in the group treated with OKY-046, but OP-2507 had no effect on ANP. TxA2 and two types of PLA2 activity play an important role in the process of aggravation of acute pancreatitis.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Disease Models, Animal; Epoprostenol; Injections, Subcutaneous; Kidney; Lung; Male; Methacrylates; Pancreas; Pancreatitis, Acute Necrotizing; Phospholipases A; Phospholipases A2; Rats; Rats, Wistar; Survival Rate; Taurocholic Acid; Thromboxane A2; Thromboxane B2; Thromboxane-A Synthase; Time Factors

Susceptibility to drug-induced coronary vasospasm in rhesus monkeys increases after removal of the ovaries and can be normalized by adding back physiological levels of estradiol-17ss (E2) and/or natural progesterone (P) in vivo as reported recently by our group. Furthermore, the reactivity status (Ca2+ and protein kinase C responses) of freshly isolated and primary culture coronary artery vascular muscle cells (VMC) mimic the intact coronary artery responses to 5-HT + U46619. Since coronary reactivity is maintained in the isolated VMC, we hypothesized that the reactivity state inherent in the VMC was modulated directly by ovarian steroids in vitro as in the whole animal. To test this hypothesis, we treated hyperreactive VMC from ovariectomized (ovx) monkeys in vitro with E2 or P and measured VMC reactivity to combined stimulation with 5-HT and U46619, as determined by the amplitude and especially the duration of intracellular Ca2+ signals, as well as protein kinase C (PKC) activation/translocation. VMC were treated for 12 96 h with 3 100 pg/ml E2 (10 365 pM) and/or 0.3 3 ng/ml P (0.95 9.5 nM). Hyperreactive responses to the combination of 5-HT and U46619 in untreated VMC were significantly and dose-dependently reduced by treatment in vitro with physiological levels of either E2 or P for at least 24 h. Both the early transient and late sustained increases in intracellular Ca2+ and PKC translocation were blunted, and the effects of 0.2 nM E2 and 3.2 nM P were specifically antagonized by the receptor blockers ICI 182,780 (200 nM) and RU486 (15 nM), respectively. Antibodies to the estrogen receptor and progesterone receptor labeled nuclei in VMC, which were also positively labeled by a smooth muscle myosin heavy chain monoclonal antibody. These data indicate that natural ovarian steroids directly reduce hyperreactive 5-HT and thromboxane A2-stimulated Ca2+ and PKC responses of coronary artery VMC from surgically menopausal rhesus macaques. We hypothesize that vascular hyperreactivity, which may be a critical factor involved in the increased incidence of coronary artery vasospasm and ischemic heart disease in postmenopausal women, can be normalized by E2 and/or P through direct actions on coronary artery vascular muscle cells.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Calcium Signaling; Coronary Vasospasm; Coronary Vessels; Disease Models, Animal; Disease Susceptibility; Enzyme Activation; Estradiol; Estrogen Antagonists; Female; Fulvestrant; Hormone Antagonists; Hormone Replacement Therapy; Humans; Macaca mulatta; Microscopy, Confocal; Microscopy, Fluorescence; Mifepristone; Muscle Proteins; Muscle, Smooth, Vascular; Ovariectomy; Postmenopause; Progesterone; Protein Kinase C; Receptors, Estrogen; Receptors, Progesterone; Serotonin; Thromboxane A2; Vasoconstriction

To examine the pathophysiologic role of vasoactive eicosanoids and endothelin-1 in granulocyte-mediated effects in the pulmonary vasculature.. Prospective experimental study in rabbits.. Experimental laboratory in a university teaching hospital.. Thirty adult rabbits.. The experiments were performed on 30 isolated and ventilated rabbit lungs that were perfused with a cell- and plasma-free buffer solution.. The pulmonary arterial pressure and the lung weight gain were continuously registered. Intermittently perfused samples were taken to determine endothelin-1 and thromboxane A2 concentrations. Six experiments without intervention served as the sham group. The granulocytes in the pulmonary circulation were stimulated with N-formyl-L-leucin-methionyl-L-phenylalanine (FMLP; 10(-6) M; control, n = 6). To investigate whether activated granulocytes influence the pulmonary vasculature via endothelin-1, the endothelin-A receptor antagonist LU135252 (10(-6) M) was added to the perfusate before FMLP injection (n = 6). The potential involvement of thromboxane A2 in granulocyte-endothelial interaction was investigated by pretreatment with the cyclooxygenase inhibitor diclofenac (10 microg/mL; n = 6). Activation of granulocytes resulted in an acute increase in pulmonary arterial pressure (>9 mm Hg), which was followed by a second delayed pressure increase after 60 mins (>14 mm Hg) and was paralleled by a massive generation of thromboxane A2 (>250 pg/ mL). Fifteen minutes after FMLP-injection, endothelin-1 was detectable in the perfusate. Pretreatment with the selective endothelin-A antagonist LU135252 significantly (p< .01) reduced the initial pressure response after FMLP stimulation, while diclofenac significantly reduced (p < .05) the delayed pressure increase. Using diclofenac (10 microg/mL) in conjunction with LU135252 (10(-6) M; n = 6) before FMLP injection significantly reduced the early and the delayed pressure increase.. Activated granulocytes seem to enhance pulmonary vascular resistance via endothelin-1 and thromboxane A2. The endothelin-1 effects are probably mediated via endothelin-A receptors since the endothelin-A receptor antagonist LU135252 was able to suppress the early pressure reaction after FMLP injection, whereas the cyclooxygenase inhibitor diclofenac was able to reduce the second pressure increase.

Topics: 6-Ketoprostaglandin F1 alpha; Analysis of Variance; Animals; Cyclooxygenase Inhibitors; Diclofenac; Disease Models, Animal; Endothelin Receptor Antagonists; Endothelin-1; Female; Granulocytes; In Vitro Techniques; Male; N-Formylmethionine Leucyl-Phenylalanine; Perfusion; Phenylpropionates; Prospective Studies; Pulmonary Artery; Pyrimidines; Rabbits; Random Allocation; Respiratory Distress Syndrome; Thromboxane A2; Thromboxane B2; Vascular Resistance

Severe perinatal aspiration of meconium is frequently complicated by unsuccessful neonatal adaptation with associated pulmonary hypertension. This vascular complication is supposedly related to pulmonary release of vasoconstrictory agents, including metabolites of arachidonic acid. Thus, to investigate the role of prostanoids on these meconium-induced circulatory changes in the lungs, the hemodynamic response to meconium instillation was studied in acetylsalicylic acid-pretreated juvenile pigs. Twelve 10-wk-old pigs with adapted lung circulation received 3 mL/kg of 65 mg/mL human meconium via the endotracheal tube. Six of them were medicated with 10 mg/kg acetylsalicylic acid 30 min before meconium insufflation. Hemodynamic parameters and urinary excretion of stable metabolites of thromboxane A2 and prostacyclin were measured serially for 6 h after the insult. Meconium administration induced a biphasic increase in mean pulmonary artery pressure and pulmonary vascular resistance, and a rapid rise in urinary levels of prostanoid metabolites. Acetylsalicylic acid pretreatment prevented the initial (0-1 h) pulmonary hypertensive response and increase in prostanoid excretion. During the second phase (1-6 h), acetylsalicylic acid did not attenuate the progressive increase in mean pulmonary artery pressure and pulmonary vascular resistance nor did it affect the longitudinal distribution of the pulmonary resistances. Our results thus show that in adapted porcine lungs, arachidonic acid metabolites contribute to the early hypertensive response, but have only minor effects during the second phase vascular hypertension.

Topics: Adaptation, Physiological; Animals; Animals, Newborn; Aspirin; Cyclooxygenase Inhibitors; Disease Models, Animal; Epoprostenol; Humans; Infant, Newborn; Meconium Aspiration Syndrome; Persistent Fetal Circulation Syndrome; Swine; Thromboxane A2; Time Factors

Acute lung injury is associated with pulmonary hypertension, intrapulmonary shunting, and increased microvascular permeability, leading to altered oxygenation capacity. Thromboxane A2 has been found to be a central mediator in the development of septic and oleic acid (OA)-induced acute lung injury. Our previous study demonstrated a beneficial effect of preinjury thromboxane A2 receptor blockade. The current study examines the efficacy of postinjury receptor blockade on oxygenation capacity and pulmonary hemodynamics in an isolated lung model of OA-induced acute lung injury.. Four groups of rabbit heart-lung preparations were studied for 60 minutes in an ex vivo perfusion-ventilation system. Saline control lungs received saline solution during the first 20 minutes of study. Injury control lungs received an OA-ethanol solution during the first 20 minutes. Two treatment groups were used: T10, in which the thromboxane receptor antagonist, SQ30741, was infused 10 minutes after the initiation of OA infusion; and T30, in which the thromboxane receptor antagonist was infused 30 minutes after OA infusion.. Significant differences were found in oxygenation (oxygen tension in T10 = 62.6 +/- 11.7 mm Hg, T30 = 68.2 +/- 21.2 mm Hg; injury control = 40.2 +/- 9.0 mm Hg, saline control = 123.5 +/- 16.01 mm Hg; p < 0.001) and percentile change in pulmonary artery pressure (T10 = 1.1% +/- 19.4% increase, T30 = 11.2% +/- 7.3% increase; injury control = 47.6% +/- 20.5%, saline control = 4.2% +/- 6.81%; p < 0.001).. This study demonstrates that blockade of the thromboxane A2 receptor, even after the initiation of acute lung injury, eliminates pulmonary hypertension and improves oxygenation.

Topics: Animals; Bacterial Infections; Blood Pressure; Capillary Permeability; Disease Models, Animal; Ethanol; Fibrinolytic Agents; Hypertension, Pulmonary; Infusions, Intravenous; Microcirculation; Oleic Acid; Oxygen; Pulmonary Artery; Pulmonary Circulation; Rabbits; Receptors, Thromboxane; Respiratory Distress Syndrome; Thromboxane A2; Tidal Volume; Time Factors; Ventilation-Perfusion Ratio

Ultrasonically nebulized distilled water-induced bronchoconstriction (UNDW-IB) is specific to asthma. The mechanisms underlying UNDW-IB are not fully understood, and no reproducible animal model has been reported. The purpose of this study was to develop a guinea-pig model of UNDW-IB. Ultrasonically nebulized distilled water (UNDW) was inhaled 20 min after an aerosolized antigen challenge in passively sensitized and artificially ventilated guinea-pigs. UNDW was also inhaled 5 and 20 min after 0.1 mg x mL(-1) methacholine inhalation in nonsensitized animals. In addition, 0.1 mg x kg(-1) S-1452, a thromboxane A2 antagonist, or saline was given intravenously 5 min before UNDW inhalation in sensitized animals. The inhalation of UNDW caused bronchoconstriction, when inhaled 20 min after an antigen challenge in sensitized guinea-pigs. UNDW inhalation did not produce bronchoconstriction after saline inhalation in nonsensitized or sensitized guinea-pigs, or after antigen inhalation in nonsensitized animals. Methacholine-induced bronchoconstriction did not evoke UNDW-IB. Neither did S-1452 reduce the UNDW-IB. In conclusion, the guinea-pig model of ultrasonically nebulized distilled water-induced bronchoconstriction developed in this study suggests that allergic reaction, but not bronchoconstriction, can induce bronchial hyperresponsiveness to ultrasonically nebulized distilled water, and that thromboxane A2 is not involved in ultrasonically nebulized distilled water-induced bronchoconstriction.

Topics: Administration, Inhalation; Albuterol; Animals; Asthma; Bronchial Hyperreactivity; Bronchial Provocation Tests; Bronchoconstriction; Bronchodilator Agents; Disease Models, Animal; Guinea Pigs; Male; Nebulizers and Vaporizers; Reference Values; Thromboxane A2; Water

Our study was designed to investigate whether angiotensin II subtype 1 (AT1) receptors are involved in the constrictor responses evoked by endothelin-1 and the thromboxane A2 analogue U46619 in aortic rings from spontaneously hypertensive rats (SHR), by studying the effect of the AT1 receptor antagonist losartan. In addition, since nitric oxide seems to participate in the mechanism of action of losartan, we studied the effect of the nitric oxide synthesis inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), on the action of losartan.. Dose-response curves of either endothelin-1 (10(-10) to 10(-7) mol/l) or U46619 (10(-10) to 10(-6) mol/l) were studied in the presence or absence of losartan (10(-5) mol/l) in aortic rings from SHR. Likewise, similar experiments were done in aortic rings pretreated with the nitric oxide synthesis inhibitor, L-NAME (10(-4) mol/l).. Pre-incubation with losartan significantly reduced the contractile response to endothelin-1 compared with control rings, without modifying the value represented by 50% of the maximal response (pD2). The concentration-response curve to U46619 was shifted to the right in the presence of losartan, reducing the pD2 compared with control rings. The presence of captopril (10(-5) mol/l) in the incubation media did not alter the response to either endothelin-1 or U46619. The diminished response to both endothelin-1 and U46619 in the presence of losartan was reversed in L-NAME-pretreated rings.. Angiotensin II seems to participate in the vasoconstriction induced by both endothelin-1 and the thromboxane A2 analogue through the stimulation of AT1 receptors in SHR aortic rings, because losartan inhibited this effect. Moreover, nitric oxide appears to be involved in this action of losartan.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Antihypertensive Agents; Aorta, Thoracic; Disease Models, Animal; Dose-Response Relationship, Drug; Endothelin-1; Enzyme Inhibitors; Hypertension; Losartan; Male; NG-Nitroarginine Methyl Ester; Nitric Oxide; Rats; Rats, Inbred SHR; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Receptors, Angiotensin; Thromboxane A2; Vasoconstriction; Vasoconstrictor Agents

Monocrotaline (MCT)-induced pulmonary hypertension (PH) is a useful model for the investigation of this disorder in humans. The role of thrombocytes in the genesis of PH has already been addressed; however, the exact mechanism by which they induce PH remains to be elucidated. We investigated the effects of a thromboxane A2 (TXA2) synthase inhibitor (OKY-046) and a TXA2/prostaglandin H2 (PGH2) receptor antagonist (ONO-8809) on the development of MCT-induced PH. A single dose of MCT (60 mg/kg bodyweight; BW) was injected subcutaneously in Wistar rats 24 h after the administration of OKY-046 or ONO-8809. The TXA2 inhibitors were administered by gavage daily for 3 weeks. Urinary excretion of eicosanoids was determined by radioimmunoassay. At the end of the treatment period, the lungs, heart and kidneys were morphologically examined. The per cent medial thickness of the muscular pulmonary arteries (%MT) and the ratio of the right to the left ventricular mass including the septum (RV/LV + S) increased significantly in MCT-treated rats compared with the control rats. The %MT was attenuated by the administration of ONO-8809. Either OKY-046 or ONO-8809 attenuated the increase in RV/LV + S. In addition, both TXA2 inhibitors reduced urinary excretion of 11-dehydro-TXB2, particularly during the early phase of PH, suggesting that platelet aggregation was reduced. These findings suggest that the inhibition of TXA2 by synthase inhibition or receptor antagonism reduces or delays the development of MCT-induced PH in rats, probably by inhibiting platelet aggregation.

Topics: Animals; Bridged Bicyclo Compounds; Disease Models, Animal; Eicosanoids; Fatty Acids, Monounsaturated; Hypertension, Pulmonary; Male; Methacrylates; Monocrotaline; Prostaglandin Antagonists; Rats; Rats, Wistar; Reference Values; Thromboxane A2; Thromboxane-A Synthase

To test the hypothesis that pulmonary vasodilator responses to pentoxifylline are dependent on the synthesis of nitric oxide from L-arginine and are independent of the release of cyclooxygenase products.. Prospective study.. Research laboratory.. Isolated lobar lung preparation, using mongrel cats.. In separate experiments, the effects of NG-L-nitro-L-arginine methyl ester, an inhibitor of nitric oxide synthase, and the effects of a cyclooxygenase blocker, meclofenamate, were investigated on pulmonary arterial responses to pentoxifylline, acetylcholine, and isoproterenol during increased tone conditions induced by the thromboxane A2 mimic, U46619, in the pulmonary vascular bed of the cat.. Lobar arterial perfusion pressure, systemic pressure, and left atrial pressure were continuously monitored, electronically averaged, and permanently recorded. Under increased tone conditions in the isolated left lower lobe vascular bed of the cat, NG-L-nitro-L-arginine methyl ester significantly reduced the vasodilator responses to pentoxifylline and to acetylcholine, whereas NG-L-nitro-L-arginine methyl ester had no significant effect on the vasodilator responses to isoproterenol. Vasodilator responses to pentoxifylline and acetylcholine were not significantly changed in the presence of meclofenamate, whereas meclofenamate markedly reduced the vasopressor effects of arachidonic acid.. These data show that pentoxifylline has significant vasodilator activity in the pulmonary vascular bed of the cat. The present data also suggest that responses to pentoxifylline during increased tone conditions may, in part, be mediated by the release of nitric oxide and are independent of the release of cyclooxygenase products.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Acetylcholine; Animals; Arginine; Bronchodilator Agents; Cats; Cyclooxygenase Inhibitors; Disease Models, Animal; Drug Evaluation, Preclinical; Drug Interactions; Isoproterenol; Meclofenamic Acid; NG-Nitroarginine Methyl Ester; Nitric Oxide; Pentoxifylline; Prostaglandin Endoperoxides, Synthetic; Pulmonary Circulation; Thromboxane A2; Vasodilator Agents

Adult respiratory distress syndrome remains a major cause of morbidity and mortality. We investigated the role of thromboxane receptor antagonism in an experimental model of acute lung injury that mimics adult respiratory distress syndrome.. Three groups of rabbit heart-lung preparations were studied for 30 minutes in an ex vivo blood perfusion/ventilation system. Saline control (SC) lungs received saline solution during the first 20 minutes of study. Injury control (IC) lungs received an oleic acid-ethanol solution during the first 20 minutes. Thromboxane receptor blockade (TRB) lungs received the same injury as IC lungs, but a thromboxane receptor antagonist (SQ30741) was added to the blood perfusate just prior to study. Blood gases were obtained at 10-minute intervals, and tidal volume, pulmonary artery pressure, and lung weight were continuously recorded. Oxygenation was assessed by measuring the percent change in oxygen tension over the 30-minute study period. Tissue samples were collected from all lungs for histologic evaluation.. Significant differences were found between SC and IC lungs as well as TRB and IC lungs when comparing pulmonary artery pressure (SC = 33.1 +/- 2.2 mm Hg, TRB = 35.4 +/- 2.1 mm Hg, IC = 60.4 +/- 11.1 mm Hg; p < 0.02) and percent change in oxygenation (SC = -20.6% +/- 10.3%, TRB = -24.2% +/- 9.5%, IC = -57.1% +/- 6.2%; p < 0.03). None of the other variables demonstrated significant differences.. Thromboxane receptor blockade prevents the pulmonary hypertension and the decline in oxygenation seen in an experimental model of acute lung injury that mimics adult respiratory distress syndrome.

Topics: Animals; Blood Gas Analysis; Disease Models, Animal; Hypertension, Pulmonary; Lung; Oxygen; Rabbits; Receptors, Thromboxane; Respiratory Distress Syndrome; Thromboxane A2

An experimental model of acute thrombosis was developed in pentobarbital- anesthetized ferrets. A 10-min anodal electrical stimulation of 1 mA was delivered to the external surface of the carotid artery while measuring carotid blood flow (CBF). This produced an occlusive thrombus in all vehicle-treated ferrets within 41 +/- 3 min with an average weight of 8 +/- 1 mg (n = 7). These thrombi were enriched in both platelets and fibrin and were adherent at the site of transmural vascular injury as determined by light and electron microscopy. To determine the model's sensitivity to antiplatelet drugs, aspirin or a thromboxane (TxA2) receptor antagonist (ifetroban) were administered 15 min before electrical stimulation. Thrombus weight was reduced 58% by aspirin (10 mg/kg, i.v.) and 74% by ifetroban (1 mg/kg + 1 mg/kg per hr, i.v.). Both drugs also improved CBF and decreased vascular occlusion. Ferrets were more sensitive than rats to aspirin's inhibition of collagen-induced platelet aggregation as determined ex vivo in whole blood. Separate in vitro platelet aggregation studies revealed species differences in reactivity to U-46619 (TxA2 receptor agonist) and collagen in the order of human > ferret > rat, with relatively lesser variations in ADP responses. These studies identify the ferret as a useful species for evaluating antithrombotic drugs in a model in which aspirin is efficacious.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Aspirin; Blood Platelets; Bridged Bicyclo Compounds, Heterocyclic; Carotid Arteries; Carotid Artery Injuries; Collagen; Disease Models, Animal; Electric Stimulation; Ferrets; Fibrin; Humans; In Vitro Techniques; Male; Microscopy, Electron; Microscopy, Electron, Scanning; Oxazoles; Platelet Aggregation; Platelet Aggregation Inhibitors; Prostaglandin Endoperoxides, Synthetic; Prothrombin Time; Rats; Rats, Sprague-Dawley; Regional Blood Flow; Species Specificity; Thrombosis; Thromboxane A2; Vasoconstrictor Agents

Whether the alterations in the synthesis of thromboxane A2 (TXA2) is the direct mechanism underlying the blood pressure-lowering effect of fish oil was investigated in this study. Six groups of 11 male spontaneously hypertensive rats were fed semipurified diets containing corn or fish oils and graded levels (50, 5000 or 15,000 ppm) of dietary vitamin E for 8 weeks. Plasma TXA2, assayed by RIA, was significantly greater in the corn oil group than in the fish oil group (P < 0.05). Compared to 50 ppm dietary vitamin E, 5000 and 15 000 ppm dietary vitamin E, respectively, significantly decreased plasma TXA2 (P < 0.05). Systolic, mean or diastolic blood pressure, evaluated by the tail cuff method, were significantly higher in the corn oil group than in the fish oil group (P < 0.05). However, vitamin E had no effect on blood pressure. No relationship between TXA2 and blood pressure was found. Experimental results indicated that the alterations in the synthesis of TXA2 were not the direct antihypertensive effect of fish oil.

Topics: Animals; Blood Pressure; Corn Oil; Diet; Disease Models, Animal; Fatty Acids; Fatty Acids, Unsaturated; Fish Oils; Hypertension; Lipid Peroxidation; Male; Peroxides; Rats; Rats, Inbred Strains; tert-Butylhydroperoxide; Thromboxane A2; Vitamin E

The present study was designed to point out similarities between the effects on pulmonary circulation caused by hypoxia and by a chemoreceptor stimulant (S1867, an almitrine analog). Isolated rat lungs were perfused at a constant flow with homologous blood and ventilated under normoxic, hypoxic or hyperoxic conditions. (1) At 0.25 microgram/ml, S1867 potentiated the hypoxic pressor response, while at 1 microgram/ml, it induced a significant increase in pulmonary artery pressure (PAP) at 21% O2. (2) Since the expression of an oxygen-binding protein (NADPH-oxidase like) has been demonstrated in the rat carotid bodies, we studied the effects of the NADPH-oxidase inhibitor diphenyleneiodonium (DPI) on HPV and on S1867-induced pulmonary vascular responses. Both responses were totally abolished by DPI (40 microM), whereas the vasoconstriction induced by a thromboxane A2 analog (U46619) remained unchanged. (3) Vascular responses to hypoxia and S1867 (1 microgram/ml) were both reversed by a bolus of the sulfhydryl oxidant diamide (3 mg). (4) The S1867-induced response was prevented and reversed by the supply of inhaled oxygen, which was without action on the vasoconstriction induced by U46619. These results suggest that the almitrine analog and hypoxia act at least partly through the same cellular mechanism, involving a DPI-sensitive protein.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Almitrine; Animals; Blood Pressure; Chemoreceptor Cells; Disease Models, Animal; Enzyme Inhibitors; Hypoxia; In Vitro Techniques; Male; NADPH Oxidases; Nitric Oxide Synthase; Onium Compounds; Perfusion; Prostaglandin Endoperoxides, Synthetic; Pulmonary Artery; Pulmonary Circulation; Rats; Rats, Sprague-Dawley; Respiratory System Agents; Thromboxane A2; Vasoconstriction

We examined the effects of diabetes on eicosanoid metabolism and endothelium-dependent relaxation in isolated aorta from alloxan-induced diabetic rabbits and that from normal rabbits incubated in increased concentrations (44 mM) of glucose in vitro for 6 h. Immunoreactive 15-hydroxyeicosatetraenoic acid (HETE) was assayed in the incubation media of isolated aortic segments. Basal and acetylcholine (ACh)-stimulated release of 15-HETE was significantly greater in aorta of diabetic animals as compared with those of normal rabbits. Incubation of aortic segments from normal rabbits in increased concentrations of glucose caused a significant increase in basal and ACh-stimulated release of 15-HETE; and the release was significantly greater in aortic segments with endothelium than in segments without endothelium. Basal and ACh-stimulated release of 15-HETE was inhibited by indomethacin, a cyclooxygenase inhibitor. 15-HETE caused contractions of aortic rings that were inhibited by the prostaglandin H2 (PGH2) thromboxane A2 (TXA2) receptor blocker SQ-29548, but not by the TXA2 synthase inhibitor carbethoxyhexyl imidazole or indomethacin. Treatment of aortic rings with subthreshold concentrations of 15-HETE impaired ACh-induced relaxation; this was prevented by treatment with SQ-29548. Thus, abnormal release of endothelium-derived 15-HETE may play a role in endothelial cell dysfunction and increased vasoconstriction in diabetes by a mechanism that involves interaction with PGH2/TXA2 receptors.

Topics: Acetylcholine; Animals; Aorta, Abdominal; Bridged Bicyclo Compounds, Heterocyclic; Cytochrome P-450 Enzyme Inhibitors; Diabetes Mellitus, Experimental; Disease Models, Animal; Endothelium, Vascular; Fatty Acids, Unsaturated; Glucose; Hydrazines; Hydroxyeicosatetraenoic Acids; Imidazoles; Indomethacin; Male; Muscle Contraction; Muscle, Smooth, Vascular; Proadifen; Prostaglandin H2; Prostaglandins H; Rabbits; Radioimmunoassay; Superoxide Dismutase; Thromboxane A2

The hemodynamic effects of endothelin-1 (ET-1) are mediated by at least two distinct receptors: ETa and ETb receptors. Recently, ETb receptor agonists (4 Ala ET-1 and IRL 1620) were developed. To investigate the role of ETb receptor activation on the pulmonary and systemic circulations, we studied the hemodynamic effects of intrapulmonary arterial injections of these receptor agonists in 10 intact newborn lambs. At rest, 4 Ala ET-1 (290-1,725 ng/kg) changed no hemodynamic variables. IRL 1620 (180-1,095 ng/kg) decreased mean pulmonary arterial pressure (PAP, 16.8% +/- 15.0 and 17.8% +/- 8.5, p < 0.05) and left pulmonary artery blood flow (21.6% +/- 22.1 and 33.4% +/- 27.7, p < 0.05) at the two highest doses only. During U46619-induced pulmonary hypertension, both 4 Ala ET-1 (3.2% +/- 8.0 to 15.9% +/- 6.4, p < 0.05) and IRL 1620 (8.7% +/- 6.3 to 21.9% +/- 4.1, p < 0.05) produced selective dose-dependent decreases in PAP. The decrease in mean PAP induced by 4 Ala ET-1 and IRL 1620 was attenuated by N omega-nitro-L-arginine [an inhibitor of endothelium-derived nitric oxide (EDNO) synthesis] (16.6% +/- 3.5 vs. 5.9% +/- 2.3 and 16.2% +/- 3.4 vs. 6.6% +/- 2.8, p < 0.05) and by glybenclamide (a blocker of ATP-dependent potassium channels) (18.2% +/- 7.9 vs. 7.5% +/- 8.3 and 14.7% +/- 3.6 vs. 6.3% +/- 3.2, p < 0.05). ETb receptor activation produces selective pulmonary vasodilation during pulmonary hypertension in intact newborn lambs. The vasodilating properties are mediated in part by release of ENDO and by potassium channel activation.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Animals, Newborn; Arginine; Blood Pressure; Disease Models, Animal; Endothelins; Endothelium, Vascular; Glyburide; Hypertension, Pulmonary; Injections, Intra-Arterial; Nitroarginine; Peptide Fragments; Prostaglandin Endoperoxides, Synthetic; Pulmonary Artery; Pulmonary Circulation; Regional Blood Flow; Sheep; Thromboxane A2; Vascular Resistance; Vasoconstrictor Agents; Vasodilation

Thromboxane A2 (TxA2) seems to play an important role in bronchial constriction and hypersensitivity in asthmatics. To study the role of TxA2 in allergic rhinitis, we investigated the levels of thromboxane B2 (TxB2), a stable metabolite of TxA2, in nasal lavage fluid from patients with allergic rhinitis and from actively sensitized guinea pigs after antigen challenge by radioimmunoassay (RIA). There was a significant (p < 0.05) rise in TxB2 levels soon after antigen challenge in nasal lavage fluid from both patients (36.4 +/- 7.5 pg/ml, mean +/- SE) and models (55.6 +/- 21.8 pg/ml). In some of the patients and models, there was an dual rise in TxB2 in the 10 hours after antigen challenge. There was a significant (p < 0.03) correlation between the patients whose levels of TxB2 were re-elevated and them whose nasal airway resistance showed dual rises. These results suggest that TxA2 may contribute to the nasal obstruction in later phase in allergic rhinitis.

Topics: Adult; Animals; Antigens; Disease Models, Animal; Female; Guinea Pigs; Humans; Male; Nasal Lavage Fluid; Nasal Obstruction; Radioimmunoassay; Rhinitis, Allergic, Perennial; Thromboxane A2; Thromboxane B2

The cardiopulmonary response elicited by intravenous bacteria or endotoxin is well characterized in swine and has two major components. The first represents the acute pulmonary and broncho-constrictive phase (0-2 h) and the second phase (3-8 h) represents increased microvascular permeability, hypotension, and enhanced leukocyte-endothelial adhesion. The pulmonary vasoconstriction and bronchoconstriction of phase 1 results in acute pulmonary hypertension and airway dysfunction, which may result in rapid mortality. Because this acute pulmonary response may not mimic the development of human septic shock, we sought to block this early phase and examine the role of tumor necrosis factor in the latter septic phase (3-8 h). Employing a thromboxane A2 (TXA2) receptor antagonist (BAY U 3405) in the presence of LD100 Escherichia coli challenge, we blocked the acute pulmonary hypertensive phase and prevented early mortality, however, TXA2 blockade did not affect the latter development of septic shock and death. This latter lethal phase, characterized by prolonged leukopenia, was blocked in a dose-dependent manner by tumor necrosis factor monoclonal antibody. We conclude that the TXA2-blocked E. coli-challenged swine may provide a novel animal model in which to investigate the pathophysiology of acute septic shock.

Topics: Animals; Antibodies, Monoclonal; Bronchoconstriction; Capillary Permeability; Carbazoles; Disease Models, Animal; Dose-Response Relationship, Drug; Escherichia coli; Inflammation; Leukocytes; Leukopenia; Lung; Platelet Aggregation Inhibitors; Pulmonary Circulation; Receptors, Thromboxane; Shock, Septic; Sulfonamides; Swine; Thromboxane A2; Tumor Necrosis Factor-alpha; Vasoconstriction

There were no differences between mesenteric arteries from sham or 14-day portal hypertensive (PH) rats in the potency of or maximum endothelium-dependent relaxations (EDR) to acetylcholine. There were no differences between sham-operated and PH rats in the effects of the combination of the nitric oxide synthase inhibitor NG-monomethyl-L-arginine (100 mumol/l) and methylene blue (10 mumol/l) in causing a significant reduction in the EDR to acetylcholine. The degree of portal-systemic shunting, as measured by 57Co-labeled microspheres, was unaffected by acute administration of NG-monomethyl-L-arginine (50 mg/kg) or methylene blue (5 mg/kg). In conclusion, nitric oxide is the main mediator of EDR in rat mesenteric artery, and no evidence was found for an increased role for endothelial-derived nitric oxide in PH rats.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Acetylcholine; Analysis of Variance; Animals; Coloring Agents; Disease Models, Animal; Endothelium, Vascular; Hypertension, Portal; Male; Mesenteric Arteries; Methylene Blue; Microspheres; Muscle Contraction; Muscle Relaxation; Muscle, Smooth, Vascular; Nitric Oxide; Nitric Oxide Synthase; omega-N-Methylarginine; Prostaglandin Endoperoxides, Synthetic; Rats; Rats, Wistar; Thromboxane A2; Vasoconstrictor Agents

Etodolac, which inhibits the activity of cyclooxygenase, did not affect antigen-induced contractions of the trachea and lung parenchyma of guinea pigs. Indomethacin tended to enhance antigen-induced contractions of the trachea and significantly enhanced contractions of the lung parenchyma. The inhibitory activity of AA-861, a 5-lipoxygenase inhibitor, in antigen-induced contractions of the trachea and lung parenchyma was more potent than that of ozagrel, a thromboxane A2 (TXA2) inhibitor. Thus, lipoxygenase products played a more important role than TXA2 in antigen-induced contractions of the trachea and lung parenchyma. These results suggest that the enhancement of antigen-induced contractions by indomethacin might be due to an increase in anaphylactic release of lipoxygenase products through the inhibition of cyclooxygenase. Since etodolac did not enhance antigen-induced contractions, we attempted to determine whether or not etodolac inhibits 5-lipoxygenase. Etodolac was found to have no effect on 5-lipoxygenase activity. Therefore, the low adverse effect of etodolac on antigen-induced contractions of the airway may be due to its weak inhibition of cyclooxygenase in the airway. These results suggest that etodolac would have only a very slight, if any, adverse effect on the airway in patients with asthma.

Topics: Animals; Asthma; Benzoquinones; Disease Models, Animal; Etodolac; Guinea Pigs; Immunization, Passive; Indomethacin; Isoantigens; Lipoxygenase Inhibitors; Lung; Methacrylates; Muscle Contraction; Muscle, Smooth; Rabbits; Serum Albumin, Bovine; Thromboxane A2; Trachea

Topics: Animals; Blood Pressure; Catecholamines; Constriction; Denervation; Disease Models, Animal; Hypertension, Renovascular; Kidney; Male; Nephrectomy; Potassium; Rats; Rats, Sprague-Dawley; Renal Artery; Sodium; Sympathetic Nervous System; Thromboxane A2; Thromboxane B2

Plasma 6-keto-prostaglandin F1 alpha and thromboxane B2 levels were determined to evaluate their role as predictive indicators for the development and progression of coronary atherosclerosis in young hypercholesterolemic swine. 32 young swine were randomly assigned to the control or atherogenic diet group for 10, 30, 90, or 180 days. Lipid profiles were obtained at the onset and repeated throughout the study. Radioimmunoassays of plasma 6-keto-prostaglandin F1 alpha and thromboxane B2 were recorded at 10 day intervals in the 10 and 30 day subjects and at 30 day intervals in the 90 and 180 day subjects. Sections from the proximal left anterior descending coronary artery were classified based on their histological evidence of atherosclerosis by light microscopy. Hypercholesterolemia was positively correlated with development of coronary atherosclerosis (r = 0.704). However, plasma 6-keto-prostaglandin F1 alpha, thromboxane B2, and the thromboxane B2:6-keto-prostaglandin F1 alpha ratio were not found to be predictive indicators (p > 0.05) for the development or early progression of coronary atherosclerosis.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Arteriosclerosis; Body Weight; Diet, Atherogenic; Disease Models, Animal; Epoprostenol; Female; Hematocrit; Hypercholesterolemia; Lipids; Male; Random Allocation; Risk Factors; Swine; Thromboxane A2; Thromboxane B2

We have previously shown that rats with congenital, unilateral hydronephrosis exhibit a reduction in GFR that returns to normal when either the renin angiotensin system or thromboxane A2 (TxA2) is blocked. The current study defines the single nephron defect in congenital, unilateral hydronephrosis and evaluates the roles of angiotensin II (Ang II) and TxA2 in this renal derangement. Renal micropuncture experiments were performed on the right kidney of rats from an inbred colony with unilateral right-sided hydronephrosis (HYDRO), or non-affected litter mates (CONTROL). In addition, four separate groups of hydronephrotic animals were treated with either the TxA2 receptor antagonist SQ-29548 (SQ), one of two Ang II receptor antagonists [saralasin (SAR) or DuP-753 (DUP)]; or combined treatment with DuP-753 and SQ-29,548 (S&D). SNGFR was significantly reduced (P < 0.05) in HYDRO compared to CONTROL (17.6 +/- 2.0 vs. 35.9 +/- 3.7 nl/min, respectively). Treatment with SQ-29,548 normalized SNGFR (29.0 +/- 3.0 nl/min), while saralasin and DuP-753 resulted in only a partial recovery of function (25.6 +/- 1.6 and 27.8 +/- 1.4 nl/min, respectively). Combined SQ-29,548 and DuP-753 treatment resulted in full recovery of SNGFR to 32.9 +/- 4.4 nl/min. The glomerular ultrafiltration coefficient (Kf) was reduced (P < 0.05) approximately 45% in HYDRO compared to CONTROL (1.64 +/- .08 vs. 2.84 +/- .22 nl/min/mm Hg, respectively). Kf returned to control levels in SAR, DUP and SQ, and increased above control in S&D (5.58 +/- 1.6 nl/min/mm Hg). There were no differences (P > 0.05) in hydrostatic or oncotic pressures across the glomerular capillary between any of the groups studied. The observation that Kf increases above CONTROL with combined blockade of TxA2 and Ang II suggests that these regulatory hormones decrease Kf via independent mechanisms. These data indicate that the reduction in SNGFR in congenital, unilateral hydronephrosis is a result of a marked fall in Kf that is mediated by both Ang II and TxA2.

Topics: Angiotensin II; Animals; Biphenyl Compounds; Bridged Bicyclo Compounds, Heterocyclic; Disease Models, Animal; Fatty Acids, Unsaturated; Glomerular Filtration Rate; Hydrazines; Hydronephrosis; Imidazoles; Kidney Glomerulus; Losartan; Male; Rats; Rats, Inbred Strains; Rats, Wistar; Saralasin; Tetrazoles; Thromboxane A2

We studied the effect of KW-3635, a selective thromboxane A2 (TXA2)-receptor antagonist, on experimental glomerulonephritis. The glomerulonephritis was induced in mice by the administration of rabbit anti-mouse glomerular basement membrane (GBM) antibody. It was characterized as proteinuria, changes of serum biochemical parameters and glomerular histopathological abnormalities. The administration of KW-3635 (30 mg/kg/day, p.o.) significantly ameliorated the proteinuria, elevation of serum urea nitrogen and the thickening of GBM. These data suggest that TXA2 may play an important pathogenic role in the development and progression of glomerulonephritis.

Topics: Animals; Antibodies, Monoclonal; Basement Membrane; Benzimidazoles; Benzoxepins; Blood Urea Nitrogen; Disease Models, Animal; Glomerulonephritis; Kidney Glomerulus; Male; Mice; Proteinuria; Thromboxane A2

Antithrombotic effects of KW-3635, a newly synthesized thromboxane (TX) A2-receptor antagonist, were studied in guinea pigs. In the extracorporeal circulation thrombosis model, the shunt was filled with thrombi, and reduction of platelet count and increase in plasma TXA2 concentration were observed. KW-3635 (30 and 100 mg/kg, p.o.) inhibited the thrombus formation in the shunt and prevented the decrease in platelet count in the circulating blood without affecting the red blood cell count. BM13,505 (30, 100 mg/kg, p.o.), another TXA2-receptor antagonist, and ticlopidine (300 mg/kg, p.o.), an antiplatelet drug, also inhibited the thrombus formation, while aspirin (10, 300 mg/kg, p.o.) did not. Peripheral arterial occlusive disease was induced by injection of sodium laurate into the femoral artery in guinea pigs. Daily oral administration of KW-3635 (3-30 mg/kg) significantly prevented the progression of vascular lesions. BM13,505 (3-30 mg/kg, p.o.) and ticlopidine (100 mg/kg, p.o.) also ameliorated the vascular lesions, whereas aspirin (10, 100 mg/kg, p.o.) did not. KW-3635 at concentrations up to 10(-4) M did not affect coagulation parameters in vitro. These results suggest that TXA2 is involved in the pathogenesis of arterial thrombotic and ischemic disorders. KW-3635 may be useful for the treatment of thrombotic disease and peripheral arterial occlusive diseases.

Topics: Animals; Arterial Occlusive Diseases; Aspirin; Benzimidazoles; Benzoxepins; Blood Coagulation; Blood Platelets; Disease Models, Animal; Erythrocyte Count; Femoral Artery; Guinea Pigs; Lauric Acids; Male; Phenylacetates; Platelet Count; Sulfonamides; Thrombosis; Thromboxane A2; Thromboxanes; Ticlopidine

Long-lasting bronchial hyperresponsiveness to i.v. acetylcholine was observed in actively sensitized guinea-pigs after aerosol ovalbumin exposure. The response became significant at 7 h post-challenge and persisted for at least 120 h compared to the response of unsensitized animals. Pretreatment of animals with the specific thromboxane A2 receptor antagonist, S-1452 (calcium (1R,2S,3S,4S)-(5Z)-7-(((phenylsulfonyl)amino)bicyclo[2.2.1] hept-2-yl)hept-5-enoate dihydrate), almost completely inhibited the onset of bronchial hyperresponsiveness, as assessed at 24 and 120 h post-challenge. However, it was ineffective when administered at 1 h post-challenge or 2 h before assessment of bronchial responsiveness. Lung vascular injury occurred transiently immediately after antigen challenge, the kinetics of injury being associated with those for the production of thromboxane B2 in bronchoalveolar lavage fluid. The vascular injury was dramatically suppressed by pretreatment with S-1452. These findings suggest that acutely generated thromboxane A2 plays an important role in the pathogenesis of antigen-induced long-lasting bronchial hyperresponsiveness, probably by producing vascular damage in the lungs.

Topics: Acetylcholine; Administration, Inhalation; Aerosols; Animals; Asthma; Bridged Bicyclo Compounds; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Disease Models, Animal; Endothelium, Vascular; Fatty Acids, Monounsaturated; Guinea Pigs; Immunization; Injections, Intravenous; Lung; Male; Ovalbumin; Prostaglandins; Pulmonary Artery; Receptors, Prostaglandin; Thromboxane A2

The anti-anginal effect of nitroglycerin and prostacyclin was examined using, as an index, the ischaemic electrocardiogram (ECG) change (ST elevation) induced by intracoronary arterial injection of 9,11-dideoxy-11 alpha,9 alpha-epoxymethano-PGF2 alpha (U-46619), a stable thromboxane A2 agonist, in anaesthetized rats. The ST elevation induced by U-46619 (5-20 micrograms kg-1, i.c.a.) was dose-dependent and reproducible. U-46619-induced ST elevation was markedly prevented by the pretreatment of intravenous administration of prostacyclin (0.01 micrograms kg-1), and to a lesser extent by nitroglycerin (0.3 mg kg-1). Simultaneously, platelet count decreased significantly in the coronary arterial blood which indicated that platelet aggregation was enhanced by U-46619. The decrease of platelet count in coronary arterial blood at the time of ST elevation was significantly suppressed by prostacyclin (0.1 microgram kg-1, i.v.), but not by nitroglycerin (0.3 mg kg-1, i.v.). These results suggest that the ST elevation induced by intracoronary arterial injection of U-46619 may be derived from spasm of coronary artery and platelet aggregation in the intracoronary artery in rats.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Analysis of Variance; Animals; Blood Platelets; Blood Pressure; Coronary Vessels; Disease Models, Animal; Electrocardiography; Epoprostenol; Heart Rate; Injections, Intra-Arterial; Injections, Intravenous; Male; Myocardial Ischemia; Nitroglycerin; Platelet Aggregation; Platelet Count; Prostaglandin Endoperoxides, Synthetic; Rats; Rats, Sprague-Dawley; Thromboxane A2; Vasoconstrictor Agents

Although it is well recognized that beta-blockers can induce bronchoconstriction only in patients with asthma, mechanisms of the bronchoconstriction are not well known. We hypothesize that bronchoconstriction induced by beta-blockers may result from inflammatory mediators released by allergic reactions. In this study, we developed a guinea pig model for propranolol-induced bronchoconstriction (PIB) after antigen inhalation and investigated the effect of specific thromboxane (TXA2) receptor antagonists, S-1452 and ONO NT-126, on PIB in passively sensitized and artificially ventilated guinea pigs to determine whether TXA2 is involved in PIB. Propranolol caused bronchoconstriction with 10 mg/ml of propranolol was inhaled 20 min after antigen challenge. On the other hand, propranolol did not produce bronchoconstriction after antigen provocation in nonsensitized guinea pigs or after saline provocation in sensitized animals. Pretreatment of the animals with S-1452 in doses of 0.01 and 0.1 mg/kg and ONO NT-126 in doses of 1.0 and 10 micrograms/kg injected intravenously 15 min after antigen challenge as well as before antigen challenge reduced PIB in a dose-dependent manner. Bronchoconstriction caused by methacholine did not induce PIB. These results suggest that TXA2 has an important role in the pathophysiology of the PIB that develops after the allergic bronchoconstriction.

Topics: Administration, Inhalation; Analysis of Variance; Animals; Asthma; Bridged Bicyclo Compounds; Bronchial Provocation Tests; Constriction, Pathologic; Disease Models, Animal; Dose-Response Relationship, Drug; Fatty Acids, Monounsaturated; Guinea Pigs; Hypersensitivity; Inflammation; Injections, Intravenous; Male; Methacholine Chloride; Premedication; Propranolol; Receptors, Prostaglandin; Thromboxane A2; Time Factors

We established an experimental model of late asthmatic response (LAR) using conscious guinea pigs actively sensitized by antigen aerosol inhalation. In actively sensitized guinea pigs, antigen challenge by aerosol inhalation caused an immediate increase in specific airway resistance (SRaw) (immediate airway response; IAR) followed by a LAR which occurred 4 to 8 hr after antigen challenge. SRaw in the challenged animals was still increased 23 hr after antigen challenge. Examination of bronchoalveolar lavage (BAL) fluid and histology of the lungs revealed increases in eosinophils and neutrophils during LAR. The beta-2 agonist salbutamol inhibited only IAR and not LAR. Dexamethasone inhibited LAR but not IAR. A low dose of theophylline had little effect on both IAR and LAR. A novel thromboxane A2 (TXA2) receptor antagonist, AA-2414, orally administered before antigen challenge dose-dependently inhibited both IAR and LAR, and oral administration of AA-2414 after the IAR inhibited LAR. Also, thromboxane synthetase inhibitors, CV-4151 and OKY-046, reduced both IAR and LAR. Salbutamol significantly reduced the increase in neutrophils in BAL fluid, and dexamethasone significantly reduced the increase in eosinophils and neutrophils in BAL fluid. Theophylline also reduced the increase in eosinophils in BAL fluid. However, AA-2414 did not inhibit the accumulation of these inflammatory cells in BAL fluid or the airway tissues. These results suggest that asthmatic responses in guinea pigs are similar to those in asthmatic subjects and that TXA2 plays an important role in both IAR and LAR but not in inflammatory cell infiltration in this model of allergic asthma.

Topics: Acetylcholine; Airway Resistance; Animals; Antibodies; Asthma; Benzoquinones; Bronchoalveolar Lavage Fluid; Disease Models, Animal; Fatty Acids, Monounsaturated; Guinea Pigs; Heptanoic Acids; Leukocytes; Male; Methacrylates; Ovalbumin; Pyridines; Theophylline; Thromboxane A2

Early-onset neonatal group B beta-hemolytic streptococcus (GBS) infection exhibits pathophysiologic characteristics of a toxic shock syndrome, in which a cascade of inflammatory mediators are involved. Thromboxane A2 (TXA2) is thought to play an important role as a mediator of the pulmonary response to GBS toxin, because high lung lymph concentrations of a TXA2 metabolite have been observed after GBS toxin injections in sheep. The aim of this study was to evaluate the effects of a selective antagonist of the TXA2-prostaglandin endoperoxide receptor (SQ 29,548). Six unanesthetized young lambs, each serving as its own control, were given SQ 29,548 or vehicle control followed by GBS toxin challenge. Hemodynamic and lung function (lung mechanics, lung volume, ventilation) responses were followed for 5 h. When compared with the control studies, treatment with SQ 29,548 significantly altered the response to GBS toxin. SQ 29,548 reduced the increase in pulmonary and systemic vascular resistance, improved cardiac output and stroke volume, improved dynamic lung compliance but not airway resistance, and improved oxygenation. The attenuating effect of SQ 29,548 was most pronounced during the first phase of toxin response (15-90 min after toxin infusion), but significant treatment effects were also seen during the second phase (120-300 min after toxin infusion). This study demonstrates that TXA2 is an important mediator of the response to GBS toxin and is responsible for hemodynamic and lung function changes. Thromboxane receptor blockade may offer a potential therapeutic approach to infants with severe early-onset GBS sepsis.

Topics: Airway Resistance; Animals; Bacterial Toxins; Bridged Bicyclo Compounds, Heterocyclic; Cardiac Output; Disease Models, Animal; Fatty Acids, Unsaturated; Hemodynamics; Hydrazines; Lung; Pulmonary Gas Exchange; Receptors, Thromboxane; Respiratory Mechanics; Sheep; Streptococcal Infections; Streptococcus agalactiae; Stroke Volume; Thromboxane A2; Vascular Resistance

We investigated the possible protective effects of benidipine (Coniel), a calcium antagonist, on mechanical dysfunction, metabolic damage and changes in vascular reactivity during ischemia and reperfusion in the Langendorff-perfused rat heart. The responses of perfusion pressure to U-46619, a vasoconstrictor, and acetylcholine, an endothelial-dependent vasodilator, were also determined as indices of the vascular function. Thirty min of reperfusion following 30 min of global ischemia produced contractile failure and the marked release of lactate dehydrogenase (LDH) and creatine phosphokinase (CPK). Additionally, the ischemia and reperfusion augmented the vasoconstrictor response to U-46619, and depressed the endothelium-dependent vasodilator response to acetylcholine. These hearts were treated with 1 or 10 nM benidipine from 20 min before ischemia to the beginning of ischemia. While benidipine at 10 nM had a modest negative inotropic action, 1 nM of this drug had minimal depressant effects on the preischemic function. The depressed contractile function after the ischemia was improved, and the increased releases of LDH and CPK were significantly ameliorated by benidipine. Also, benidipine restored the augmented contractile response to U-46619 and preserved the vasodilator response to acetylcholine. These results demonstrate that pretreatment with benidipine prevents myocardial injury following ischemia and reperfusion. The cardioprotective effects of benidipine may in part be due to the protection of vascular reactivity by this drug.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Acetylcholine; Animals; Calcium Channel Blockers; Dihydropyridines; Disease Models, Animal; In Vitro Techniques; Male; Myocardial Contraction; Myocardial Ischemia; Myocardial Reperfusion Injury; Prostaglandin Endoperoxides, Synthetic; Rats; Rats, Wistar; Thromboxane A2; Vascular Resistance; Vasoconstrictor Agents

Topics: Animals; Arachidonic Acids; Disease Models, Animal; Dogs; Embolism, Fat; Epoprostenol; Female; Hypoxia; Indomethacin; Lung; Lung Injury; Male; Methacrylates; Microcirculation; Oleic Acid; Oleic Acids; Pulmonary Circulation; Pulmonary Embolism; Respiratory Distress Syndrome; Thromboxane A2; Vasoconstriction; Vasodilation

The antithrombotic effects of the thromboxane (TX) A2-receptor antagonist and aspirin were determined using a photochemically-induced arterial thrombosis model in the femoral arteries of guinea pigs. KW-3635 (sodium (E)-11-[2-(5,6-dimethyl-1-benzimidazolyl)ethylidene]-6,11- dihydrodibenz[b,e]-oxepine-2-carboxylate monohydrate) and BM-13505, both of which are TXA2-receptor antagonists, and aspirin inhibited the thrombus formation at the doses that inhibited the ex vivo platelet aggregation induced by sodium arachidonate (100 microM) or collagen (3 micrograms/ml). These results support the notion that TXA2 is an important mediator in the present model of arterial thrombogenesis.

Topics: Animals; Arachidonic Acid; Aspirin; Benzimidazoles; Benzoxepins; Collagen; Disease Models, Animal; Femoral Artery; Guinea Pigs; Male; Phenylacetates; Platelet Aggregation; Sulfonamides; Thrombosis; Thromboxane A2

The effects of CV-4151 on post-ischemic brain hypoperfusion and thromboxane (Tx)A2 production in a canine model of total global brain ischemia were studied. Complete cerebral ischemia for 5 min was produced in adult mongrel dogs by temporary ligation of the venae cavae and aorta. In the non-treated group, cerebral blood flow (CBF) increased during the first 20 to 30 min post-ischemia followed by a gradual decline and then stayed below preischemic level; CBF at 2 hr after the reperfusion was significantly reduced to ca 77% of the pre-ischemic level. Water content in the cerebral cortex at 2 hr after the reperfusion in the non-treated group was 78.15 +/- 0.21%, higher than the content in the control group, 76.70 +/- 0.07%. The concentration of TxB2 in the sagittal sinus was significantly increased at 30 min post ischemia. CV-4151 (1.0 mg/kg, i.v.) almost completely inhibited the post-ischemic hypoperfusion, significantly inhibited the increase in water content and almost completely inhibited the production of TxB2 in the post-ischemic period and increased the production of 6-keto PGF1 alpha. OKY-046 (10 mg/kg, i.v.) had no significant effects on both post-ischemic hypoperfusion and increase in water content in the cerebral cortex. We conclude that CV-4151 ameliorates post-ischemic cerebral hypoperfusion and that this improvement is associated with decreased sagittal sinus levels of TxB2.

Topics: Animals; Body Water; Brain Ischemia; Cerebral Cortex; Cerebrovascular Circulation; Disease Models, Animal; Dogs; Fatty Acids, Monounsaturated; Female; Male; Pyridines; Reperfusion Injury; Thromboxane A2; Thromboxane-A Synthase

The anti-asthmatic effects of CS-518 (sodium 2-(1-imidazolylmethyl)-4,5-dihydrobenzo[b]thiophene-6-carboxylate) , a specific thromboxane A2 (TXA2) synthase inhibitor, were investigated in the ovalbumin-sensitized guinea pig asthmatic model. Although CS-518 slightly inhibited (about 25%) whole bronchoconstriction, it significantly inhibited the antigen-induced bronchoconstriction mediated by slow-reacting substance of anaphylaxis (SRS-A), which was not reduced by chlorpheniramine, a histamine H1 antagonist. On the other hand, indomethacin, a cyclooxygenase inhibitor, potentiated the SRS-A-mediated constriction. CS-518 strongly, and indomethacin slightly, suppressed the leukotriene D4-induced bronchoconstriction. CS-518 clearly inhibited the antigen-induced airway hyperresponsiveness, but this compound had no effect on the airway hyperresponsiveness induced by U-46619, a TXA2-mimetic agent, and propranolol. These results suggest that CS-518 suppresses the development of bronchoconstriction and airway hyperresponsiveness in asthmatic models by inhibition of TXA2 synthesis with the concomitant increase in bronchodilating prostaglandins such as prostaglandin E2 and prostaglandin I2.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Asthma; Bronchial Hyperreactivity; Bronchoconstriction; Chlorpheniramine; Disease Models, Animal; Guinea Pigs; Indomethacin; Male; Methacrylates; Ovalbumin; Propranolol; Prostaglandin Endoperoxides, Synthetic; SRS-A; Thiophenes; Thromboxane A2; Thromboxane-A Synthase; Vasoconstrictor Agents

The present studies were undertaken to determine the interactions between halothane and oxidative injury with respect to endothelial integrity, as measured by pulmonary capillary filtration coefficient (Kfc), and production of arachidonic acid-derived mediators, in perfused rabbit lungs challenged with the oxidant tert-butyl-hydroperoxide (t-bu-OOH).. Isolated lungs were prepared from 27 New Zealand white rabbits (2-3 kg) and were perfused with Ca(2+)-free Krebs-Henseleit buffer solution. In group A (n = 9), lungs were ventilated with halothane 2.5% in carrier gas (5% CO2 in air); in group B (n = 9), with carrier gas alone; and in group C (n = 9), with carrier gas, but without injury. The lungs in the two injury groups (A and B) received four infusions of t-bu-OOH, 200 microM, over 1 min, directly into the pulmonary artery. The uninjured lungs received four infusions of vehicle (normal saline). Kfc was determined after each t-bu-OOH infusion. Concentrations of thromboxane B2 (TxB2) and 6-keto-prostaglandin F1 alpha were measured in samples of effluent perfusate obtained before and 30 s after the end of each infusion of t-bu-OOH. The wet/dry weight ratio of each pair of lungs was determined at the end of each experiment.. Kfc progressively increased after each infusion of oxidant in group A when compared with the other two groups. Lung wet/dry ratios were elevated in group A (14.3 +/- 0.7) and group B (13.2 +/- 0.2) compared with group C (12.1 +/- 1.1). TxB2 production in group A (2206 +/- 263 pg.min-1.g-1 dry lung tissue) was greater than in group B (1413 +/- 127) by the final infusion of t-bu-OOH.. Ex vivo perfused rabbit lungs ventilated with halothane exhibited, simultaneously, evidence of greater fluid conductance across the pulmonary capillary bed and production of thromboxane A2 when challenged with oxidant than did lungs ventilated with carrier gas. Both of these effects may be mediated by halothane-related enhancement of intracellular endothelial Ca2+ mobilization stimulated by intrapulmonary infusion of oxidant.

Topics: Animals; Body Fluids; Buffers; Disease Models, Animal; Drug Interactions; Eicosanoids; Epoprostenol; Halothane; Lung; Male; Peroxides; Pneumonia; Pulmonary Alveoli; Pulmonary Edema; Rabbits; tert-Butylhydroperoxide; Thromboxane A2

We investigated the effect of G 619, a dual thromboxane synthase inhibitor and thromboxane A2 (TxA2) receptor antagonist, in pentobarbital-anaesthetized rats subjected to left main coronary artery ligation (1 h) followed by reperfusion (1 h; MI/R). Sham-operated rats were used as controls (sham MI/R). Survival rate, myocardial necrosis, myocardial myeloperoxidase (MPO) activity (investigated as an index of leukocyte adhesion and accumulation) and serum creatine phosphokinase (CPK) activity were studied. MI/R injury significantly reduced survival rate (45%), caused a marked myocardial necrosis, increased serum CPK activity (sham MI/R = 35 +/- 12 U/ml; MI/R = 205 +/- 13 U/ml) and produced an increase in myocardial MPO activity in the area at risk and in the necrotic area (6.3 +/- 0.5 and 6.6 +/- 0.9 U x 10(-3)/g tissue, respectively). The administration of G 619 significantly increased survival rate, lowered the area of necrosis, blunted the increase in serum CPK activity and reduced the increase in MPO activity in both the area at risk and the necrotic area. These data are consistent with an involvement of TxA2 in MI/R injury and suggest that G 619 may represent a novel therapeutic approach to the treatment of acute myocardial infarction.

Topics: Animals; Benzamides; Coronary Disease; Creatine Kinase; Disease Models, Animal; Leukocyte Count; Male; Myocardial Infarction; Myocardial Reperfusion Injury; Neutrophils; Peroxidase; Picolines; Rats; Rats, Sprague-Dawley; Receptors, Thromboxane; Survival Rate; Thromboxane A2; Thromboxane-A Synthase

Several attempts have been undertaken to reduce the severity of ischemic myocardial injury by exogenous administration of eicosanoids and by modification of endogenous eicosanoid production. The present study investigates whether defibrotide, a compound that stimulates endogenous prostacyclin (PGI2), has a beneficial effect in experimental ischemic myocardial injury. Anesthetized, open-chest minipigs were subjected to 1 h of coronary artery occlusion, followed by 3 h of reperfusion. Defibrotide (32 mg/kg x h) or its vehicle were infused i.v. throughout the experiment. Defibrotide increased cardiac PGI2 formation 3- to 4-fold greater than control (P < .05). Thromboxane levels remained unchanged. Irreversible ischemic injury, as identified by negative tetrazolium staining, amounted to 44 +/- 6% of the area at risk in pigs receiving vehicle but was reduced to 23 +/- 4% by defibrotide (P < .05). This reduced tissue injury in defibrotide-treated pigs was associated with improved functional recovery (left ventricular pressure, + dP/dtmax), during early reperfusion. Recovery did not occur in vehicle-treated pigs. Collagen (2 micrograms/ml)-induced platelet aggregation ex vivo was increased in vehicle-treated pigs during ischemia and reperfusion, but not in animals treated with defibrotide. Polymorphonuclear neutrophil leukocyte accumulation in the ischemic border zone was reduced from 59 +/- 17 cells/mm2 in vehicle-treated pigs to 17 +/- 9 cells/mm2 by defibrotide (P < .05). Pretreatment of the animals with indomethacin (3 mg/kg) prevented the reduction of infarct size and polymorphonuclear neutrophil leukocyte infiltration by defibrotide. Indomethacin increased infarct size in vehicle- and defibrotide-treated pigs by 71 and 59%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Blood Platelets; Cyclooxygenase Inhibitors; Disease Models, Animal; Epoprostenol; Female; Granulocytes; Indomethacin; Leukocyte Count; Male; Myocardial Infarction; Myocardial Ischemia; Myocardial Reperfusion Injury; Myocardium; Neutrophils; Platelet Count; Polydeoxyribonucleotides; Prostaglandins; Stimulation, Chemical; Swine; Swine, Miniature; Thromboxane A2; Ventricular Function, Left

The two objectives of this study were to assess the potential of BAY U 3405 to prevent arterial thrombosis in response to vessel wall injury and to determine the ability of BAY U 3405 to prevent thrombotic reocclusion after thrombolysis with anisoylated plasminogen streptokinase activator complex.. Dogs were instrumented with a carotid flow probe, stimulating electrode, and a stenosis. Current (150 microA) was applied to the intimal surface of the right carotid artery, and time to occlusive thrombus formation was noted. BAY U 3405 was administered, and the procedure for thrombus formation was repeated for the left carotid artery.. BAY U 3405 administration prevented occlusive arterial thrombosis formation. Ex vivo platelet aggregation was inhibited, bleeding time increased, and thrombus weight reduced after BAY U 3405 treatment. In a second group, thrombi were formed initially in both carotid arteries, BAY U 3405 was administered as before, and anisoylated plasminogen streptokinase activator complex was infused in the right carotid artery proximal to the occlusive thrombus. BAY U 3405 did not alter the incidence of rethrombosis compared with the lytic agent alone.. BAY U 3405 prevented primary arterial thrombosis, corresponding to inhibition of platelet aggregation, and increased bleeding times. BAY U 3405, however, did not prevent rethrombosis after successful thrombolysis with anisoylated plasminogen streptokinase activator complex, despite the fact that platelet reactivity was inhibited. The data are consistent with the concept that the residual thrombus represents a more effective thrombogenic stimulus as compared with arterial wall injury alone and that the mechanisms associated with primary versus secondary thrombus formation may require separate therapeutic approaches.

Topics: Animals; Carbazoles; Carotid Artery Thrombosis; Disease Models, Animal; Dogs; Male; Platelet Aggregation; Platelet Aggregation Inhibitors; Sulfonamides; Thromboxane A2

The mechanism of sulfur dioxide-induced bronchoconstriction was studied using isolated perfused and ventilated guinea-pig lungs. They were exposed to sulfur dioxide after pretreatment with different compounds, either via the pulmonary artery or via the air passages. Neither the cyclooxygenase inhibitor indomethacin (30 microM) nor the H1-receptor antagonist diphenhydramine (15 microM), given via the perfusate, attenuated the sulfur dioxide-induced bronchoconstriction. Furthermore, sulfur dioxide exposure did not cause a release of either thromboxane or histamine into the perfusate. In experiments with atropine equivocal results were obtained with regard to protection against sulfur dioxide-evoked bronchoconstriction. Intratracheal instillation of the local anesthetic agent lidocaine (1 mg/50 microliters) markedly reduced the sulfur dioxide-induced bronchoconstriction. Also, ruthenium red (10 microM), an agent with calcium entry-blocking properties and an inhibitor of capsaicin-induced bronchoconstriction, was able to inhibit the effect of sulfur dioxide. The sulfur dioxide-induced bronchoconstriction was associated with release of calcitonin gene-related peptide, a sensory neuropeptide. The effect of sulfur dioxide was also inhibited by a Ca(2+)-free buffer plus EGTA. These results suggest that sulfur dioxide-induced bronchoconstriction in the guinea-pig lung is the result of a local effect on sensory nerves (C-fiber activation). The mechanism seems to be dependent on the Ca(2+)-dependent release of sensory neuropeptides and to be linked to opening of the cation channel, which is associated with the proposed capsaicin receptor on sensory nerves as revealed by the inhibitory effect of ruthenium red.

Topics: Animals; Bronchoconstriction; Calcitonin Gene-Related Peptide; Disease Models, Animal; Guinea Pigs; Histamine; Lung; Male; Nerve Fibers; Ruthenium Red; Sensory Receptor Cells; Sulfur Dioxide; Thromboxane A2

The adaptation to periodic altitude hypoxia is known to have cardioprotective and antiarrhythmic effects in stress-induced and ischemic lesions. The effects are assumed to be associated with the enhanced activity of the body's stress-limiting systems, including prostaglandins (PG). Wistar rats were adapted in a hypobaric chamber at an altitude of 4000 m for 6 hours during 40 days. The levels of myocardial and plasma PGE, PGE2 alpha, PGI2, thromboxane A2 were measured by radioimmunoassay and those of plasma catecholamines by enzyme radioassay. In the myocardium, the adaptation showed a 2-fold increase in PGE levels, the PGE/PGE2 alpha ratio and PGI2 levels rose by 70 and 73%, respectively, the PGI2/thromboxane A2 ratio remaining unchanged, while thromboxane A2 concentrations also rose. In adaptation, the levels of PGE and PGI2 was 78 and 60% higher, respectively. In restraint stress, myocardial and plasma PG levels proved to be substantially higher in adapted animals than in the controls, but stress-induced plasma catecholamine release, i.e. stress reaction, showed a 2-3-fold decrease that in the controls undergoing the same stress. The findings along with the data on the cytoprotective and vasodilating action of PGE and PGI2 suggest that enhanced activity of the myocardial and blood PG system is the important link in the mechanism responsible for the antistress impact of adaptation.

Topics: Adaptation, Physiological; Altitude Sickness; Animals; Catecholamines; Dinoprost; Disease Models, Animal; Epoprostenol; Male; Myocardium; Prostaglandins E; Rats; Rats, Wistar; Restraint, Physical; Stress, Psychological; Thromboxane A2

Adrenergic cardiac and aortic lesion was reproduced by using intramuscularly a stress-necrogenic epinephrine dose of 2 mg/kg. Following 24 hours, the levels of malonic dialdehyde (MDA) as a TxA2 marker, were measured in the platelets. The antiaggregability of the aortic wall where PGI2 is synthesized was also examined. The adrenergic lesion was found to impair the platelet function-vascular wall balance, creating the condition for enhancing spontaneous platelet aggregation. This led to 50% death of experimental "lowland" rats. The short-term high-altitude adaptation failed to substantially modify the death rates in adrenergic lesion, though the platelets showed a 30% decrease in MDA generation. The combination of high-altitude adaptation and the calcium antagonist finoptin completely prevented the stress-induced increase in the platelet generation of MDA, a TxA2 marker, which was followed by a drastic reduction (16.6% versus 50%) in sudden death cases among the rats during adrenergic cardiac and aortic lesion.

Topics: Adaptation, Physiological; Altitude; Animals; Aorta, Abdominal; Disease Models, Animal; Epinephrine; Epoprostenol; Male; Myocardium; Necrosis; Platelet Aggregation; Rats; Thromboxane A2; Verapamil

Defibrotide (DEF), a compound previously found to stimulate vascular prostacyclin (PGI2) formation, has been investigated in an experimental model of septic shock. Anesthetized pigs were subjected to i.v. infusion of lipid A (1.5 mg/kg per hr for 4 hr). DEF (50 mg/kg per hr) or vehicle were infused i.v. throughout the experiments, starting 1 hr prior to lipid A. Two out of 7 pigs receiving vehicle survived lipid A infusion for 4 hr, whereas 6 out of 7 DEF treated animals survived this period (P less than 0.05). DEF delayed the shock-induced depression of platelet count and preserved platelet secretory function (collagen-induced ATP-secretion). DEF increased plasma PGI2 by 45% (P less than 0.05) during lipid A infusion and tended to reduce thromboxane levels. DEF did not change eicosanoid formation in sham-shock pigs (n = 4 per group). In vivo treatment with DEF significantly increased the stimulatory effect of bradykinin (1 microM) and arachidonic acid (100 microM) on PGI2 formation ex vivo of mesenteric and iliac artery segments. The improvement of survival in lipid A-induced shock by DEF may be related to an enhancement of vascular PGI2 generation, potentially due to a reduction of shock-induced platelet activation and microcirculatory dysfunction.

Topics: Animals; Arachidonic Acid; Blood Platelets; Bradykinin; Disease Models, Animal; Drug Synergism; Epoprostenol; Lipid A; Platelet Count; Polydeoxyribonucleotides; Shock; Survival Rate; Swine; Thromboxane A2

The effect of testosterone administration on plasma lipoproteins and eicosanoids was studied in 24 male cynomolgus monkeys. We hypothesized that elevated plasma testosterone would unfavorably alter plasma lipids as well as thromboxane A2 (TxA2) and prostacyclin (PGI2), two eicosanoids that have been linked to the increased incidence of atherosclerosis, myocardial ischemia, and thrombosis. To test our hypothesis, half of the monkeys (N = 12) were subjected to 10 wk of testosterone treatment, whereas the remaining monkeys (N = 12) received a sesame oil vehicle. The plasma concentrations of thromboxane B2 (TxB2) and 6-keto-PGF1 alpha, the stable metabolites of TxA2 and PGI2, respectively, were determined. Additionally, assays were conducted on total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), and triglycerides (TG). Distribution of the HDL subfraction protein was measured by gradient gel electrophoresis. All monkeys exhibited significant increases in TC (P less than 0.001) and low density lipoprotein cholesterol (LDL-C) (P less than 0.001); however, monkeys who received testosterone also displayed significant increases in TxB2 (P less than 0.03) and decreases in HDL-C (P less than 0.03) compared with control monkeys. There was a trend in the HDL-C subfraction data, indicating that testosterone treatment may be associated with a decrease in the larger HDL2b subfraction and a corresponding increase in HDL3c. These results demonstrate that exogenous testosterone adversely alters cardiovascular risk profiles by increasing TXB2 production and decreasing HDL-C. Athletes who use testosterone as an anabolic androgenic steroid may have an increased risk for coronary heart disease.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Cholesterol, HDL; Cholesterol, LDL; Coronary Disease; Disease Models, Animal; Eicosanoids; Epoprostenol; Lipids; Macaca fascicularis; Male; Testosterone; Thromboxane A2; Thromboxane B2

The pulmonary and systemic hemodynamic effects of recurrent endotoxemia were studied in pigs over a 48-hr period. Six pigs of the test group were given 0.5 micrograms/kg of an E. coli endotoxin (WO111: B4) over 60 min at the beginning and in the middle (22 hr) of the experiment. Three pigs given the same amount of physiological saline solution served as controls. The hemodynamic response to the first LPS injection was characterized by severe pulmonary hypertension, a significant increase in systemic vascular resistance, and a marked decrease in cardiac output. Circulating TxB2 levels were higher than those of 6-keto-PGF1 alpha levels, so that the first response to LPS is influenced by the vasoconstrictive actions of TxA2. With the second LPS application, the pulmonary response was attenuated, although a significant increase of pulmonary artery pressure and pulmonary vascular resistance occurred. Once again systemic vascular resistance rose and cardiac output decreased, but this time plasma levels of 6-keto-PGF1 alpha were greater than those of TxB2. Toward the end of the experiment, we noted the progressive onset of a hyperdynamic and hypotensive state. Systemic vascular resistant index decreased to 50% of the baseline value. IL-6, a cytokine of systemic importance during the course of septic shock, markedly and significantly peaked after each LPS injection. Circulating plasma levels in response to recurrent endotoxemia are described.

Topics: Animals; Disease Models, Animal; Endotoxins; Epoprostenol; Escherichia coli Infections; Hemodynamics; Interleukin-6; Shock, Septic; Swine; Thromboxane A2

To determine the role of thromboxane A2 in the pathogenesis of experimentally induced immune complex glomerulonephritis, 12 concanavalin A-immunized Beagles were infused with 1 mg of concanavalin A via each renal artery and treated twice daily for 8 days with either 30 mg of CGS 12970/kg, PO, a specific thromboxane synthetase inhibitor, or placebo. The effect of treatment was assessed by measuring endogenous creatinine clearance and urine protein and eicosanoid excretion, and by evaluating changes in glomerular morphometric characteristics. On postinfusion day 8, urine protein, thromboxane B2, and 11-dehydro-thromboxane B2 excretion, glomerular epithelial crescent formation, and glomerular cell proliferation in the CGS 12970-treated dogs were significantly decreased when compared with values in the placebo-treated group. Differences were not observed in endogenous creatinine clearance, urine prostaglandin E2 and 6-keto-prostaglandin F1 alpha excretion, or glomerular polymorphonuclear leukocyte infiltration between groups in this study. These findings suggest thromboxane A2 has a role in the development of immune complex glomerulonephritis and that thromboxane synthetase inhibition may be beneficial in attenuating some of the functional and histological changes associated with immune complex glomerulonephritis.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Concanavalin A; Dinoprostone; Disease Models, Animal; Dogs; Glomerular Filtration Rate; Glomerulonephritis; Immune Complex Diseases; Kidney; Kidney Glomerulus; Male; Pyridines; Thromboxane A2; Thromboxane B2; Thromboxane-A Synthase

Although (-)-(S)-trimetoquinol [1-(3,4,5-trimethoxy-benzyl)- 6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline; TMQ] is recognized as a potent bronchodilator, (+)-(R)-TMQ is a selective antagonist of human platelet aggregation and serotonin secretion induced by thromboxane A2 (TXA2) agonists. To confirm the pharmacological actions of TMQ analogs, the interaction of the drugs with TXA2 receptors was examined in human platelets and in a mouse sudden death model. The inhibitory potencies of TMQ analogs (pIC50 values) for displacement of [3H]SQ 29,548 binding to platelets showed excellent correlation with the respective pIC50 (-log IC50) values for U46619-induced aggregation (r = 0.99, P less than 0.01) and serotonin secretion (r = 0.99, P less than 0.01) in human platelet-rich plasma and for whole blood aggregation (r = 0.99, P less than 0.01). In each system, the rank order of inhibitory potencies was rac-iodoTMQ greater than or equal to (+)-(R)-TMQ greater than rac-TMQ much greater than (-)-(S)-TMQ. Antithrombotic effects of TMQ analogs were evaluated in a mouse sudden death model. In vivo antithrombotic potencies of these compounds were consistent with the in vitro potencies as TXA2 receptor antagonists in platelet systems. Administration of rac-iodoTMQ, (+)-(R)-TMQ and rac-TMQ 15 min before the injection of U46619 (800 micrograms/kg, iv) protected mice against U46619-induced sudden death. On the other hand, (-)-(S)-TMQ did not protect animals against death. Protection of U46619-induced cardiopulmonary thrombosis by TMQ analogs was seen at doses of 3-100 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Blood Platelets; Bridged Bicyclo Compounds, Heterocyclic; Death, Sudden; Disease Models, Animal; Fatty Acids, Unsaturated; Humans; Hydrazines; Male; Mice; Platelet Aggregation; Prostaglandin Endoperoxides, Synthetic; Receptors, Prostaglandin; Receptors, Thromboxane; Stereoisomerism; Thromboxane A2; Tretoquinol; Tritium

This study investigated the release of prostacyclin (PGI2) and thromboxane A2 (TXA2) from the aortic walls of various experimental hypertensive rats, e.g. spontaneously hypertensive rats (SHR), Dahl salt-sensitive (Dahl S) rats, deoxycorticosterone (DOCA)-salt hypertensive rats and renovascular (2-kidney, 1-clip (2K1C) and 1-kidney, 1-clip (1K1C] hypertensive rats. The PGI2 generation was increased significantly in these hypertensive models, irrespective of the hypertensive mechanisms, when they developed established hypertension. Dahl S rats, having an impaired PGI2 production on a low salt diet, restored PGI2 generating capacity to the control level of Dahl salt-resistant rats when they were fed a high salt diet and developed salt-induced hypertension. On the other hand, the TXA2 generation in the vascular walls was enhanced particularly in rat models for genetic hypertension, and this system was unaltered in the models for secondary hypertension, e.g. DOCA-salt and renovascular hypertension. Thus, it is suggested that the elevation of blood pressure is associated with an increase in vascular PGI2 production, and that the increased vascular TXA2 production is a characteristic feature of genetic hypertension.

Topics: Animals; Aorta; Blood Pressure; Blood Vessels; Disease Models, Animal; Eicosanoids; Epoprostenol; Hypertension; Hypertension, Renovascular; In Vitro Techniques; Male; Rats; Rats, Inbred SHR; Rats, Inbred Strains; Thromboxane A2; Tritium

The role of thromboxane A2 (TXA2) in myocardial necrosis during coronary occlusion and reperfusion was investigated by using a new long-acting TXA2 synthetase inhibitor, DP1904. A rabbit coronary branch was occluded for 30 min and then reperfused for 72h. Infarct size and area at risk were determined histologically and by fluorescent particles, respectively, for 4 groups; a saline receiving control group (C group), a DP1904 treated group (DP group), a heparin treated group (H group), and a DP1904 plus heparin treated group (DP-H group). The H group and DP-H group were included to examine the influence of heparinization on the effect of DP1904. In the DP and DP-H groups, 10 mg/kg of DP1904 was injected i.v. 2h before coronary occlusion, as well as 24 and 48h after reperfusion. This dose of DP1904 (10 mg/kg i.v.) was able to inhibit serum thromboxane B2 formation ex vivo to 1.1% of the control level 2h after its administration, and to 39.5% at 24h, in the rabbit (n = 5). The H and DP-H groups received 1000 units of heparin i.v. 3 min prior to coronary occlusion. The size of the area at risk, heart rate, blood pressure, and rate-pressure products were comparable between the 4 groups. Mortality was not significantly different in any group. Myocardial infarct size as the percentage of area at risk was 43.6 +/- 3.9% in C group (n = 10), 41.1 +/- 4.4% in DP group (n = 9), 47.8 +/- 3.0% in H group (n = 13), and 44.7 +/- 4.0% in DP-H group (n = 10), which were not significantly different. These findings suggest that TXA2 does not contribute directly to myocardial necrosis during coronary occlusion and reperfusion in the rabbit.

Topics: Animals; Constriction; Coronary Vessels; Disease Models, Animal; Heparin; Imidazoles; Male; Myocardial Infarction; Myocardial Reperfusion; Myocardium; Necrosis; Rabbits; Tetrahydronaphthalenes; Thromboxane A2; Thromboxane-A Synthase

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Disease Models, Animal; Epoprostenol; Free Radicals; Hepatic Artery; Ischemia; Lipid Peroxidation; Liver Circulation; Male; Prostaglandins; Rats; Rats, Inbred Strains; Reference Values; Thromboxane A2

To clarify the role of thromboxane (TX) A2 in arterial thrombus formation, we examined the antithrombotic effects of both a TXA2 synthetase inhibitor (CV-4151) and a TXA2 receptor antagonist (AA-2414) on the rabbit common carotid artery thrombosis which was induced by injury of the endothelium by treatment with 0.25% pronase solution. CV-4151 (1,10 mg/kg, p.o.) and AA-2414 (10 mg/kg, p.o.) significantly inhibited thrombus formation. Furthermore, the combined use of CV-4151 and AA-2414 (0.1 mg/kg, p.o. each) significantly inhibited thrombus formation, though these drugs at the same doses had no effect when administered singly. The plasma level of 11-dehydro TXB2 increased significantly during thrombus formation, and CV-4151 (10 mg/kg) markedly inhibited this increase. There was a significant correlation between the in vivo antithrombotic effects of these drugs and their ex vivo inhibitory effects on arachidonic acid-induced platelet aggregation. The antithrombotic effect of CV-4151 also correlated significantly with its ability to inhibit the production of serum TXA2. These results show that TXA2 may play an important role in the thrombus formation in arterial thrombosis.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Arachidonic Acid; Arachidonic Acids; Benzoquinones; Carotid Artery Thrombosis; Disease Models, Animal; Endothelium, Vascular; Fatty Acids, Monounsaturated; Heptanoic Acids; Male; Platelet Aggregation; Pyridines; Quinones; Rabbits; Thromboxane A2; Thromboxane B2; Thromboxane-A Synthase

The anti-helminthic drug levamisole has been used as an adjunct in the treatment of some immunologic defects including cancer. Recently, it has been shown that this drug inhibits thromboxane synthetase as well. Since Forssman shock in guinea pig is used as a model for pulmonary thromboembolism involving thromboxane A2, we studied the interference of levamisole with bronchoconstriction, thrombocytopenia, endothelial cells and pulmonary damage induced by Forssman antiserum. Levamisole inhibited dose-dependently the pathological changes produced by Forssman antiserum raising the possibility that levamisole may be effective for the treatment of pulmonary thromboembolism in man.

Topics: Animals; Antibodies; Disease Models, Animal; Endothelium, Vascular; Forssman Antigen; Guinea Pigs; Levamisole; Lung; Male; Platelet Count; Pressure; Pulmonary Embolism; Shock; Thromboxane A2

The effects of low dose indomethacin therapy in primary prevention of diet-induced atherosclerosis of rhesus monkeys was studied. The parameters studied were serum cholesterol concentration, thromboxane A2 (T x B2), prostacyclin (6-keto-PGF1 alpha) in serum/plasma, and the extent and intensity of coronary atherosclerosis. Although indomethacin did not affect serum cholesterol, it reduced serum T x B2 significantly (P less than 0.01). Plasma 6-keto-PGF1 alpha was not restored to the pretreatment level. A significant protective role of the drug was noted as far as coronary atherosclerosis is concerned (P less than 0.01).

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Body Weight; Cholesterol; Coronary Artery Disease; Diet, Atherogenic; Disease Models, Animal; Indomethacin; Macaca mulatta; Male; Thromboxane A2

We studied the inhibitory effects of OKY-046.HCl on PAF-induced airway hyperresponsiveness (AHR) in guinea pigs. 1) Inhalation of PAF (1 or 10 micrograms/ml) caused AHR to acetylcholine (ACh) aerosol and increased TXB2 generation in broncho-alveolar lavage fluid (BALF) at 30 min and 60 min, but the AHR and the TXB2 generation disappeared at 2 hr. OKY-046.HCl (100 mg/kg, intraduodenally) inhibited the AHR, which was accompanied by its inhibition of the TXB2 generation. However, no changes of 6-keto-PGF1 alpha in BALF were found. 2) There were no changes in the number of leukocytes; the activities of alkaline phosphatase, N-acetyl-beta-D-glucosaminidase, and lactate dehydrogenase; and the LTC4/D4/E4 in BALF. 3) In bronchus-lung preparations, PAF (1 microgram/min) also caused the AHR and increased TXB2 generation. OKY-046.HCl (100 micrograms/min) inhibited the AHR and TXB2 generation. 4) PAF (1 microgram/ml) evoked TXB2 generation in BALF from normal guinea pigs. OKY-046.HCl (10(-4)M) inhibited its increase. 5) Stable TXA2 (STA2, 1 ng/ml) inhalation also caused AHR to ACh at 30 min. STA2 (0.45 ng/min) also caused the AHR in bronchus-lung preparations. These results suggest that OKY-046.HCl can inhibit PAF-induced AHR by suppressing the generation of TXA2. We also supposed that TXA2 is released from lung parenchyma, airway epithelium and cell components in BALF.

Topics: Acrylates; Animals; Asthma; Bronchoalveolar Lavage Fluid; Disease Models, Animal; Guinea Pigs; In Vitro Techniques; Male; Methacrylates; Platelet Activating Factor; Thromboxane A2; Thromboxane-A Synthase

The early increase of pulmonary artery pressure observed in different models of experimentally induced lung injury have been shown to be associated with the release of vasoconstrictive agents by activated platelets. The aim of this study was to evaluate the pattern of these metabolites, in particular TxA2, and the effects of the inhibition of their production by ASA on the modifications of pulmonary hemodynamics induced by oleic acid administration in sheep. Group I (8 sheep) was infused with oleic acid (0.09 ml/kg at 0.02 ml/min) while in group II (6 sheep) ASA (10 mg/kg i.v.) was administered 30 minutes before oleic acid infusion. In group I pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR) were significantly higher at the end of the infusion while cardiac output (CO) significantly decreased in comparison to baseline values. A marked increase in plasma TxB2 levels paralleled pulmonary hemodynamic changes. Also plasma 6 keto PGF levels increased after OA infusion. The early increase in PAP and PVR was significantly lower in group II (p less than 0.005) while CO did not undergo any significant change. ASA pretreatment significantly blunted the rise of TxB2 concentrations and prevented the elevation of 6 keto PGFa. These results indicate that early pulmonary hypertension in oleic acid induced injury is mainly related to TxA2 released from platelets and leukocytes and that pulmonary hemodynamic changes are significantly inhibited by ASA pretreatment.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Aspirin; Blood Platelets; Blood Pressure; Disease Models, Animal; Hypertension, Pulmonary; Leukocytes; Oleic Acid; Oleic Acids; Sheep; Thromboxane A2; Vascular Resistance

To elucidate the possible involvement of thromboxane A2 (TxA2) in airway hyperresponsiveness, we examined the effect of OKY-046, a potent and selective inhibitor of TxA2 synthetase, on airway hyperresponsiveness induced by ozone exposure in dogs. Ozone exposure (3 ppm, 2 hr) markedly increased airway responsiveness to inhaled methacholine without affecting basal respiratory resistance. Although ozone also caused a slight but significant increase in neutrophil number in the bronchoalveolar lavage fluid, there was no correlation between the level of airway hyperresponsiveness and increased neutrophil number. Although OKY-046 significantly inhibited the increases in airway hyperresponsiveness in a dose-dependent manner at doses ranging from 100 to 300 mg/kg, p.o., the compound did not affect the basal airway responsiveness and respiratory resistance at 300 mg/kg, p.o. Inhalation of the subthreshold concentration (i.e., the highest dose which did not cause bronchoconstriction) of STA2 (a stable TxA2 mimetic agent) elicited a significant increase in airway responsiveness to methacholine. These results suggest that TxA2 may play a role in mediating ozone-induced airway hyperresponsiveness. However, the accumulation of neutrophils in the airway lumen may not be essential for the development of airway hyperresponsiveness.

Topics: Acrylates; Animals; Asthma; Disease Models, Animal; Dogs; Dose-Response Relationship, Drug; Female; Methacrylates; Ozone; Thromboxane A2; Thromboxane-A Synthase

We tested the hypothesis that prostaglandins (PGs) and thromboxane (Tx) A2 are important mediators of the hemodynamic derangements occurring in a rabbit model of hyperdynamic endotoxicosis. Rabbits were injected with either normal saline (NS) or Escherichia coli lipopolysaccharide (LPS; 1-3 micrograms/kg) and studied 6 hr later. Cardiac index (CI) and regional blood flow were determined using thermodilution and radioactive microspheres, respectively. Systemic and regional hemodynamics were determined before and 40 min after administering indomethacin (cyclo-oxygenase inhibitor; 5 mg/kg), UK38485 (Tx synthetase inhibitor; 10 mg/kg), or NS. LPS increased CI (P = .0024) and decreased mean arterial pressure (P = .0031) and systemic vascular resistance index (P = .0001). LPS increased flow to the heart and small intestine and decreased flow to the hepatic artery and pancreas. The systemic and regional hemodynamic effects of indomethacin were similar in NS- and LPS-treated rabbits. UK38485 decreased perfusion of skeletal muscle and diaphragm in both endotoxemic and control animals. This agent increased splenic perfusion only in NS-treated rabbits. Plasma levels of 6-keto PGF1 alpha (PGI2 metabolite) were typically undetectable in both NS- and LPS-treated rabbits. These data do not support the hypothesis that PG's or TxA2 are major determinants of the hemodynamic perturbations that occur in this endotoxicosis model.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Cyclooxygenase Inhibitors; Disease Models, Animal; Endotoxins; Escherichia coli; Hemodynamics; Imidazoles; Indomethacin; Lipopolysaccharides; Male; Prostaglandins; Rabbits; Shock, Septic; Thromboxane A2; Thromboxane-A Synthase

The method of infusion of hardened red blood cells described by Clement et al. (1983) to induce pulmonary hypertension in the minipig has been modified to obtain a model of pulmonary microembolism in the mouse. In this model, the infusion of hardened red blood cells causes the death of about 90% of control animals in 2-5 min, and the efficacy of a given pharmacological treatment can be assessed in terms of the percentage of animals protected from death 15 min after the infusion. Platelets are not apparently involved, since the number of circulating platelets, plasma levels of TxB2, and PF-4 are not modified, and the mortality in thrombocytopenic animals is not different from controls. Furthermore, aspirin and heparin are totally inactive in this model. Preliminary results with some Ca++ channel blockers (nitrendipine and nicardipine) indicate that these compounds may be active. This experimental model offers an easy and relatively inexpensive test for the characterization of compounds to prevent pulmonary microembolism, acting via a platelet-independent mechanism.

Topics: Animals; Disease Models, Animal; Erythrocytes; Fibrinolytic Agents; Mice; Platelet Count; Platelet Factor 4; Pulmonary Embolism; Thrombocytopenia; Thromboxane A2

Chronic sepsis was induced by administering endotoxin (lipopolysaccharide--LPS) at 12-hr intervals to sheep. The animals (n = 7) responded to the first dose of LPS with increased pulmonary arterial pressure (PAP), systemic vascular resistance, plasma and lymph thromboxane B2 (TxB2) concentrations, and lung lymph flow rate concurrent with a reduction in the cardiac index (CI). Subsequent doses of LPS produced an elevation of PAP and TxB2 which was progressively attenuated and eventually disappeared. With LPS the lung lymph flow was markedly elevated and CI increased. This latter was transient and associated with a reduction in systemic vascular resistance. Concomitant with the cardiopulmonary changes prekallikrein levels were not diminished, but there was a statistically significant reduction in C1-esterase inhibitor. The administration of LPS was discontinued after 5 days and the cardiopulmonary variables rapidly returned to baseline levels. Chronic endotoxemia appears to be associated with an elevated pulmonary microvascular permeability and a tendency toward a hyperdynamic circulation but with an appreciable degree of refractoriness associated with regional hemodynamics and eicosanoid biosynthesis.

Topics: Animals; Cardiac Output; Chronic Disease; Complement C1 Inactivator Proteins; Disease Models, Animal; Drug Administration Schedule; Endotoxins; Escherichia coli; Heart Rate; Hemodynamics; Hypertension, Pulmonary; Lipopolysaccharides; Lung; Lymph; Prekallikrein; Sheep; Shock, Septic; Thromboxane A2; Time Factors; Vascular Resistance

Splanchnic artery occlusion (SAO) followed by release of the occlusive clamps produces circulatory shock characterized by an abrupt hypotension, cardiac depression and high lethality. We studied the effects of the thromboxane receptor antagonist, BM-13505, in rats during SAO shock. Anesthetized rats subjected to total occlusion of the celiac and superior mesenteric arteries for 40 minutes developed a severe shock state following reperfusion, usually resulting in death within 90-120 minutes of release of the occlusion. BM-13505 was started at reperfusion for 10 minutes. SAO shock rats treated with BM-13505 (1 mg/kg) maintained post-reperfusion mean arterial blood pressure (MABP) at significantly higher values compared to those receiving only the vehicle (0.9% NaCl). Treatment with BM-13505 attenuated the plasma activity of the lysosomal protease cathepsin D (p less than 0.05 from vehicle) and the plasma accumulation of free amino-nitrogen compounds (p less than 0.01 from vehicle). Furthermore, the plasma activity of a myocardial depressant factor was significantly lower in BM-13505 treated rats than in non-treated rats (p less than 0.01 from vehicle). SAO shock rats treated with BM-13505 also exhibited a higher survival rate than the vehicle group (75% vs. 20%). These results suggest an important role of thromboxane A2 in the pathophysiology of SAO shock.

Topics: Animals; Blood Pressure; Cathepsin D; Disease Models, Animal; Hematocrit; Male; Mesenteric Vascular Occlusion; Myocardial Depressant Factor; Nitrogen; Phenylacetates; Rats; Rats, Inbred Strains; Shock; Splanchnic Circulation; Sulfonamides; Thromboxane A2

Topics: Animals; Blood Platelets; Collagen; Death, Sudden; Disease Models, Animal; Male; Platelet Activating Factor; Rabbits; Serotonin; Thromboxane A2

Topics: Animals; Disease Models, Animal; Dogs; Escherichia coli; Hemodynamics; Shock, Septic; Thromboxane A2

Tissue plasminogen activator and urokinase were evaluated in a model of prosthetic graft thrombosis. In addition, the effects of thrombus age on lysability and the effect of thrombolytic agents on endothelium were examined. Polytef (polytetrafluoroethylene [PTFE]) grafts (3 mm X 3.5 cm) were placed in femoral arteries of dogs and graft thrombosis was induced. Grafts were treated with a local infusion of either urokinase or tissue plasminogen activator (4000 units/min) and the times for initial flow, complete thrombolysis, and anastomotic bleeding were noted. The luminal surfaces of the grafts and the proximal arterial segments were assayed for the production of thromboxane A2 and prostacyclin and examined with scanning electron microscopy. No difference in the ease of graft lysis was observed, but 50% of tissue plasminogen activator-treated vs 0% of urokinase treated grafts had extravasation of blood through the wall. Grafts treated with tissue plasminogen activator produced less thromboxane A2 and had less thrombus than those treated with urokinase. No differences between arteries exposed to either agent and control arteries were seen. Grafts treated 1,3,5, and 7 days after thrombosis were progressively more difficult to lyse. We conclude that tissue plasminogen activator is an effective thrombolytic agent, but has a potential for local bleeding complications. Grafts of PTFE are thrombogenic after lysis, but may be less so with tissue plasminogen activator than with urokinase. No effect on arterial endothelium was seen, and our studies confirm the clinical impression that older thrombi are more difficult to lyse.

Topics: Animals; Arteries; Blood Vessel Prosthesis; Disease Models, Animal; Dogs; Epoprostenol; Graft Occlusion, Vascular; Hemorrhage; Microscopy, Electron, Scanning; Polytetrafluoroethylene; Thrombosis; Thromboxane A2; Time Factors; Tissue Plasminogen Activator; Urokinase-Type Plasminogen Activator

Topics: Animals; Coronary Vasospasm; Disease Models, Animal; Rabbits; Thromboxane A2

Topics: Animals; Arteriosclerosis; Coronary Vasospasm; Disease Models, Animal; Epoprostenol; Histamine; Indomethacin; Swine; Swine, Miniature; Thromboxane A2

U-63,557A, a new selective thromboxane synthetase inhibitor, was evaluated for its ability to prevent the extension of myocardial infarct size. Left coronary arteries of male Sprague-Dawley rats (230 - 270 g) were acutely ligated, producing a consistent model of myocardial infarction (MI) in rats analyzed 48 hours later. Left ventricular free wall (LVFW), creatine kinase (CK) activity, and amino-nitrogen concentrations were assayed as indices of infarct size. U-63,557A was administered intravenously in two doses (4 and 8 mg/kg) with a split schedule (2 min post-ischemia and either 4 or 24 hrs later). Administration of the thromboxane synthetase inhibitor significantly reduced both myocardial CK and amino-nitrogen loss at a dose of 8 mg/kg, but it was only slightly effective at 4 mg/kg. Drug treatment significantly increased the percent LVFW spared; 27 +/- 3% (vehicle) vs 43 +/- 7% and 52 +/- 7% (8 mg/kg). U-63,557A is an effective agent in myocardial ischemia for limiting the extension of infarct size after acute coronary artery ligation. Previous studies of other thromboxane synthetase inhibitors showed effectiveness in the early stages of MI. This study shows an effect on true infarct size 48 hours post-ligation, and suggests that inhibition of thromboxane A2 plays an important role in the pathogenesis of ischemic damage in the myocardium.

Topics: Animals; Benzofurans; Disease Models, Animal; Male; Myocardial Infarction; Oxidoreductases; Rats; Rats, Inbred Strains; Thromboxane A2; Thromboxane-A Synthase

The role of prostanoids in a swine model of coronary artery spasm was examined. Eighteen miniature pigs underwent endothelial denudation of the left coronary artery (left circumflex branch in 14 pigs and left anterior descending branch in 4 pigs) followed by high cholesterol feeding. Three months after the denudation, when coronary artery spasm was repeatedly provoked along the denuded portion of the coronary artery by histamine, the vasoconstrictive effect of thromboxane A2 and the preventive effects of indomethacin and prostacyclin against histamine-induced coronary artery spasm were examined. Intracoronary administration of thiothromboxane A2, 200 micrograms, a stable thromboxane A2 analog, failed to provoke coronary artery spasm (seven of seven cases) but nonselectively constricted the coronary artery by 33%. Intravenous administration of indomethacin, 2 mg/kg, or continuous intravenous infusion of prostacyclin, 50 ng/kg per min, failed to prevent histamine-induced coronary artery spasm (four of four and eight of eight cases, respectively), yet the spasm was all but prevented by intravenous pretreatment with diphenhydramine at a dose of 1 mg/kg. Thus, in this swine model, prostanoids may not play a primary role in the occurrence of coronary artery spasm.

Topics: Animals; Arteriosclerosis; Body Weight; Cholesterol; Coronary Vasospasm; Disease Models, Animal; Epoprostenol; Histamine; Indomethacin; Male; Prostaglandins; Swine; Swine, Miniature; Thromboxane A2

Isolated glomeruli, glomerular epithelial cells and mesangial cells contain the cyclooxygenase enzyme that converts arachidonic acid to prostaglandin (PG)-endoperoxides. Biologically active metabolites of the latter include PGE2, PGF2 alpha, PGI2 and Thromboxane (TX) A2. These substances modulate renal cortical functions, i.e. renin release, renal blood flow (RBF) and glomerular filtration rate. Acute glomerular injury (nephrotoxic serum nephritis) augments glomerular production of PGs and TXA2. Thromboxane A2 reduces glomerular function and inhibition of TXA2 synthesis preserves GFR and RBF in this disease model. Patients with chronic glomerulonephritis have a lower urinary excretion of 6-Keto-PGF1 alpha (the stable hydrolysis product of the vasodilator PGI2). In these patients, inhibition of PGI2 synthesis by a cyclooxygenase inhibitor leads to reductions in GFR and RBF inversely related to the basal urinary excretion of 6-Keto-PGF1 alpha. These findings suggest that in both acute and chronic glomerulonephritis, arachidonate metabolites may serve as pathophysiologic mediators of changes in glomerular function.

Topics: Acute Disease; Animals; Arachidonic Acids; Chronic Disease; Disease Models, Animal; Glomerulonephritis; Humans; Kidney Cortex; Kidney Glomerulus; Prostaglandins; Thromboxane A2

Perinatal cerebral infarction is a not uncommon finding in newborn babies surviving intensive care. Asphyxia, with its attendant hypotension, is the most common cause of this problem and may result in neuropathological changes in the periventricular white matter. Previous studies have demonstrated uncoupling of cerebral blood flow and metabolism in the periventricular white matter regions of newborn beagle pups exposed to hemorrhagic hypotension. This work examines the effects of hypotension on serum and regional cerebral prostaglandin levels in the newborn beagle pup. The animals were anesthetized, tracheostomized, and paralyzed. Pups were randomly assigned to two groups: one was subjected to hemorrhagic hypotension and the other received no insult. Hypotension was induced by slow venous hemorrhage calculated to maintain a mean arterial blood pressure at 20 to 30 mm Hg. Serum prostaglandin determinations were made immediately before and 15 minutes after random assignment to hypotension or control groups. In addition, regional cerebral prostaglandin determinations were performed 15 minutes after randomization. Analysis of the serum prostaglandin data revealed that there were no significant differences in the values for thromboxane B2 or 6-keto-prostaglandin (PG) F1 alpha, which are the stable breakdown products of thromboxane A2 and prostacyclin, respectively. Prostaglandin E2 levels increased in response to hemorrhagic hypotension insult. Regional cerebral prostaglandin determinations demonstrated decreases in thromboxane B2 and 6-keto-PGF1 alpha in both gray and white matter. Although gray matter PGE2 was increased in pups exposed to hemorrhagic hypotension, this increase was not found in the periventricular white matter of injured pups. This regional difference in PGE2 synthesis in response to insult may explain the periventricular white matter neuropathological changes attributed to it.

Topics: Animals; Animals, Newborn; Cerebral Hemorrhage; Cerebral Infarction; Cerebrovascular Circulation; Disease Models, Animal; Dogs; Hypotension; Prostaglandins; Prostaglandins E; Thromboxane A2; Thromboxane B2

Prostacyclin, or prostaglandin I2 (PGI2), and thromboxane A2 (TXA2) are potent, endogenously produced, vasoactive substances that have been implicated as mediators in the pathophysiologic nature of septic shock. We investigated the contribution and production of PGI2 and TXA2 in sepsis and septic shock, using an intact rabbit model and an in vitro rabbit isolated cardiac perfusion model. Continuous hemodynamic monitoring of both experimental models, along with serial radioimmunoassays of the metabolites of PGI2 and TXA2, indicated that myocardial depression is a common finding in subjects with septic shock and that septic shock causes a suppression of PGI2 production while augmenting TXA2 production. In addition, PGI2 and TXA2 were mediators of some cardiovascular changes in septic shock but were themselves not the toxic factor(s) responsible for the associated myocardial depression.

Topics: Animals; Bacterial Infections; Disease Models, Animal; Epoprostenol; Heart; Hemodynamics; Humans; Hypotension; Myocardial Contraction; Rabbits; Shock, Septic; Thromboxane A2; Thromboxanes

This study investigates the role of prostaglandins (PG) in hyperdynamic sepsis. Thirteen chronically instrumented dogs were rendered septic by implanting in the peritoneal cavity a fibrin clot containing viable Escherichia coli. One day later, cardiac output (CO) increased from 2.80 +/- 0.22 to 3.72 +/- 0.32 l/min (p = 0.011); heart rate (HR) increased from 122 +/- 8 to 147 +/- 6 beats/min (p = 0.005); mean pulmonary artery pressure (PAP) increased from 15 +/- 1 to 19 +/- 1 mmHg (p = 0.003); mean systemic arterial pressure (MAP) decreased from 120 +/- 5 to 107 +/- 7 mmHg; and systemic vascular resistance (SVR) decreased from 44.1 +/- 2.6 to 29.3 +/- 1.9 mmHg/l/min (p less than 0.001). Sixty minutes after intravenous injection of indomethacin (2 mg/kg) or ibuprofen (25 mg/kg), CO decreased to 2.60 +/- 0.21 l/min (p less than 0.001); HR decreased to 118 +/- 5 beats/min (p less than 0.001); PAP decreased to 17 +/- 1 mmHg (p = 0.021); and SVR increased to 43.7 mmHg/l/min (p less than 0.001). In seven control dogs, laparotomy alone did not significantly affect any of these parameters. Infusion of indomethacin caused a slight increase in MAP (106 +/- 4 to 116 +/- 4 mmHg, p = 0.035) but otherwise did not alter hemodynamics. It is concluded that administration of indomethacin or ibuprofen restores normal hemodynamics in a canine model of high-output sepsis, probably by inhibiting PG synthesis.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Disease Models, Animal; Dogs; Escherichia coli Infections; Female; Hemodynamics; Ibuprofen; Indomethacin; Male; Oxygen Consumption; Peritonitis; Prostaglandin Antagonists; Prostaglandins; Sepsis; Shock, Septic; Thromboxane A2

Unilateral ureter obstruction in rabbits produced profound changes in endogenous and exogenous renal arachidonic acid metabolism. Isolated perfused hydronephrotic kidneys (removed after 3 or 10 d of ureter obstruction) responded to bradykinin stimulation with a markedly enhanced release of prostaglandin E2 and thromboxane A2. Reversal (3 or 10 d) of the ureter obstruction resulted in a reduction in the vasoactive peptide-induced release of prostaglandin E2 and thromboxane A2 from the perfused hydronephrotic kidney. However, postobstruction reversal of prostaglandin production by the agonist-stimulated perfused kidney was not reflected in the cortical microsomal cyclooxygenase activity, which is greatly enhanced during ureter obstruction and does not decrease after removal of the obstruction. Histological analysis of the renal cortex in rabbits with ureteral obstruction revealed a proliferation of fibroblast-like cells and the presence of mononuclear cells; removal of the obstruction did not result in a disappearance of cortical fibroblasts but did result in a decrease of monocytes. The critical involvement of mononuclear cells in the exaggerated arachidonate metabolism that occurs during hydronephrosis was exhibited by the demonstration that: (a) only the perfused hydronephrotic rabbit kidney responded to administration of endotoxin with a sustained release of prostaglandin E2 and thromboxane A2; (b) the contralateral rabbit kidney, which is devoid of mononuclear cells, did not respond to endotoxin; and (c) the hydronephrotic cat kidney, which exhibits a fibroblast proliferation with a low number of mononuclear cells, did not respond to endotoxin. Thus, proliferation of fibroblast-like cells and the presence of mononuclear cells appear to be involved in the exaggerated prostaglandin and thromboxane production underlying hydronephrosis. The increase in microsomal cyclooxygenase activity is apparently most closely correlated with the increased fibroblastic activation and cellularity, whereas mononuclear cells (possibly via monokines) seem to be critical for the markedly enhanced prostaglandin and thromboxane release induced by endotoxin and bradykinin.

Topics: Animals; Arachidonic Acids; Bradykinin; Cats; Disease Models, Animal; Endotoxins; Fibroblasts; Inflammation; Microsomes; Monocytes; Prostaglandins E; Rabbits; Thromboxane A2; Thromboxanes; Ureteral Obstruction

Topics: Adenosine Diphosphate; Animals; Blood Platelets; Blood Vessels; Coronary Disease; Diet; Disease Models, Animal; Endothelium; Fatty Acids; Humans; Hyperlipoproteinemia Type II; Lipids; Lipoproteins, HDL; Lipoproteins, LDL; Thrombosis; Thromboxane A2