thromboxane-a2 and nafagrel

To examine abnormalities of prostanoid metabolism in lupus nephritis, which may affect renal function, and the effects of 4 day dosing of a selective thromboxane A2 (TXA2) synthetase inhibitor, DP-1904, on prostanoid metabolism.. Urinary levels of various prostanoids, thromboxane B2(TXB2), 11-dehydro-TXB2, 6-keto-prostaglandin F1 alpha, 2,3-dinor-6-keto-PGF1 alpha, and prostaglandin E2 were determined. In a randomized crossover study, 8 patients with biopsy proven lupus nephritis were given 4 days' oral administration of DP-1904 (400 mg/day bid) or indomethacin (50 mg/day bid). The effects of DP-1904 on prostanoid metabolism were studied.. Urinary excretion of TXB2, which reflects the renal production of TXA2, was significantly increased in patients with lupus nephritis compared with non-renal systemic lupus erythematosus (SLE)(p < 0.05); enhanced production of TXA2 was also estimated in patients with lupus nephritis. The urinary TXB2/6-keto-PGF1 alpha ratio was also increased in lupus nephritis compared with non-renal SLE (p < 0.01), indicating a prostanoid imbalance that may lead to impaired renal function and subsequent pathology. During administration of DP-1904, the urinary excretion of TXB2 was significantly decreased after 1 to 2 days. An increase in creatinine clearance as a measure of renal function was observed. In contrast, during the administration of indomethacin, urinary excretion of both TXB2 and 6-keto-PGF1 alpha decreased and there were no significant changes in the urinary TXB2/6-keto-PGF1 alpha ratio or creatinine clearance. Hemodynamic changes were associated with a slight increase in sodium excretion, but with no change in arterial blood pressure. No side effects were elicited during the 4 days of treatments.. The abnormal prostanoid metabolism observed in lupus nephritis could aggravate renal function, which was mediated hemodynamically, and the altered metabolism was reversible and at least partially corrected by a TXA2 synthetase inhibitor, DP-1904.

Topics: Adult; Enzyme Inhibitors; Female; Humans; Imidazoles; Indomethacin; Kidney; Lupus Nephritis; Middle Aged; Prostaglandins; Tetrahydronaphthalenes; Thromboxane A2; Thromboxane-A Synthase

To examine the role of immune complexes in the prostanoid metabolism of glomerular capillary endothelial cells (EC) and platelets in lupus nephritis. Heat aggregated IgG (HA-IgG), instead of immune complexes, was incubated using an in vitro coculture system with human umbilical vein EC, instead of glomerular capillary EC, and platelets. The effect of complement component C1q and a novel imidazole-type thromboxane A2 (TXA2) synthetase inhibitor, DP-1904, on this prostanoid metabolism change was also investigated.. EC monolayers (1.5x10(5) cells/well) were incubated with various concentrations of HA-IgG, monomeric IgG, or medium alone for 1 h at 37 degrees C, and then incubated with platelet suspensions (1x10(8) cells/ml) for various times. Concentrations of TXB2 and 6-keto-prostaglandin F(1alpha) (6-keto-PGF(1alpha)), the stable hydrolysis products of TXA2 and prostaglandin I2 (PGI2), respectively, released in the supernatants were measured by ELISA.. HA-IgG bound to EC monolayers produced TXB2 and 6-keto-PGF(1alpha) in a concentration dependent manner and much more than monomeric IgG or medium alone did. However, the production of 6-keto-PGF(1alpha) stimulated with HA-IgG was much lower than that of TXB2, indicating a large imbalance between TXA2 and PGI2. Preincubation of HA-IgG with purified C1q partially suppressed the production of TXB2, but not that of 6-keto-PGF(1alpha). DP-1904 suppressed the production of TXB2 completely, but by sharp contrast, it dramatically increased the production of 6-keto-PGF(1alpha) from EC and platelets by HA-IgG.. The large imbalance of TXA2 and PGI2 produced by the interaction of EC, immune complexes, and platelets may be associated with alterations in glomerular pathological findings and hemodynamics mediated by immune complexes in lupus nephritis. C1q and a TXA2 synthetase inhibitor may improve the abnormal prostanoid metabolism change of lupus nephritis.

Topics: Antigen-Antibody Complex; Blood Platelets; Cells, Cultured; Coculture Techniques; Complement C1q; Endothelium, Vascular; Epoprostenol; Hot Temperature; Humans; Imidazoles; Immunoglobulin G; Infant, Newborn; Lupus Nephritis; Male; Tetrahydronaphthalenes; Thromboxane A2; Thromboxane-A Synthase

Recently, it has been demonstrated that the production of prostaglandins and thromboxane is increased in patients with chronic glomerulonephritis and lupus nephritis. We recently demonstrated that thromboxane A(2) delayed the clearance of heat-aggregated bovine serum albumin deposited in glomeruli. In the present study, we investigated the effect of thromboxane A(2) on the clearance of macromolecules in nephritic glomeruli. First, we attempted to clarify the conditions for the clearance of heat-aggregated bovine serum albumin in nephritic glomeruli, using glomeruli isolated from control and anti-glomerular basement membrane nephritic mice. Heat-aggregated bovine serum albumin was injected twice into each mouse. The glomeruli were then isolated and incubated in culture medium. The heat-aggregated bovine serum albumin content of control glomeruli gradually diminished with incubation time up to 24 h. The heat-aggregated bovine serum albumin content of nephritic glomeruli was 69% higher than that of control glomeruli at 24 h incubation. The production of thromboxane B(2) (the stable metabolite of thromboxane A(2)) in nephritic glomeruli showed about a sevenfold increase compared with control. DP-1904 [6-(1-imidazolylmethyl)-5,6,7,8-tetrahydro-naphthalene-2-carboxylic acid hydrochloride], a thromboxane A(2) synthase inhibitor, and KT2-962 [sodium 3-(4-(4-chlorophenyl-butylsulfonamido) butyl)-6-isopropylazulene-1-sulfonate], a selective thromboxane A(2) receptor antagonist, significantly reduced the heat-aggregated bovine serum albumin content in nephritic glomeruli. Normal glomeruli treated with U-46619 [15S-hydroxy-11a,9a-(epoxymethano)prosta-5Z,13E-dienoic acid], a stable analogue of thromboxane A(2), had significantly more heat-aggregated bovine serum albumin than control glomeruli. We next investigated whether thromboxane A(2) could affect the uptake/disposal of heat-aggregated bovine serum albumin by cultured rat mesangial cells. U-46619 significantly enhanced the uptake and inhibited the disposal of heat-aggregated bovine serum albumin by mesangial cells. Finally, we performed experiments to elucidate the role of the thromboxane A(2) receptor (TP receptor) in the clearance of heat-aggregated bovine serum albumin using TP-deficient mice. The glomerular heat-aggregated bovine serum albumin content of TP-receptor knockout [TP(-/-)] mice was lower than that of wild-type [WT(+/+)] mice. U-46619 dose dependently increased the uptake of heat-aggregated bovine s

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Antibodies; Autoantibodies; Benzenesulfonates; Cells, Cultured; Cycloheptanes; Enzyme Inhibitors; Glomerular Mesangium; Hot Temperature; Imidazoles; Kidney Glomerulus; Lupus Nephritis; Male; Mice; Mice, Inbred ICR; Mice, Knockout; Nephritis; Receptors, Thromboxane; Serum Albumin, Bovine; Tetrahydronaphthalenes; Thromboxane A2; Thromboxane-A Synthase; Vasoconstrictor Agents

An augmented contraction and elevated thromboxane (TX) B2 release were observed, when the isolated parenchyma from Sephadex-treated rats was stimulated by 5-hydroxytryptamine (5-HT). Release of peptide leukotrienes (pLTs) was also increased by the stimuli. In the Sephadex-induced hyperresponsiveness model, DP-1904, a novel TX synthetase inhibitor, at the concentrations of 3 x 10(-7) to approximately 3 x 10(-6) M, reduced the augmented contraction. Also, indomethacin (3 x 10(-6) M), a histamine H1 antagonist and AA-2414 (10(-6) M, a TXA2 antagonist, significantly attenuated the hyperresponsiveness to 5-HT. ICI-198,615 (10(-7) M), a leukotriene receptor antagonist, partially but significantly reduced the augmented contraction. In an ex vivo study, oral DP-1904 significantly inhibited both the augmented contraction and elevated TXB2 release from Sephadex-treated rat parenchyma, but did not affect the blood eosinophilia induced by Sephadex-treatment. These results suggested that the ability to synthesize newly generated lipid mediators such as TXA2 and pLTs to exogenous 5-HT was altered upward by Sephadex injection, and so could lead to augmented contraction of established hyperresponsiveness in rats.

Topics: Animals; Anti-Asthmatic Agents; Benzoquinones; Dextrans; Dose-Response Relationship, Drug; Enzyme Inhibitors; Eosinophils; Heptanoic Acids; Imidazoles; Indazoles; Indomethacin; Leukotrienes; Lung; Male; Organ Culture Techniques; Rats; Rats, Sprague-Dawley; Serotonin; Tetrahydronaphthalenes; Thromboxane A2

A marked and sustained bronchoconstriction after antigen challenge was produced in actively sensitised guinea pigs, and correlated with increments of thromboxane (TX) A2 level in both the plasma and bronchoalveolar lavage fluid. DP-1904 given orally relieved the bronchoconstriction and increase in TXA2 in a dose-dependent manner. In platelet-depleted animals, antigen-induced bronchoconstriction and TXA2 release in the plasma were significantly reduced compared to those of non-platelet-depleted animals, indicating that platelets are a major cell source of TXA2 production, the remainder originating from the other cells excluding platelets. In the platelet-deprived animal, DP-1904 showed further significant inhibition of the constriction and plasma TXA2 level, and therefore likely inhibits TXA2 synthesis of various cells, including platelets, in the bloodstream. The results suggested that TXA2 is an important mediator responsible for producing antigen-induced bronchoconstriction, and endogenously originated from various cells including platelets in guinea pigs.

Topics: Animals; Anti-Asthmatic Agents; Antigens; Asthma; Blood Platelets; Enzyme Inhibitors; Guinea Pigs; Imidazoles; Male; Tetrahydronaphthalenes; Thromboxane A2; Thromboxane B2; Thromboxane-A Synthase

The contractile activity and mobilisation of arachidonic acid metabolites in response to the antigen challenge were studied in isolated lung parenchymal tissue from the actively sensitised guinea pig. The sustained constriction of the lung tissue was evoked by the antigen, associated with significant liberation of TXB2, histamine and p-LTs. Other prostanoids (PGF2 alpha, PGD2, PGE2 and 6-keto-PGF1 alpha) were also released by the antigen challenge. DP-1904, an inhibitor of TX synthetase, significantly suppressed the late phase of the antigen-induced constriction. DP-1904 was potent to inhibit the production of TXB2, while DP-1904 accelerated the formation of PGF2 alpha, PGE2 and 6-keto-PGF1 alpha, presumably indicating the alternative changes of dilatory metabolites to the spasmogenic component. Mepyramine and FPL-77512 augmented the effect of DP-1904. AA-861 inhibited the antigen-induced constriction of the lung parenchymal tissue by inhibiting the release of p-LTs and TXB2. Pretreatment of the lung parenchymes with anti-guinea pig platelet serum, in order to deplete the platelets, did not affect the generation of TXB2 both in resting and also in the antigen-stimulated status, indicating that TXA2 is produced in the topical pulmonary tissue. It is concluded that DP-1904 inhibits the parenchymal contraction through potent inhibition of TXA2 generation, associated with significant elevation in PGE2 and PGI2.

Topics: Animals; Anti-Asthmatic Agents; Antigens; Benzoquinones; Bronchoconstriction; Chromones; Enzyme Inhibitors; Guinea Pigs; Imidazoles; In Vitro Techniques; Lipoxygenase Inhibitors; Lung; Male; Pyrilamine; Tetrahydronaphthalenes; Thromboxane A2; Thromboxane B2; Thromboxane-A Synthase

The effect of DP-1904, a novel thromboxane (TX) synthetase inhibitor, on airway hyperresponsiveness was studied in actively sensitized guinea-pigs. Airway hyperresponsiveness to intravenous ACh was observed at 3 and 7 h after aerosolized antigen challenge. In the model, a significant correlation between increases of respiratory resistance and microvascular leakage was observed, corresponding to the elevation of TXB2 in bronchoalveolar lavage fluid (BALF) in the early phase. DP-1904, at doses of 3 mg/kg or higher given orally one hour prior to the antigen challenge, inhibited the TXB2 production and the development of airway hyperresponsiveness in the early phase. Further, DP-1904 significantly suppressed the accumulation of lymphocytes in BALF and airway hyperresponsiveness in the late phase, although it only slightly decreased the mobilization of eosinophils and neutrophils. The results suggest that TXA2 is possibly involved in the development of airway hyperresponsiveness, and DP-1904 prevented the airway hyperresponsiveness via inhibition of TXA2 production and regulation of inflammatory cells.

Topics: Acetylcholine; Animals; Bronchoalveolar Lavage; Dinoprostone; Dose-Response Relationship, Drug; Enzyme Inhibitors; Guinea Pigs; Imidazoles; Lymphocytes; Male; Respiratory Hypersensitivity; Tetrahydronaphthalenes; Thromboxane A2; Thromboxane B2; Thromboxane-A Synthase; Time Factors

The chemoattractant f-Met-Leu-Phe (FMLP) can modulate human coronary arterial tone without the involvement of peripheral leukocytes. We investigated the actions of FMLP and its cellular mechanism in human coronary arteries isolated 2-3 h after death. A single dose of FMLP (0.01-10 microM) produced transient contraction (or, followed by relaxation) responses in most human coronary rings examined. These responses to FMLP were in large part mediated by the generation of cyclooxygenase products, mainly thromboxane A2 (TXA2) and prostaglandin I2 (PGI2). Radiolabeled N-formyl hexapeptide. 125I-f-Nle-Leu-Phe-Nle-Tyr-Lys bound densely to intimal and adventitial sites that accumulated macrophages (CD68-positive) with a Kd of 14-29 nM and, further, weakly to the media with a Kd of 2.4-3.6 microM. Several cell types including macrophages, endothelial cells and smooth muscle cells were positively immunostained for both TXA2 synthase and PGI2 synthase. However, there was no significant relation between the magnitude of the responses to FMLP and dense macrophage accumulation in the intimal plaques or the adventitia. A reverse transcription-polymerase chain reaction showed predominant expression of FMLP receptor homologues, FPRH1 and FPRH2 mRNA, in human coronary medial tissues relative to that in leukocytes. In conclusion. FMLP produced transient tension changes in human coronary arteries, mainly via the generation of TXA2 and PGI2. This effect of FMLP did not appear to be mediated by the activation of densely accumulated intimal and/or adventitial macrophages, but by the activation of unidentified medial tissue cells which might have functional FMLP receptor homologues.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Coronary Vessels; Cyclooxygenase Inhibitors; Cytochrome P-450 Enzyme System; Endothelium, Vascular; Enzyme Inhibitors; Female; Humans; Imidazoles; Indomethacin; Intramolecular Oxidoreductases; Isomerases; Isometric Contraction; Macrophages; Male; Middle Aged; N-Formylmethionine Leucyl-Phenylalanine; Oligopeptides; Prostaglandins; Receptors, Formyl Peptide; Receptors, Immunologic; Receptors, Peptide; RNA, Messenger; Tetrahydronaphthalenes; Thromboxane A2; Thromboxane-A Synthase

Antigen-stimulated contraction and release of chemical mediators were examined in saline- or Sephadex-treated rat lung parenchymal strips. Sephadex treatment caused eosinophilia in the blood and the lung tissue. Antigen challenge of the isolated parenchymal strips in Sephadex-treated rat was followed by passive sensitization, resulted in an augmented contraction and elevated releases of thromboxane (TX) B2 and peptide-leukotrienes (p-LTs) in bath fluid compared with those of saline-treated control. Although 5-hydroxytryptamine (5-HT) and histamine were significantly released after antigen challenge, the levels were not different between saline- and Sephadex-treated groups. DP-1904, a selective thromboxane synthetase inhibitor, and methysergide but not atropine significantly reduced the augmented contraction and inhibited the elevated TXB2 release in the Sephadex-treated group. Similar increased contraction and the elevated TXB2 release above were observed when Sephadex-treated rat lung strips were stimulated by exogenous 5-HT and LTD4. These augmented contractions were closely correlated with the increase in TXB2 level (r = 0.83; p < 0.01). In addition, contraction to U-46619, a thromboxane mimetic, was significantly greater in Sephadex-treated rat lung strips. Our results indicate that the ability of Sephadex-treated rat lung tissue to synthesize newly generated mediators such as TXA2 and p-LTs is increased, and the spasmogenic susceptibility of the lung tissue to TXA2 itself is modified by Sephadex treatment, suggesting these are due to the augmented contraction in an established hyperresponsiveness state induced by Sephadex.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Atropine; Bronchial Hyperreactivity; Dextrans; Dose-Response Relationship, Drug; Imidazoles; Leukotriene D4; Lung; Male; Methysergide; Prostaglandin Endoperoxides, Synthetic; Pulmonary Eosinophilia; Rats; Rats, Sprague-Dawley; Tetrahydronaphthalenes; Thromboxane A2; Vasoconstrictor Agents

Intercellular adhesion molecule-1 (ICAM-1) is an antigen that is strongly expressed by vascular endothelial cells at sites of local inflammation and participates in the development of inflammation. In the present study, vascular endothelial cells were stimulated by inflammatory cytokines that promote thromboxane A2 synthesis to observe their effects on the expression and shedding of ICAM-1 on the cell surface. In addition, the suppressive effects of DP-1904 ([+/-]-6-[1-imidazolylmethyl]-5,6,7,8-tetrahydronaphthalene-2- carboxylic acid hydrochloride hemihydrate), a thromboxane A2 synthesis inhibitor, on ICAM-1 expression were evaluated. ICAM-1 expression on the surface of human umbilical vein endothelial cells was increased significantly by stimulation with interleukin-1 beta, tumor necrosis factor alpha (TNF alpha), thrombin and platelet-activating factor (PAF). DP-1904, an inhibitor of thromboxane A2 synthesis, significantly suppressed the expression of ICAM-1 on the surface of human vascular endothelial cells that had been stimulated by TNF alpha or PAF. These findings suggest that an enhanced expression of thromboxane A2 on human vascular endothelial cells is closely related to the expression of ICAM-1 on the surface of these cells.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Cell Division; Cells, Cultured; Cycloheximide; Endothelium, Vascular; Epoprostenol; Fluorescein-5-isothiocyanate; Fluorescent Antibody Technique; Humans; Imidazoles; Intercellular Adhesion Molecule-1; Interleukin-1; Platelet Activating Factor; Prostaglandin Endoperoxides, Synthetic; Recombinant Proteins; Tetrahydronaphthalenes; Thrombin; Thromboxane A2; Thromboxane-A Synthase; Tumor Necrosis Factor-alpha; Umbilical Veins

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

The effects of DP-1904, a thromboxane (TX) A2 synthase inhibitor, on renal function were investigated by analysis of prostanoid metabolism in hydronephrotic and ischemic rat kidney models, and in isolated perfused normal and hydronephrotic rat kidneys. The increase in production of TXB2 in hydronephrotic or ischemic kidneys was significantly suppressed by intraperitoneal DP-1904 (10 mg/kg), with the 6-keto-prostaglandin F1 alpha to TXB2 ratio being significant increased. Urine volume, glomerular filtration rate and renal plasma flow were all improved. DP-1904 (0.3 micrograms/min) blocked the effects of infused arachidonic acid on isolated perfused normal rat kidneys thus reducing TXB2 levels and perfusion pressure but the pressor response to norepinephrine or angiotensin II remained unchanged. In isolated perfused hydronephrotic rat kidneys, DP-1904 suppressed the increase in perfusion pressure and TXB2 production caused by platelet-activating factor. These findings suggested that DP-1904 improved renal failure by specifically inhibiting TXA2 production.

Topics: 6-Ketoprostaglandin F1 alpha; Acute Kidney Injury; Animals; Hydronephrosis; Imidazoles; Ischemia; Kidney; Male; Perfusion; Rats; Rats, Inbred Strains; Tetrahydronaphthalenes; Thromboxane A2; Thromboxane B2; Thromboxane-A Synthase

Thromboxane A2 (TxA2) is a potent platelet aggregator as well as a vascular and bronchial constrictor. DP-1904, a newly synthesized imidazol TxA2 synthetase inhibitor, is a potent and long-acting agent. The present investigation was conducted to explore the effect of DP-1904 on the contractile responses in rabbit pulmonary artery and descending aorta strips induced by various vasoactive substances. Fourteen Japanese albino rabbits, weighing about 3 kg, were sacrificed. Rabbit pulmonary artery and descending aorta were removed, cut spirally, set up in bioassay glass jackets and superfused with Krebs-Henseleit solution at 37 degrees C, saturated with oxygen and carbon dioxide. Contraction of tissues was detected by an isotonic transducer and displayed on a polyrecorder. Arachidonic acid-induced contractile responses in rabbit pulmonary artery and descending aorta strips were attenuated significantly by the continuous infusion of DP-1904 in a dose-dependent fashion. Prostaglandin F2 alpha-induced contractile responses in rabbit pulmonary artery and descending aorta strips were attenuated significantly by the continuous infusion of DP-1904, dose-dependently. Angiotensin II-induced contractile responses in rabbit pulmonary artery and descending aorta strips were attenuated significantly by the continuous infusion of DP-1904, dose-dependently. Norepinephrine-induced contractile responses in rabbit pulmonary artery and descending aorta strips were attenuated significantly by the continuous infusion of DP-1904, dose-dependently. The above results suggest that DP-1904 might be a useful therapeutic agent for treatment of pulmonary hypertension in patients with chronic obstructive lung diseases.

Topics: Animals; Aorta, Thoracic; Chemical Phenomena; Chemistry; Dose-Response Relationship, Drug; Imidazoles; In Vitro Techniques; Muscle Contraction; Muscle, Smooth, Vascular; Naphthalenes; Pulmonary Artery; Rabbits; Tetrahydronaphthalenes; Thromboxane A2; Thromboxane-A Synthase; Vasoconstrictor Agents