Aspirin is essential in secondary prevention of patients after myocardial infarction and with coronary artery disease. However, impaired pharmacodynamic response to aspirin is frequent (high on-treatment platelet reactivity [HTPR]). This leads to an enhanced prevalence of cardiovascular events and to an impaired clinical outcome. The current specific assays to evaluate aspirin antiplatelet effects are complex, time-consuming and demand for a high laboratory expertise. Therefore, we developed a potentially bedside assay based on the determination of malondialdehyde (MDA). MDA is a by-product of the thromboxane (TX) formation, which is synthesized in equimolar concentrations. In this study, we compared this MDA assay to the conventional assays in determination of pharmacodynamic aspirin response. For this, aspirin antiplatelet effects were measured in 22 healthy individuals and 63 aspirin treated patients using TX B2 formation enzyme-linked antibody assay, arachidonic acid induced light transmission aggregometry (LTA) and the new fluorometric MDA assay. In patients, MDA levels correlated well with TX formation (R = 0.81; 95% CI 0.69-0.88; p < 0.001) and LTA (R = 0.84; CI 0.74-0.91; p < 0.001). Receiver operating characteristic analyses revealed that the MDA assay does detect HTPR to aspirin sufficiently (area under the curve: 0.965; p < 0.001). The optimal cut-off was>> 128 nmol/L (sensitivity of 100%, specificity of 91%). The new MDA assay is reliable in detecting HTPR. It is highly specific in the evaluation of antiplatelet effects by aspirin. This promising and potential bedside assay needs to be evaluated in clinical practice.

Phenylbutazone was administered intravenously and orally to six goats as a single dose of 4.4 mg/kg and its disposition and bioavailability and the disposition of its active metabolite, oxyphenbutazone, in plasma were investigated. The effect of the administration of the drug of oxyphenbutazone on ex vivo serum thromboxane (TX)B2 generation in platelets was also studied. Phenylbutazone was eliminated slowly with mean (se) elimination half-lives (t1/2 beta) of 15.3 (1.15) hours and 22.0 (3.32) hours after intravenous and oral administration, respectively. The bioavailability of phenylbutazone paste administered orally was 61 (7) per cent (corrected by the t1/2 beta) and relatively slow absorption was observed, as indicated by a time of maximum drug concentration (tmax) of 3.47 (0.39) hours and a mean absorption time (MAT) of 10.4 (8.61) hours. The concentration of oxyphenbutazone in plasma was low and the ratio of the areas under the curve (AUC) of oxyphenbutazone to phenylbutazone was approximately 0.02:1 after both intravenous and oral administration. Thromboxane B2 generation in the platelets was significantly inhibited (P < 0.05) from one to 12 hours after intravenous administration and from two to 12 hours after oral administration. The results suggest that phenylbutazone is a potentially useful non-steroidal anti-inflammatory drug for use in goats by either route of administration.

To determine if inhibition of a rabbit aorta contracting substance (RCS) corresponds to inhibition of thromboxane synthetase human washed platelets were stimulated with thrombin. RCS formation was bioassayed on rabbit aorta strips in Tyrode solution containing selective blocking agents and thromboxane (TX)B2 in the same probes by specific radioimmunoassay. Dazoxiben inhibited the formation of TXB2 but not of RCS, whereas indomethacin inhibited both RCS and TX formation. The data indicate that the rabbit aorta cannot be used alone to predict inhibition of TX formation with specific TX synthetase inhibitors.

Ten weeks old male Sprague-Dawley rats were used. One mg/kg of a calfskin type III collagen was injected into a tail vein under pentobarbital anesthesia, and the electrocardiogram (ECG) was recorded via leads I, II and III for 10 min. Abnormal ECG patterns, i.e., ST-T changes and incidence of arrhythmia, were shown after collagen injection, and some rats suffered cardiac arrest. Oral administration of (E)-7-phenyl-7-(3-pyridyl)-6-heptenoic acid (CV-4151), a thromboxane synthetase inhibitor, at the dose of 10 mg/kg two hr before the collagen injection made the ST-T changes small, and it reduced the incidence of cardiac arrest. The effect of CV-4151 was greater than that of 30 mg/kg of ticlopidine with the same type of treatment. Neither CV-4151 nor ticlopidine had any affect on collagen-induced decreases in the blood platelet count. However, plasma thromboxane (TX) B2 level in the CV-4151-treated group was very low in comparison with those in both the control and ticlopidine-treated groups at 10 min after the collagen injection. These findings indicate that TXA2 may contribute, at least partly, to the collagen-induced ECG changes and indicate that CV-4151 might be a favorable agent for the prevention of TXA2-mediated cardiac ischemia.

Thromboxanes (TX) are known to have damaging effect on a liver but their influence on the cell death, in particular on hepatocyte apoptosis and its morphological features is not investigated enough. Cell death of the rat hepatocytes was investigated in primary culture by double vital staining with fluorescent nuclear stains Hoechst 33342 and propidium iodide and by electron microscopy. It was established that exogenous Tx B2 increases the amount of hepatocytes with early stages of apoptosis - the condensed chromatin and nucleus and cell size reduction. The changes in a percentage of hepatocytes with morphological features of the late stages of apoptosis - fragmented nuclei and division on apoptotic bodies were not revealed. Tx B2 intensified the carbon tetrachloride action on hepatocyte apoptotic death and increased chromatin condensation. Tx B2 application to hepatocytes injured by chenodeoxycholic acid significantly increased the amount of cells with a final stage ofapoptosis.

Background: The combined effects of glyphosate and hard water on chronic kidney disease of unknown etiology (CDKu) have attracted much interest, but the mechanisms remain unknown. Cytoplasmic phospholipase A₂ (cPLA₂) plays a key role in the acute and chronic inflammatory reactions. This study explored the effect of glyphosate combined with hard water on renal tubules and the possible targets and mechanisms involved.

Methods: In vivo experiments were conducted to investigate the synergistic effects and potential mechanisms of glyphosate and hard water on renal tubular injury in mice.

Results: Administration of glyphosate in mice resulted in elevated levels of β2-microglobulin (β₂-MG), albumin (ALB), and serum creatinine (SCr) compared to control mice. This increase was more pronounce when glyphosate was combined with hard water. In the glyphosate-treated mice, small areas of the kidney revealed fibroblast proliferation and vacuolar degeneration, particularly at the higher dose of 400 mg/kg glyphosate. However, the combination of glyphosate and hard water induced an even greater degree of pathological changes in the kidney. Immunofluorescence and western blot analyses showed that glyphosate and hard water had a coordinated effect on calcium ions (Ca²⁺)-activated phospholipase A₂ and the activation may play a key role in inflammation and renal tubular injury. Exposure to glyphosate alone or glyphosate plus hard water increased the levels of oxidative stress markers and inflammatory biomarkers, namely, thromboxane A₂ (TX-A₂), leukotriene B₄ (LTB₄), prostaglandin E₂ (PGE₂), nitric oxide synthase (NOS), and nitric oxide (NO). Parameters of oxidative stress, including the levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were decreased. Further analysis showed that the levels of these biomarkers were significantly different between the mice treated with glyphosate plus hard water and the mice treated with glyphosate alone.

Conclusions: These findings suggested that hard water combined with glyphosate can induce renal tubular injury in mice, and this may involve mitogen-activated protein kinases (MAPK)/cytosolic phospholipase A₂ (cPLA₂)/arachidonic acid (AA) and its downstream factors.

Keywords: Glyphosate; calcium sensitive receptor; cytosolic phospholipase A2; hard water; renal tubule.

BACKGROUND

The intratracheal instillation of recombinant human interleukin-5 (rhIL-5) into isolated lungs from sensitized and antigen-boosted guinea pigs is followed by enhanced responses to platelet-activating factor (PAF).

METHODS

Modulation by nedocromil sodium of rhIL-5-dependent hyperresponsiveness to PAF was investigated. Perfused lungs from guinea pigs actively sensitized to ovalbumin were injected intratracheally with 300 ng rhIL-5 followed by PAF (10 and 100 ng intraarterially).

RESULTS

No inhibition of rhIL-5-induced increased bronchoconstriction and release of thromboxane (TX)B2 and histamine by PAF was observed when nedocromil sodium (10 mumol/L) was perfused into the lungs. In contrast, when guinea pigs were treated for 2 days (30 mg/kg twice a day), eosinophil recruitment into the bronchoalveolar lavage fluid and hyperresponsiveness to PAF were markedly reduced (100% [p < 0.001]; around 70% [p < 0.05] and around 90% [p < 0.001] inhibition for bronchoconstriction, TXB2 and histamine release, respectively).

CONCLUSIONS

Our results indicate that nedocromil sodium prevents the rhIL-5-induced lung hyperresponsiveness to PAF and the eosinophil migration into the airways only when it is administered in vivo. It is thus suggested that nedocromil sodium interferes with the development of airway inflammation by inhibiting the recruitment in the lung of a target on which PAF and IL-5 interact.

Concentration-dependent relaxation (6-70%) of segments of human saphenous veins under isometric conditions could be demonstrated with cumulative concentrations of isosorbide dinitrate (ISDN) and Glycerol trinitrate GTN (10(-9)-10(-5) M). Vein segments were obtained during coronary by-pass surgery. Nitrate (GTN)-induced relaxation was accompanied by a 2- to 3-fold increase of cyclic GMP content in the vessel walls. However, no change of concentrations in the vessel walls could be determined for the metabolites of prostaglandines: (PG E2, PG F2 alpha, TX B2, 6-keto-PGF1 alpha). Pretreatment of patients with 40 mg ISDN (standard release formulation) 4 times daily for 1 week prior to surgery with the last dose 1 hour before harvesting the vein segments did not influence relaxation. by ISDN. Immersion of vein segments for 1 hour in buffer solution containing 10(-6) M ISDN (= therapeutic concentration) prior to relaxation with cumulative concentrations of ISDN did not influence relaxation either. Induction of in vitro tolerance required ISDN concentrations which exceeded the range achieved under therapeutic conditions: 4.4 x 10(-4) M. This in vitro tolerance could be widely reversed by 10 mM N-Acetylcysteine (NAC) suggesting involvement of sulfhydril (SH) groups. Since tolerance in this experimental model was not seen under concentrations achieved in patients it seems likely that clinical tolerance is caused by activation of counterregulatory forces.

In ex vivo experiments we have investigated the effects of single oral administrations of aspirin (100 or 1000 mg) or ibuprofen (200 or 1200 mg) on the formation of immunoreactive thromboxane (TX) B2 and cysteinyl-leukotrienes (LT) by whole human blood in vitro. Whole human blood was allowed to clot spontaneously and in addition, in the presence of the chemotactic tripeptide f-Met-Leu-Phe (FMLP, 1 microM), or the non-physiological ionophore A 23187 (10 microM). Oral pretreatment with aspirin or ibuprofen led to dose-dependent inhibition of the TXB2 production in the presence of any of the stimuli used. After drug pretreatment the cysteinyl-LT production was not significantly enhanced in blood stimulated with FMLP or allowed to clot spontaneously as compared to values prior to oral drug administration. However, pronounced inhibition of the cyclooxygenase pathway was accompanied by an enhanced cysteinyl-LT formation when ionophore A 23187 was used as a stimulus. This could also be shown in experiments where the cyclooxygenase inhibitors were added in vitro. The higher oral dose of aspirin reduced the ex vivo cysteinyl-LT production in spontaneously clotting blood. By reverse phase HPLC immunoreactive cysteinyl-LT were characterized as a mixture of LTD4 and LTE4 as well as small amounts of LTC4. The data show that in the presence of therapeutic cyclooxygenase inhibitors no enhanced formation of cysteinyl-LT occurs in human blood in vitro after physiological stimuli such as contact activation of the clotting cascade or FMLP.

This study compares biological activities of racemic ibuprofen (rac-IBU) and its S(+) and R(-) enantiomeres in human platelet and polymorphonuclear cells (PMN). Rac-IBU inhibited cyclooxygenase-related platelet functions (aggregation, thromboxane (TX) B2 formation) in vitro, the S-(+) enantiomer being 40-100-times more active than the R-(-) form. rac-IBU also inhibited PMN functions (O2- generation, beta-glucuronidase release). These effects in PMN were not stereospecific. The data suggest cyclooxygenase-independent actions of ibuprofen in human PMN which may contribute to its antiinflammatory effects in vivo.

The effects of the H1-antihistamines astemizole, oxatomide and pyrilamine, of the calmodulin antagonists trifluoperazine and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), on the ionophore A23187 (5 mumol/l)-induced release of cysteinyl-leukotrienes (LT) and thromboxane (TX) B2 from mixed human leukocytes were investigated in comparison to those of the cyclooxygenase inhibitor indomethacin and the lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA). In contrast to pyrilamine both astemizole and oxatomide inhibited the release of cysteinyl-LT and TXB2 with IC50 values between 4 and 23 mumol/l. Both astemizole and oxatomide were about twice as effective in inhibiting cysteinyl-LT release as compared to TXB2 release. Similar to astemizole and oxatomide the calmodulin antagonists trifluoperazine and W-7 inhibited the eicosanoid release. W-7 was, however, clearly less effective and in contrast to trifluoperazine no difference was observed in its potency to inhibit cysteinyl-LT or TXB2 release. The H1-antihistamines, astemizole and oxatomide as well as the calmodulin antagonists did not cause intracellular retention of the eicosanoids tested. The reference compounds indomethacin and NDGA proved to be the most potent inhibitors. The results demonstrate that the therapeutic antihistamines astemizole and oxatomide as well as the classical calmodulin antagonists trifluoperazine and W-7 are able to inhibit eicosanoid formation.

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.

Changes of plasma thromboxane level in subarachnoid haemorrhage (SAH) were studied clinically and experimentally using 11-dehydro-thromboxane B2 (11 DTX) as a measuring index. 11 DTX is a major long-lived metabolite formed from thromboxane (TX) B2, and is said to be a more reliable parameter for detecting TXA2 production in biological systems. In this clinical study, blood was sampled from the cubital vein of 10 SAH patients on the earliest possible day (day 0 or 1), during the vasospasm predilection period (day 7 approximately 11) and in the chronic stage (day 16 approximately 32). Plasma concentrations of 11 DTX and 6-keto-PGF 1 alpha were measured in clinical cases. A canine SAH model was produced by the two haemorrhage methods and blood was sampled from the superior sagittal sinus before and on day 4 of the first cisternal blood injection. 11 DTX, TXB2 and platelet function were examined in each sample. In the clinical studies, plasma 11 DTX levels tended to be higher in the early stage of SAH but decreased thereafter to the normal or lower level. Plasma concentrations of 6-keto-PGF1 alpha tended to decrease mildly during the vasospasm predilection period. In the experimental study, neither definite change of plasma 11 DTX level nor neurological deficit could be induced by the mimic SAH, while an increase in platelet aggregability and narrowing of the basilar artery were observed. 11 DTX was inferred to be a more reliable parameter of TX biosynthesis than TXB2.

The effects of endotoxin pretreatment on induction of in vivo tolerance to endotoxin lethality, and on in vitro stimulated peritoneal macrophage mediators, thromboxane (TX)B2 and interleukin 6 (IL-6) were investigated. Rats were given i.p. injections of S. enteritidis endotoxin on days 1 (100 micrograms/kg) and 2 (500 micrograms/kg), respectively. After 5 days, or after 2-8 weeks of initial pretreatment, either endotoxin-induced mortality was assessed, or peritoneal cells were harvested for the in vitro studies. Endotoxin tolerant rats were resistant (p < .05) to endotoxin lethality for 2 weeks after initial induction of tolerance. In vitro studies with peritoneal macrophages demonstrated that endotoxin or monophosphoryl lipid A stimulated (p < .05) TXB2 production. However, peritoneal cells harvested from endotoxin tolerant rats exhibited suppressed (*p < .05) TXB2 production to both stimuli which persisted for at least 8 weeks. Endotoxin stimulated (p < .05) in vitro levels of IL-6 in control cells, but in contrast to the suppressed TXB2 production in tolerance, also stimulated (p < .05) in vitro IL-6 in the endotoxin tolerant group. Paradoxically, lipid A did not induce IL-6 production in either group. These composite observations suggest that during endotoxin tolerance neither in vitro peritoneal macrophage TXB2 nor IL-6 synthesis temporally correlate with in vivo resistance to lethality.

The increased TXA2 and decreased PGI2 seen in the toxemic pregnancies suggest the imbalance of arachidonic metabolism. Thromboxane (TX) B2 was thought to be a suitable parameter of TXA2 production in vivo. However, recently it has come to be recognized that a large amount of TXB2 is readily produced and decomposed to 11-dehydro TXB2 during blood sampling. In this study, a new RIA method was established, capable of measuring the urinary 11-dehydro TXB2 level. (1) The samples were measured with a 125I-labeled RIA kit for 11-dehydro TXB2 (Amersham, U.K.). In this assay system a highly specific antibody to 11-dehydro TXB2 was used. (2) The values for urinary 11-dehydro TXB2 measured by the RIA correlated closely with those measured by gas chromatography-mass spectrometry (r = 0.95). (3) The mean 11-dehydro TXB2 value in non pregnant was 2.62 +/- 1.71ng/mg Cr, The mean values in the first, second and third trimesters of pregnancy were 4.57 +/- 2.45ng/mg Cr, 5.75 +/- 2.81ng/mg Cr, 6.33 +/- 2.60ng/mg Cr, respectively. (4) The mean 11-dehydro TXB2 value in toxemic pregnancy was 4.13 +/- 1.86ng/mg Cr, which was significantly lower than that in normal pregnancies. (5) There was a significant negative correlation (p less than 0.0001) between the urinary 11-dehydro TXB2 concentration and the blood pressure.

In 12 patients (8 males, 4 females; 59.4 +/- 6.2 years) with clinically manifest atherosclerosis (peripheral vascular disease stage II according to Fontaine and coronary heart disease) without any risk factor and 6 controls (4 males, 2 females; 58.5 +/- 7.06 years) autologous platelets were labelled using 100 microCi 111-In-oxine. In parallel, serum- and plasma-thromboxane (TX) B2 and conversion of exogenous radiolabelled arachidonic acid towards TXB2 were determined. No difference in labelling efficiency and recovery was noted. Platelet half-life was significantly (p less than 0.01) shortened in the atherosclerotics. Gamma-camera images were obtained during the first 64 minutes after reinjection as well as 2, 6, 18, 24 and daily up to 1 week after reinjection of autologous radiolabelled platelets. No difference between the patients suffering from atherosclerosis--having either visible atherosclerotic lesions or not--could be discovered. Serum-TXB2 was comparable, whereas plasma-TXB2 showed a trend towards an increase and the conversion from exogenous 14C-AA to 14C-TXB2 was increased in atherosclerosis.

The effect of Salmonella enteritidis endotoxin on in vitro rat neutrophil cyclo-oxygenase and lipoxygenase metabolism, phagocytic activity, superoxide (O2-) generation, and microbicidal activity was investigated. Incubation of polymorphonuclear leukocytes (PMN) with 5, 25, and 50 micrograms of endotoxin significantly enhanced synthesis of immunoreactive (i) leukotriene (LT)C4/D4 and thromboxane (Tx)B2 (P less than 0.001) as compared to control cells. Endotoxin 5 micrograms/ml produced optimal stimulation of the arachidonic acid metabolites. Calcium ionophore, A23187, significantly enhanced iLTC4/D4 and iTxB2 synthesis more than that elicited with endotoxin. Although phagocytic function was not significantly altered by endotoxin, intracellular killing of C. albicans demonstrated enhanced microbicidal activity at 5 micrograms/ml of endotoxin. Superoxide generation was significantly enhanced in neutrophils stimulated with phorbol myristate acetate (PMA). Endotoxin (5 micrograms/ml) further potentiated superoxide generation by these cells when stimulated by PMA. These findings demonstrate that endotoxin directly enhances neutrophil iLTC4/D4 and iTxB2 synthesis. The enhanced arachidonic acid metabolism elicited by endotoxin in these cells parallels increased microbicidal activity and superoxide generation.

OBJECTIVE

Rotating shift work has been reported to increase the risk of cardiovascular diseases. Vascular endothelial dysfunction and platelet activation are among the leading causes of thrombus formation in patients with myocardial infarction or stroke. Endothelial function has been shown to be impaired immediately after night-shift work; however, it is not known whether platelets are also activated. The aim of this study was to investigate the acute impact of night-shift work on platelet function.

METHODS

This observational study included 11 healthy medical staff members (seven women, median age 32 years). We examined each subject's platelet aggregation rates and the serum concentrations of eicosanoid mediators after night-shift work and on day-shift work without preceding night-shift work (baseline).

RESULTS

Platelet aggregation did not differ from baseline levels after night-shift work. However, serum cyclooxygenase (COX)-metabolized eicosanoid mediators, particularly thromboxane (Tx) B2 (a stable metabolite of TxA2 and the most important marker of platelet activation), were significantly higher after the night-shift than at baseline (median 65.3 vs 180.4 ng/ml).

CONCLUSIONS

Although platelet aggregation did not increase, there was an increase in serum COX-metabolized eicosanoid mediators such as TxB2 in healthy medical staff after night-shift work. This platelet hypersensitivity may be one of the mechanisms underlying the significant association between night-shift work and adverse cardiovascular outcomes.

We tested the hypothesis that tumor necrosis factor-alpha (TNF-alpha) primes the hemodynamic response to the neutrophil agonist N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) in lungs isolated from guinea pigs. Lungs were isolated from animals 18 h after injection of TNF-alpha (3.20 x 10(5) U/kg ip). The infusion of FMLP (300 nM) into lungs isolated after the intraperitoneal administration of TNF-alpha resulted in increases in lung weight, lung (wet-dry)-to-dry weight ratio [(wet-dry)/dry wt], pulmonary capillary pressure, lung myeloperoxidase activity and perfusate thromboxane (Tx)B2 levels. Animals pretreated with the maximal possible amount of endotoxin in the TNF-alpha (1.7 pg endotoxin) did not respond to FMLP. WEB-2086 (37 microM), a platelet-activating factor (PAF) receptor antagonist, added to the perfusate attenuated the hemodynamic and TxA2 response to FMLP. Dazoxiben (0.5 mM), a TxA2 synthetase inhibitor, prevented the FMLP effect. Polyethylene glycol (PEG)-catalase (500 U/ml) added to the perfusate did not affect the FMLP response; however, PEG-catalase (10(5) U/kg) given intraperitoneally with the TNF-alpha decreased the synergism induced by TNF-alpha with FMLP. The data suggest that TNF-alpha primes the lung to the effects of FMLP by increasing the population of resident neutrophils in the lung and/or by in vivo oxidant generation. The pulmonary hemodynamic response and lung edema induced by FMLP are mediated by PAF and TxA2.

We examined the effects of continuous intravenous infusion of nitroglycerin (NTG) on lung dysfunction induced by endotoxemia in awake sheep chronically instrumented with lung lymph fistula. We measured the responses of hemodynamics, lung lymph balance, and thromboxane (Tx)B2 and 6-keto-prostaglandin (PG) F1 alpha levels in plasma and lung lymph to endotoxin administration (1 microgram/kg, intravenously [IV], over 30 min) with and without continuous infusion of NTG (1 microgram/kg/min). Continuous infusion of NTG alone (n = 5) over 5 hr did not significantly alter systemic, pulmonary hemodynamics, and/or lung lymph fluid filtration. Infusion of endotoxin alone (n = 7) caused remarkable increases in pulmonary artery pressure (Ppa) and lung lymph flow (Qlym) in the early phase. Continuous infusion of NTG (n = 6) significantly prevented the early increases in Ppa and Qlym after endotoxin. The increased values of TxB2 and 6-keto-PGF1 alpha in both plasma and lung lymph after endotoxemia showed the same increases in groups with and without NTG. These findings suggest that the reduction of pulmonary artery pressure induced by NTG decreased the filtration of fluid into the lungs associated with endotoxemia in sheep, and that the mechanism of vasodilating action of NTG is not due to modifications of constrictive-dilated cyclo-oxygenase products of arachidonate, such as TxA2 and PGI2.

Different layers of rabbit large and small intestine display different peptide sensitivity and different profiles of eicosanoid release. Isolated perfused mesenteric pedicle alone, with muscularis/submucosa or with muscularis and mucosa from normal small bowel, normal colon, or inflamed colon were stimulated with bradykinin (BK) or n-formyl-methionyl-leucyl-phenylalanine (fMLP). Released prostaglandin (PG)E2, thromboxane (Tx)B2, and leukotriene (LT)B4 were assayed using extensively validated radioimmunoassays. In rabbit colon, PGE2 arises primarily from the mesentery, while in small intestine the muscularis/mucosa releases 70-80% of the total PGE2. BK releases no significant thromboxane from healthy colon, although both muscularis/submucosa and mucosa respond in inflamed colon. In contrast, fMLP stimulates thromboxane from muscularis/submucosa and mucosa of even healthy colon, while release is greatly potentiated in inflammation. Lipoxygenase in the colon is regulated differently than cyclooxygenase; it is not stimulated by BK in either healthy or inflamed colon. fMLP releases equal amounts of LTB4 from healthy and inflamed colon, but release was primarily from healthy colonic mucosa, whereas it was distributed throughout mesenteric pedicle, muscularis, and mucosa in inflamed colon. The ability of normal colonic mucosa to release proinflammatory LTB4 in response to a chemotactic factor (fMLP) produced by enteric bacteria suggests a possible role for these compounds as a stimulus for inflammation in some patients with inflammatory bowel disease.

Aortic and coronary sinus platelet aggregation, thromboxane A2 (TXA2) and prostacyclin (PG12) levels were studied in fourteen patients of stable angina (SA), six of vasopastic angina (VA) and six control subjects (C). Patients of SA were studied at rest and during incremental atrial pacing and patients with VA were studied at rest and during various stages of vasospasm. Platelet aggregation was studied with different working concentrations of ADP, epinephrine and collagen. TX A2 and PGI2 concentrations were estimated by measuring levels of their stable metabolites viz. thromboxane B2 (TXB2) and 6-keto prostaglandin F1 alpha (PGF1 alpha) respectively. Platelet aggregation was increased in SA and VA patients (p < 0.01) and further increase was seen during vasospasm (p < 0.001). However, it failed to increase on incremental atrial pacing. Similarly, TXB2 and PGF1 alpha levels were raised in SA and VA patients. While TXB2 further increased during vasospasm but not during atrial pacing. PGF1 infinity failed to rise with either. Thus platelets are in an activated state in SA and VA. This activated state is a cause and not an effect in SA and VA. An imbalance in the levels of TXA2 and PG12 could account for the vasospasm.

Marmoset wasting syndrome (MWS) is clinically characterized by progressive weight loss. Although morbidity and mortality of MWS are relatively high in captive marmosets, its causes remain unknown. Lipid mediators are bioactive metabolites which are produced from polyunsaturated fatty acids, such as arachidonic acid (AA) and eicosapentaenoic acid. These lipid metabolites regulate a wide range of inflammatory responses and they are excreted into the urine. As urinary lipid profiles reflect systemic inflammatory conditions, we comprehensively measured the levels of 141 types of lipid metabolites in the urines obtained from healthy common marmoset (Callithrix jacchus) (N = 7) or marmosets with MWS (N = 7). We found that 41 types of metabolites were detected in all urine samples of both groups. Among them, AA-derived metabolites accounted for 63% (26/41 types) of all detected metabolites. Notably, the levels of AA-derived prostaglandin (PG) E2, PGF2α, thromboxane (TX) B2 and F2-isoprostanes significantly increased in the urine samples of marmosets with MWS. In this study, we found some urinary lipid metabolites which may be involved in the development of MWS. Although the cause of MWS remains unclear, our findings may provide some insight into understanding the mechanisms of development of MWS.

Using 50 mongrel dogs with alveolar flooding produced by oleic acid administration, the possible roles of vasoactive cyclooxygenase products on intrapulmonary shunt flow (QS/QT) and extravascular lung water (ETVI) in acutely injured lungs were assessed. Suppressing cyclooxygenase activity with indomethacin administration diminished the concentrations of thromboxane (TX) B2 and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) in arterial blood, resulting in a significant reduction in QS/QT. Furthermore, indomethacin completely suppressed the increase in ETVI. Inhibition of TXA2 generation by OKY-046 (thromboxane A2 synthase blocker) diminished the concentration of TXB2 while increasing that of 6-keto-PGF1 alpha in blood. Administration of either OKY-046 or synthetic prostacyclin (PGI2) markedly enhanced QS/QT, in association with an increase in ETVI. In conclusion, the potent vasodilator prostacyclin was considered to enhance shunt flow, leading to the augmentation of edema formation.