Anandamide transport inhibition by the vanilloid agonist olvanil

The structural similarities between the anandamide transport inhibitor N-(4-hydroxyphenyl)-arachidonylamide (AM404) and the synthetic vanilloid agonist olvanil [(N-vanillyl)-9-oleamide], prompted us to investigate the possibility that olvanil may interfere with anandamide transport. The intracellular accumulation of [3H]anandamide by human astrocytoma cells was prevented by olvanil with a Ki value of 14.1+/-7.1 microM. By contrast, capsaicin [(8-methyl-N-vanillyl)-6-noneamide], a plant-derived vanilloid agonist, and capsazepine (N-[2-(4-chlorophenyl)ethyl]-1,3,4,5-tetrahydro-7,8-dihydroxy-2 H-2-benzazepine-2-carbothioamide), a vanilloid antagonist, had no such effect (Ki > 100 microM). These results indicate that, although less potent than AM404 (Ki 2.1+/-0.2 microM), olvanil may reduce anandamide clearance at concentrations similar to those needed for vanilloid receptor activation.

Biochemistry of the endogenous ligands of cannabinoid receptors

In 1992 the discovery of the first endogenous ligand of cannabinoid receptors, anandamide, provided conclusive support to the hypothesis that an "endogenous cannabinoid regulatory system" exists in mammalian nervous tissue. Anandamide (N-arachidonoyl-ethanolamine) was the first of a series of long-chain fatty acid derivatives, including two other polyunsaturated N-acylethanolamines and 2-arachidonoyl-glycerol, found to exert cannabimimetic properties in either central or peripheral tissues. Here we review the current knowledge on the biochemical bases of the formation and inactivation of endogenous cannabinoid ligands as well as of their interaction with cannabinoid receptor subtypes.

Inhibition of the synthesis of eicosanoid-like substances in a human oral cancer cell line by interferon-gamma and eicosapentaenoic acid

The objectives were to examine the production of eicosanoids in a Chinese human oral cancer cell line (OEC-M1) and to test the effects of interferon-gamma (IFN-gamma), eicosapentaenoic acid (EPA) and enzyme inhibitors on this biosynthesis. The eicosanoids were identified by reverse phase-high performance liquid chromatography. Two predominant peaks appeared in the chromatograms. One compound (P-1) was identified by ultraviolet absorption at a lambda(max) of 278nm with shoulders at 272 and 284nm. The other compound (P-2) was identified by ultraviolet absorption at a lambda(max) of 284 nm with shoulders at 278 and 290 nm. The production of P- was significantly inhibited by the addition of IFN-gamma (200 and 400 U/ml), and EPA (10 to 40 microM). It was only partially inhibited (p < 0.05) by indomethacin (INDO) (0.5 and 1 microM), nordihydroguaiaretic acid (NDGA) (30 and 60 microM/ml), and eicosa-5,8,11,14-tetraynoic acid (ETYA) (20-60 microM). It was almost completely inhibited by indomethacin (2 and 3 microM), and dexamethasone (0.6 and 6 microM). The production of P-2 was almost completely inhibited by IFN-gamma (200 and 400 U/ml), and partially inhibited (p < 0.05) by EPA (10 and 20 microM), NDGA (30 and 60 microM), ETYA (20 and 40 microM), dexamethasone (0.6 and 6 microM). The production of both peaks was significantly reduced by excluding arachidonic acid (AA), and almost completely inhibited by heating at 100 degrees C for 10 min during incubation. These results demonstrate that two eicosanoid-like compounds are synthesized by the OEC-M cell line and that their production can be modulated by IFN-gamma, EPA, indomethacin, NDGA, ETYA, and dexamethasone.

Actions of general anaesthetics and arachidonic pathway inhibitors on K+ currents activated by volatile anaesthetics and FMRFamide in molluscan neurones

1. K+ currents activated by volatile general anaesthetics (IK(An)) and by the neuropeptide FMRFamide (IK(FMRFa)) were studied under voltage clamp in isolated identified neurones from the pond snail Lymnaea stagnalis. 2. IK(An) was activated by all the volatile anaesthetics studied. The maximal responses varied from agent to agent, with halothane sevoflurane > isoflurane > enflurane approximately chloroform. 3. IK(An) was inhibited rather than activated by the n-alcohols from hexanol to dodecanol and by the 6- and 8-carbon cycloalcohols. The n-alcohols exhibited a cutoff effect, with dodecanol being unable to half-inhibit IK(An). 4. Unlike IK(An) which did not desensitize at reasonable halothane concentrations, IK(FMRFa) desensitized at most FMRFamide concentrations studied. This desensitization could be substantially removed by halothane. Nonetheless, both IK(An) and IK(FMRFa) had similar sensitivities to the potassium channel blockers tetraethylammonium and 4-aminopyridine, consistent with both currents flowing through the same channels. Responses to low concentrations of halothane and FMRFamide showed synergy. 5. The phospholipase A2 inhibitor aristolochic acid inhibited IK(An), consistent with a role for arachidonic acid (AA). The lipoxygenase and cyclooxygenase inhibitor nordihydroguaiaretic acid blocked IK(FMRFa) but did not affect IK(An). IK(An) and IK(FMRFa) were little affected by the cyclooxygenase inhibitor indomethacin. These findings suggest that neither lipoxygenase nor cyclooxygenase pathways of AA metabolism are involved in the anaesthetic activation of IK(An. 6. Inhibitors of a third, cytochrome P450-mediated, pathway of AA metabolism (clotrimazole and econazole) potently blocked IK(An), suggesting possible roles for certain cytochrome P450 isoforms in the activation of IK(An).

Prednisolone inhibits synthesis of 5-H(P)ETE in eosinophils from asthmatic patients during a wheezing attack but not during remission

To estimate the effect of prednisolone on 5-lipoxygenase activity in eosinophils obtained from asthmatic patients, cytosolic levels of 5-H(P)ETE and Ca2+ were measured in the eosinophils which were exposed to prednisolone in vitro and in vivo. The mean level of 5-H(P)ETE during a wheezing attack was significantly lower in the patients who had received intravenous prednisolone (500 mg/day). Incubation with prednisolone in vitro caused a dose-dependent decrease in the cytosolic levels of 5-H(P)ETE and Ca2+ in eosinophils obtained during the wheezing attack, but not in the eosinophils obtained from during remission. Results suggest that prednisolone inhibits the level of 5-H(P)ETE in the eosinophil cytosols of asthmatic patients during a wheezing attack, probably by inhibition of 5-lipoxygenase activity which is involved in the reduction of the influx of Ca2+.

Functional role of high-affinity anandamide transport, as revealed by selective inhibition

Anandamide, an endogenous ligand for central cannabinoid receptors, is released from neurons on depolarization and rapidly inactivated. Anandamide inactivation is not completely understood, but it may occur by transport into cells or by enzymatic hydrolysis. The compound N-(4-hydroxyphenyl)arachidonylamide (AM404) was shown to inhibit high-affinity anandamide accumulation in rat neurons and astrocytes in vitro, an indication that this accumulation resulted from carrier-mediated transport. Although AM404 did not activate cannabinoid receptors or inhibit anandamide hydrolysis, it enhanced receptor-mediated anandamide responses in vitro and in vivo. The data indicate that carrier-mediated transport may be essential for termination of the biological effects of anandamide, and may represent a potential drug target.

Endotoxin stimulates in vitro pituitary growth hormone release in eicosanoid-dependent manner

OBJECTIVE

To investigate the signal transduction pathways by which endotoxin stimulates in vitro pituitary cell growth hormone (GH) release.

ANIMALS

Pituitary cell cultures derived from 6 sheep.

PROCEDURE

Signal transduction pathways involved in endotoxin-mediated GH release from sheep pituitary cell cultures were evaluated by the use of specific blockers of arachidonic acid and its metabolites, extracellular calcium, protein kinase C, and protein kinase A. Cell cultures were exposed to the specific blockers in the presence or absence of endotoxin (Escherichia coli O55:B5, 10 micrograms/ml) for 24 hours. In addition, effects of endotoxin on GH cell content and GH mRNA values were determined.

RESULTS

Nordihydroquairetic acid (lipoxygenase blocker, 10 microM, 30 microM) and eicosatetraynoic acid (arachidonic acid competitor, 10 microM) decreased endotoxin-stimulated GH release. The calcium channel blocker verapamil (25 microM) decreased baseline and endotoxin-stimulated GH release. Phorbol myristate acetate-induced down-regulation of protein kinase C, indomethacin, or the protein kinase A blocker H89 did not alter endotoxin-stimulated GH release. Endotoxin increased GH mRNA values by 50.1 +/- 6.0%, but the cell content of GH was not affected.

CONCLUSIONS

A direct effect of endotoxin on the pituitary gland to stimulate GH secretion was evident, an effect mediated predominantly by arachidonic acid and its metabolites through the lipoxygenase pathway. Endotoxin-stimulated GH release requires extracellular calcium and is associated with increased cell GH mRNA content.

CLINICAL RELEVANCE

A better understanding of the signal transduction pathways involved in endotoxin-mediated effects will allow more appropriate therapeutic intervention in clinical cases of endotoxemia.

Triclosan reduces prostaglandin biosynthesis in human gingival fibroblasts challenged with interleukin-1 in vitro

The effect of the toothpaste ingredient triclosan (2,4,4'-trichloro-2'-hydroxyldiphenyl ether) on the prostaglandins biosynthesis in human gingival fibroblasts challenged with interleukin-1beta (IL-1beta) or tumor necrosis factor alpha (TNFalpha) was studied in vitro. When gingival fibroblasts were treated simultaneously with triclosan and IL-1beta, the stimulatory effect of IL-1beta on prostaglandin E2 (PGE2) and PGI2 formation was reduced in a dose-dependent manner by triclosan. Triclosan also reduced the PGE2 formation induced by TNFalpha. Furthermore, the capacity of IL-1beta to induce release of [3H] arachidonic acid from prelabelled gingival fibroblasts was reduced in the presence of triclosan. Addition of exogenous unlabelled arachidonic acid (AA) to the cells resulted in enhanced PGE2 formation which was reduced by triclosan. The upregulation of the metabolism of AA to PGE2 induced by IL-1beta, was markedly reduced in the presence of triclosan. The study indicates that the stimulatory effect of IL-1beta on prostanoid formation (PGE2, PGI2) in human gingival fibroblasts was diminished in the presence of triclosan partly at the level of phospholipase A2 and partly at the level of cyclooxygenase. The present data that triclosan, in vitro, inhibits the production of inflammatory mediators such as prostaglandins suggests that this can be an aspect of its clinical effect on gingivitis, in addition to its antibacterial effect.

CD69-induced monocyte apoptosis involves multiple nonredundant signaling pathways

Simultaneous stimulation of human monocytes/macrophages or THP1 cells with LPS and an antibody specific for the activation marker CD69 induces apoptosis. Here we demonstrate the involvement of multiple independent signals that are necessary for apoptosis induction. Thus, inhibitors of phospholipase A2 and lipoxygenase prevent apoptosis induction. Similarly, the ADP-ribosylating G-protein-reactive pertussis toxin (PTX) but not a mutant toxin lacking the ADP-ribosylating moiety (mPTX) prevents apoptosis induction. Furthermore, inhibition of NO generation abrogates completely the induction of apoptosis by LPS/CD69 ligation. These three pathways can be dissociated from each other in the sense that interventions on the arachidonic acid metabolism or G proteins do not inhibit the generation of NO and that exogenous NO cannot reverse the inhibition of cell death by inhibitors of phospholipase A2 or PTX. In addition, both PTX and mPTX affect arachidonic acid mobilization only partially, indicating that the apoptosis-inhibitory effect of PTX (which is not shared by mPTX) cannot be explained by its effect on phospholipase A2 activation. Both LPS and anti-CD69 are sufficient on their own to activate cells, as determined by TNF production, NO generation, or arachidonic acid metabolism, but neither LPS nor anti-CD69 can induce apoptosis on their own. Thus, apoptosis induction in this system involves at least three independent signal transduction systems--(i) arachidonic acid metabolism, (ii) NO, and (iii) PTX-sensitive events--each of which is necessary but insufficient to induce monocyte/macrophage apoptosis. These findings underline the complex control of activation-induced apoptosis in cells of the myelomonocytic lineage.

The effect of triclosan on mediators of gingival inflammation

Triclosan (2,4,4',-trichloro-2'-hydroxydiphenylether) is a well-known and widely used nonionic antibacterial agent which has recently been introduced in toothpastes and mouthrinses. The efficacy of triclosan-containing toothpaste and mouthrinse to reduce both plaque and gingivitis in long-term clinical trials has been well documented. Until recently, it was generally assumed that triclosan's effect on gingival inflammation was due to its antimicrobial and anti-plaque effect. It has now become apparent that triclosan may have a direct anti-inflammatory effect on the gingival tissues. Several in vitro studies were conducted to evaluate the effect of triclosan on 4 primary enzymes of the pathways of arachidonic acid metabolism, cyclo-oxygenase 1, cyclo-oxygenase 2, 5-lipoxygenase and 15-lipoxygenase. These pathways lead to the production of known mediators of inflammation such as the prostaglandins, leukotrienes and lipoxins. Triclosan inhibited both cyclooxygenase 1 and cyclo-oxygenase 2 with IC-50 values of 43 microM and 227 microM, respectively. Triclosan also inhibited 5-lipoxygenase with an IC-50 of 43 microM. The 15-lipoxygenase was similarly inhibited by triclosan with an IC-50 of 61 microM. Hence, triclosan has the ability to inhibit both the cyclo-oxygenase and lipoxygenase pathways of arachidonic acid metabolism with similar efficacy. In cell culture experiments, it was found that triclosan inhibited IL-1 beta induced prostaglandin E2 production by human gingival fibroblasts in a concentration dependent manner, and at relatively low concentrations. These data, taken together, indicate that triclosan can inhibit formation of several important mediators of gingival inflammation.(ABSTRACT TRUNCATED AT 250 WORDS)

AM630, a competitive cannabinoid receptor antagonist

AM630 (iodopravadoline), a novel aminoalkylindole, has been found to attenuate the ability of a number of cannabinoids to inhibit electrically-evoked twitches of the mouse isolated vas deferens. It did not block the inhibitory effects of morphine or clonidine on the twitch response. AM630 behaved as a competitive antagonist of CP 55,940, WIN 55,212-2, anandamide and (R)-(+)-arachidonyl-1'-hydroxy-2'-propylamide (AM356), producing rightward shifts in the log concentration response curves of these cannabinoid receptor agonists that were concentration-dependent, essentially parallel and not accompanied by any decrease in the size of maximal response. AM630 also produced concentration-dependent, parallel rightward shifts in the log concentration-response curve of delta 9-THC. However, these shifts were accompanied by a decrease in the maximal response. AM630 was markedly more potent as an antagonist of delta 9-THC and CP 55,940 (Kd = 14.0 and 17.3 nM respectively) than as an antagonist of WIN 55,212-2, AM356 or anandamide (Kd = 36.5, 85.9 and 278.8 nM respectively). These differences in dissociation constant imply that the mouse vas deferens may contain more than one type of cannabinoid receptor. The data also indicate that the receptors for which AM630 has the highest affinity may not be CB1 cannabinoid receptors as the CB1 selective antagonist, SR141716A, is known to be equally potent in attenuating the inhibitory effects of CP 55,940 and anandamide on the twitch response of the mouse vas deferens.

Prilocaine reduces injection pain caused by propofol

Propofol, which is commonly used for outpatient anaesthesia, may evoke pain during infusion. Forty-eight patients (ASA-I-II) undergoing elective uterine dilatation and curettage received randomly in a standardised fashion: A: Propofol mixed with prilocaine; B: Propofol and lidocaine; C: Propofol with prilocaine+lidocaine (equal amounts) or D: Propofol and saline. The final ratio of propofol:local anaesthetic/saline was 9:1 in all mixtures. Pain on injection was significantly decreased in the three groups receiving propofol and local anaesthetic(s) compared to the one given propofol and saline. Propofol is required in greater amounts when mixed with lidocaine than when mixed with saline. A binding between the algesic part of the propofol molecule and the local anaesthetic agent may explain these findings. Another twenty-two comparable patients were given 30 mg of ketorolac or an equal volume of saline intramuscularly 45-60 minutes prior to propofol. Ketorolac given before propofol did not reduce pain on injection. This indicates that inhibition of the cyclooxygenase pathway of arachidonic acid metabolism does not play a major role in the reduction of this pain.

Evaluation of chemopreventive agents in different mechanistic classes using a rat tracheal epithelial cell culture transformation assay

The rat tracheal epithelial (RTE) cell focus inhibition assay was used to identify potential chemopreventive agents. Ninety-nine agents were evaluated for their ability to inhibit benzo[a]pyrene-induced transformation of RTE cells. Freshly isolated RTE cells were exposed to benzo[a]pyrene alone or in combination with a chemopreventive agent. After 30 days in culture, transformed foci were scored and inhibition was quantitated. In these studies, foci formation was inhibited mainly by agents which modulate the initiation of carcinogenesis by altering drug-metabolizing enzymes, inhibiting the binding of benzo[a]pyrene to DNA, enhancing detoxification of activated carcinogens, or by inducing epithelial cell differentiation. Such agents include antioxidants, free radical scavengers, glutathione S-transferase enhancers, vitamins, retinoids, and sulfhydryl compounds. Agents which inhibit ornithine decarboxylase and arachidonic acid metabolism were not as effective. The RTE assay provides important data for agent selection prior to whole animal-screening assays in the development of chemoprevention drugs.

Characterization of ligand binding to the cannabinoid receptor of rat brain membranes using a novel method: application to anandamide

Ligand binding to the cannabinoid receptor of brain membranes has been characterized using [3H]CP 55,940 and the Multiscreen Filtration System. Binding of [3H]CP 55,940 is saturable and reaches equilibrium by 45 min at room temperature. At a concentration of 10 micrograms of membrane protein/well, the KD for [3H]CP 55,940 is 461 pM and the Bmax is 860 fmol/mg of protein. The apparent KD of [3H]CP 55,940 is dependent upon tissue protein concentration, increasing to 2,450 pM at 100 micrograms of membrane protein. Binding of [3H]CP 55,940 is dependent upon the concentration of bovine serum albumin in the buffer; the highest ratio of specific to nonspecific binding occurs between 0.5 and 1.0 mg/ml. The Ki of anandamide, a putative endogenous ligand of the cannabinoid receptor, is 1.3 microM in buffer alone and 143 nM in the presence of 0.15 mM phenylmethylsulfonyl fluoride. When [14C]anandamide is incubated with rat forebrain membranes at room temperature, it is degraded to arachidonic acid; the hydrolysis is inhibited by 0.15 mM phenylmethylsulfonyl fluoride. These results support the hypothesis that anandamide is a high-affinity ligand of the cannabinoid receptor and that it is rapidly degraded by membrane fractions.

Effects of two different inhibitors of the arachidonic acid metabolism on platelet sequestration in endotoxic shock

Metabolites of arachidonic acid are known to play an important part in the pathogenesis of organ injury in endotoxic shock. We compared the effects of the classical cyclooxygenase inhibitor aspirin with that of the dual cyclooxygenase and lipoxygenase inhibitor ketoprofen on the behavior of platelets tagged with 111In-labeled oxine in multiple organs during endotoxin shock. Three groups of sheep (n = 7 in each) were anesthetized before being subjected to endotoxin shock. Group E had no drug treatment (shock controls), group KET received ketoprofen and group ASP received aspirin treatment. In the lungs and in the liver of group E there was a marked sequestration of platelets, which started in both organs immediately after administration of endotoxin and continued throughout the study. In the treated groups, however, the response to endotoxin was both delayed and reduced compared with the untreated shock controls. The first changes in platelet activity were noted after more than 1 h in the treated groups. Four hours after administration of endotoxin, platelet activity (sequestration) had increased in the lungs by 102 +/- 14% in group E, 53 +/- 11% in group ASP and 20 +/- 13% in group KET (P < 0.01, P < 0.01 and P < 0.05 respectively compared to baseline). Corresponding values for the liver were 52 +/- 16% in group E, 22 +/- 19% in group ASP and -2 +/- 12% in group KET (P < 0.01, P < 0.01 and P > 0.05 respectively compared with baseline).(ABSTRACT TRUNCATED AT 250 WORDS)

Antithrombotic activity of clove oil

Clove oil inhibited human platelet aggregation induced by arachidonic acid (AA), platelet-activating factor (PAF) or collagen. Clove oil was a more effective inhibitor for aggregation induced by AA and PAF (IC50:4 and 6 microM respectively) than collagen (IC50: 132 microM). The in vivo experiments in rabbits showed that clove oil (50-100 mg/kg) afforded 100% protection against PAF (11 mg/kg, i.v.) and 70% protection against AA (2.0 mg/kg, i.v.)-induced thrombosis and shock due to pulmonary platelet thrombosis. It also inhibited thromboxane-A2 and 12-HETE production by human platelets incubated with [C14] AA. These results are indicative that clove oil is inhibitory of platelet aggregation and thromboxane synthesis and may act as anti-thrombotic agent.

Inhibitory effect of tetrahydroberberine on platelet aggregation and thrombosis

Tetrahydroberberine (THB), an alkaloid extracted from Corydalis ambigua, inhibited the rabbit platelet aggregation triggered by arachidonic acid (AA), ADP, and collagen with IC50 of 0.86, 1.31, and 1.10 mmol.L-1, respectively. THB reduced the thromboxane B2 (TXB2) generation in rabbit platelet-rich plasma triggered by AA. THB 30 mg.kg-1.d-1 ip for 3 or 5 d restrained the ADP-induced platelet aggregation in rats. THB 30 mg.kg-1.d-1 ip for 1, 3, or 5 d inhibited the AA-induced platelet aggregation in rats. THB 15-30 mg.kg-1 iv showed an inhibition of venous thrombosis in rats. The results show that THB is a potent inhibitor of platelet aggregation in vitro and in vivo and is a promising antithrombotic drug.

Arachidonic acid metabolism by isolated and cultured middle ear epithelial cells from the chinchilla

Thin-layer chromatography was used to examine the metabolism of arachidonic acid and prostaglandins (PGs) in freshly isolated and cultured middle ear epithelial cells from the chinchilla. The freshly isolated cells converted arachidonic acid predominantly to PGE2, while those cells grown in culture for 10 days acquired the ability to convert arachidonic acid to 6-keto-PGF1 alpha, PGD2, and PGE2. Incubation of the isolated cells and primary cultures with acetylsalicylic acid and indomethacin inhibited the formation of these PGs. These findings suggest that studies on the factors regulating arachidonic acid metabolism in middle ear epithelium may help to explain the role of eicosanoids in middle ear secretions, particularly in relation to the pathophysiology of otitis media.

Inhibitors of the arachidonic acid cascade dissociate 48/80-induced Ca2+ influx and Ca2+ release in mast cells

Effects of inhibitors of the arachidonic acid cascade on Ca2+ release from intracellular stores and Ca2+ influx through the plasma membrane during stimulus-secretion coupling were examined using rat peritoneal mast cells loaded with fura-2. Compound 48/80 (48/80) was used as a secretagogue. A phospholipase inhibitor, p-bromophenacyl bromide (PBPB), or a lipoxygenase inhibitor, nordihydroguaiaretic acid (NDGA), inhibited the 48/80 (1 microgram/ml)-induced release of histamine, Ca2+, and Mn2+ influxes, but the cyclooxygenase inhibitor, indomethacin (approximately 50 microM), inhibited neither Ca2+ nor Mn2+ influxes. The Ca2+ release induced by 1 microgram/ml of 48/80 was little inhibited by PBPB, NDGA, or indomethacin. The Ca2+ release was activated and saturated with lower concentrations of 48/80 than was the Ca2+ influx. The percent inhibition of the Ca2+ release by 25 microM PBPB was increased by lowering the concentration of 48/80, but NDGA (10 microM) did not inhibit the Ca2+ release induced by low concentrations of 48/80 (0.03-0.1 microgram/ml). These results suggest that activation of the Ca2+ release and the Ca2+ influx were differently regulated and that full activation of Ca2+ influx needs the arachidonic acid cascade produced by higher concentrations of 48/80 than does the Ca2+ release. Lipoxygenase metabolites of arachidonic acid are potential modulators of the Ca2+ influx.

Reduced endotoxin-induced production of tumor necrosis factor activity by equine peritoneal macrophages exposed to the dual inhibitor of arachidonic acid metabolism, SK & F 86002

The purpose of this study was to determine if a structurally novel dual inhibitor of arachidonic acid metabolism, SK & F 86002, would inhibit the endotoxin-induced production of tumor necrosis factor (TNF) activity by equine peritoneal macrophages. Equine peritoneal macrophages were variously pretreated for 0, 0.5 and 2 h with SK & F 86002 at 10(-9) to 10(-4) molar final concentrations or were left untreated. Then, the macrophages were cultured in vitro in the presence of endotoxin (5 ng/mL). Supernatant media were collected after 4 h and stored at -70 degrees C until assayed for TNF activity and immunoreactive thromboxane B2 (iTxB2). Macrophage supernatant TNF activities were estimated by an in vitro cytotoxicity bioassay using the murine fibrosarcoma cell line, WEHI 164 clone 13. Concentrations of iTxB2 were quantitated by radioimmunoassay. Coincubation of macrophages with SK & F 86002 significantly decreased the subsequent supernatant TNF activity. Concentrations of SK & F 86002 from 10(-7) to 10(-4) molar effectively reduced TNF production when added to macrophages 0 and 0.5 h prior to endotoxin. After 2 h of preincubation, SK & F 86002 significantly reduced supernatant TNF activity at 10(-5) and 10(-4) M concentrations. Supernatant concentrations of iTxB2 were reduced when SK & F 86002 was added at 10(-6) to 10(-4) M concentrations, 0 and 0.5 h prior to endotoxin, and at all concentrations (10(-9) to 10(-4)) when preincubated with macrophages for 2 h.(ABSTRACT TRUNCATED AT 250 WORDS)