BQ-153, a novel endothelin (ET)A antagonist, attenuates the renal vascular effects of endothelin-1

Endothelin (ET)-l, leukotriene D4 and the thromboxane analogue, U-44069, were all shown to produce dose-dependent reductions in renal blood flow after direct injection into the renal artery of anaesthetized pigs. The effects of ET-1 differed from the other two mediators in that ET-1 caused a transient vasodilator followed by a prolonged vasoconstrictor response. The pressor response was not mediated by the secondary release of either leukotriene D4 or thromboxane A2 as evidenced by the lack of effect of appropriate receptor antagonist MK571 (3-{-2(7-chloro-2 quinolinyl) ethenyl}phenyl{3-(dimethylamino-3-oxopropyl)thio}methyl thio propionic acid) and L-670,596 respectively. This response, however, could be inhibited in a dose-dependent fashion by the selective ETA antagonist, BQ-153 (cyclo-d-sulphalanine-l-Pro-d-Val-l-Leu-d-Trp-). Following blockade by BQ-153 the vasodilator response was unaffected and a residual pressor response remained, suggesting that either or both of these effects were mediated either through an ETB or a novel, as yet undefined, endothelin receptor.

Cellular distribution of prostanoid EP receptors mRNA in the rat gastrointestinal tract

The inhibition of PGE(2) synthesis resulting from sustained NSAIDs therapy has been linked to gastrointestinal irritations and ulceration. The multiple physiological effects of PGE(2) in the gut are mediated through the activation of four receptors termed EP(1-4). The aim of the study was to determine the precise distribution of the four prostaglandin E(2) receptors in the rat stomach, small intestine, and colon. We used non-radioactive in situ hybridization techniques on paraffin-embedded tissue. Mucous cells of the stomach and goblet cells of the small intestine and colon were found to express mRNA for all four EP subtypes. A positive hybridization signal for EP(1), EP(3), and EP(4) was detected in the parietal cells of the stomach whereas the chief cells expressed low levels of EP(1) and EP(3). The EP(1) and EP(3) receptor mRNA could also be detected in the muscularis mucosa, longitudinal muscle and enteric ganglias of the stomach and small intestine. However, close examination of the enteric ganglias indicated that most of the positive labeling was localized to the glial cells, although some neurons did express EP(3). In conclusion, we have detailed the distribution of prostanoid EP receptors in the gut at the cellular level, giving new insights to the role of prostaglandins in gastrointestinal functions.

Distribution and regulation of cyclooxygenase-2 in carrageenan-induced inflammation

1 We characterized the regulation of cyclooxygenase-2 (COX-2) at the mRNA, protein and mediator level in two rat models of acute inflammation, carrageenan-induced paw oedema and mechanical hyperalgesia. 2 Carrageenan was injected in the hind paw of rat at low (paw oedema) and high doses (hyperalgesia). COX-2 and prostaglandin E2 (PGE2) levels were measured by RT-PCR and immunological assays. We also determined the distribution of COX-2 by immunohistochemistry. 3 The injection of carrageenan produced a significant and parallel induction of both COX-2 and PGE2. This induction was significantly higher in hyperalgesia than in paw oedema. This was probably due to the 9 fold higher concentration of carrageenan used to provoke hyperalgesia. 4 Immunohistochemical examination showed COX-2 immunoreactivity in the epidermis, skeletal muscle and inflammatory cells of rats experiencing hyperalgesia. In paw oedema however, only the epidermis showed positive COX-2 immunoreactivity. 5 Pretreatment with indomethacin completely abolished the induction of COX-2 in paw oedema but not in hyperalgesia. 6 These results suggest that multiple mechanisms regulate COX-2 induction especially in the more severe model. In carrageenan-induced paw oedema, prostanoid production have been linked through the expression of the COX-2 gene which suggest the presence of a positive feedback loop mechanism.

Differential effect of a selective cyclooxygenase-2 inhibitor versus indomethacin on renal blood flow in conscious volume-depleted dogs

Renal effects of a selective cyclooxygenase-2 (COX-2) inhibitor [MF-Tricyclic; 3-(3,4-difluorophenyl)-4-(4-(methylsulfonyl)phenyl)-2-(5H)-furanone] were studied in control and volume-depleted conscious dogs. MF-Tricyclic was compared with the nonselective COX-1/COX-2 inhibitor indomethacin. Six instrumented male dogs were randomly selected to receive MF-Tricyclic or indomethacin at 10 mg/kg. Volume depletion was effected by a sodium-restricted diet (14 days) with administration of furosemide (7.5 mg/kg, i.v.) the day before the experiment. Indomethacin ablated systemic COX-1 activity (p < 0.05), whereas MF-Tricyclic did not affect this activity. Each compound achieved plasma concentrations in excess of their respective median inhibitory concentrations (IC50 values) against canine COX-2. In controls, neither compound affected mean arterial pressure (MAP), heart rate (HR), renal blood flow (RBF), fractional excretion (FE) Na+, or FE K+. In volume-depleted dogs, indomethacin reduced RBF (p < 0.05), whereas MF-Tricyclic did not affect this parameter. Indices of renal function in volume-depleted dogs were not affected. These data are consistent with the view that the effects of indomethacin on RBF are a consequence of inhibition of COX-1 activity. Furthermore, in these studies, short-term administration of a selective COX-2 inhibitor was without deleterious effects on renal function.

Cardiovascular and renal actions of the endothelin(B) receptor in pigs

Previously we showed that blocking the endothelin (ET)A receptor subtype with BQ-153 inhibited the vasoconstrictor effects of intravenously administered ET-1. In the presence of the ET(A) antagonist, ET-1 produced marked reductions in myocardial contractility and renal blood flow. We postulated that either the ET(B) receptor, or some other, as yet unidentified, ET-receptor subtype mediated the observed hemodynamic changes. In anesthetized pigs, this hypothesis was tested by using a recently developed selective, high-affinity antagonist to the ET(B) receptor, BQ-788, and sarafotoxin S6c, a selective ET(B) agonist, to determine the contribution of this receptor subtype to cardiovascular function. Endothelin-1 (0.4 nmol/kg, i.v.) produced the characteristic biphasic hemodynamic responses, consisting of an initial transient reduction in mean arterial pressure (MAP; 83 +/- 3 to 72 +/- 4 mm Hg; n = 9) followed by a prolonged increase (112 +/- 4 mm Hg; p < 0.01). As well, cardiac output (-58%; p < 0.05), myocardial contractility (-19%; p < 0.01), and renal blood flow (63%; p < 0.05) decreased. Sarafotoxin S6c produced marked but transient reductions in MAP (p < 0.001), cardiac output (p < 0.01), myocardial contractility (p < 0.001), and renal blood flow (p < 0.05). BQ-788 (1.0 mg/kg, i.v.), administered 3 min before sarafotoxin S6c, inhibited its effects. BQ-788 also inhibited the initial transient reduction in MAP seen after the injection of ET-1, but the subsequent sustained pressor responses were enhanced as reflected in the greater increases in left ventricular pressure (p < 0.02), myocardial contractility (p < 0.05), MAP (p < 0.01), and a larger reduction in cardiac output (p < 0.05). The heart rate was not changed after the initial ET injection, but it increased 54% when the peptide was administered in the presence of BQ-788. The reduction in renal blood flow was still evident, and its magnitude (64%) remained the same (p < 0.01) after treatment with BQ-788. Only the combined administration of both the ET(A) (BQ-123) and ET(B) (BQ-788) receptor antagonists blocked the effects of ET-1 on renal blood flow (p < 0.05). These data confirm that BQ-788 is a selective and effective antagonist of the ET(B) receptor and show that activation of this receptor subtype is involved in the transient vasodilation provoked by ET-1. Additionally, the ET(B) receptor appears to oppose the vasoconstrictor effects of the ET(A) receptor, which clearly mediates vasoconstriction. Combined treatment with BQ-123 and BQ-788 attenuated the reductions in renal blood flow produced by ET-1. Furthermore, some actions of ET-1 were not blocked by these antagonists and cannot be attributed to either the ET(A) or ET(B) receptors. We hypothesize the existence of an additional ET receptor or a subtype of the ET(B) receptor that is insensitive to BQ-788.

Dual cardiovascular effects of endothelin-1 dissociated by BQ-153, a novel ETA receptor antagonist

Endothelin-1 (ET-1) is a potent endothelium-derived vasoconstrictor peptide that elicited both vasodilator and vasoconstrictor responses in anesthetized pigs. Within 1.0 min after the first injection of ET-1 (0.4 nmol/kg, intravenously, i.v.) there was a transient decrease in mean arterial pressure (MAP 82 +/- 4 to 64 +/- 5 mm Hg; p < or = 0.01). The vasodepressor response was accompanied by reductions in left ventricular (LV) + dp/dtmax (1,834 +/- 104 to 1,493 +/- 87 mm Hg/s, p < or = 0.001), LV - dp/dt (2,600 +/- 149 to 1,865 +/- 136 mm Hg/s; p < or = 0.001) and cardiac output (CO 2.6 +/- 0.1 to 2.0 +/- 0.1 L/min, p < or = 0.001). The short (< 3.0 min) vasodilatory phase was followed by a prolonged (> 15 min) vasopressor response in which MAP (82 +/- 4 to 103 +/- 5 mm Hg; p < or = 0.001) and pulmonary arterial pressure (PAP 11 +/- 1 to 15 +/- 1 mm Hg; p < or = 0.01) increased. With each subsequent dose (0.4 nmol/kg i.v.) of ET-1, the initial vasodilatory component diminished progressively, only a monophasic vasoconstrictor response was observed after the fourth dose. The reductions in CO progressively decreased from 2.6 to 0.1 to 1.7 +/- 0.1 L/min (p < or = 0.001) by the end of the experiment. In contrast to the systemic circulation effects, ET-1 produced consistent and reproducible reductions in renal blood flow (RBF 105 +/- 16 to 21 +/- 6 mm Hg; p < or = 0.004) that lasted approximately 30 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Application of reversed phase high performance liquid chromatography to the analysis of sulphidopeptide leukotrienes in pig bile

Reversed phase HPLC methodology has been developed for separation of peptide leukotrienes and indomethacin in porcine bile. Reproducible recoveries were obtained using radioactive leukotrienes ([3H]LTC4, 57.1 +/- 2.5%; [3H]LTE4, 62.7 +/- 1.9%; [3H]LTD4, 54.3 +/- 2.7%). Radioimmunoassay of column eluant demonstrated that as little as 300 pg of exogenous leukotrienes could be measured in bile fluids, with similar recoveries. Analysis of bile sampled 60-90 min after initiation of experimental endotoxic shock in indomethacin treated pigs revealed a leukotriene concentration of 5.24 +/- 1.16 ng/mL(LTD4). This was significantly greater (p less than 0.05, n = 3) than that observed in samples collected prior to endotoxin (0.42 +/- 0.23 ng/mL), or from untreated animals (0.85 +/- 0.51 ng/mL). This method is thus applicable to investigation of the role of 5-lipoxygenase products in porcine models of human disease, including shock conditions such as endotoxaemia, during cyclooxygenase inhibition by indomethacin.

Thromboxane A2 and prostaglandin endoperoxide analogue effects on porcine renal blood flow

Thromboxane A2 (TxA2) has been implicated as a mediator of renal and cardiovascular diseases. However, the direct effects of TxA2 on the renal system have been difficult to study because of the instability of the agonist. In the present study injection of synthetic TxA2 directly into the renal artery of anesthetized pigs produced dose-related decreases in renal blood flow (RBF) from 101 +/- 11 to 12 +/- 3 ml/min at the highest dose (20 ng/kg). The reductions in RBF were similar to those produced by the stable prostaglandin endoperoxide analogue, U-44069, although TxA2 was three times more potent. Under these conditions there were no effects on either mean (MAP) or pulmonary arterial pressures (PAP), or the heart rate (HR). The maximal effects produced by TxA2 and U-44069 on RBF were reproducible and the response remained unchanged after pretreatment with either heparin or indomethacin. Systemically administered TxA2 (200 ng/kg iv) increased PAP from 20 +/- 1 to 34 +/- 3 mmHg and this effect was associated with modest increases in MAP and HR. Intravenous administration of the thromboxane receptor antagonist, L-655,240, inhibited the reductions in RBF produced by intrarenal TxA2 and U-44069 and attenuated the cardiopulmonary effects of TxA2 administered intravenously. The results demonstrate directly that TxA2 is a potent agent for decreasing RBF through interaction with a thromboxane receptor.

The pharmacology of L-670,596, a potent and selective thromboxane/prostaglandin endoperoxide receptor antagonist

L-670,596 ((-)6,8-difluoro-9-rho-methylsulfonyl benzyl-1,2,3,4- tetrahydrocarbazol-1-yl-acetic acid) has been shown to be a potent receptor antagonist as evidenced by the inhibition of the binding of 125I-labeled PTA-OH to human platelets (IC50, 5.5 x 10(-9) M), inhibition of U-44069 induced aggregation of human platelet rich plasma (IC50, 1.1 x 10(-7) M), and competitive inhibition of contractions of the guinea pig tracheal chain induced by U-44069 (pA2,9.0). The compound was also active in vivo as shown by inhibition of arachidonic acid and U-44069 induced bronchoconstriction in the guinea pig (ED50 values, 0.04 and 0.03 mg/kg i.v., respectively), U44069 induced renal vasoconstriction in the pig (ED50, 0.02 mg/kg i.v.), and inhibition of ex vivo aggregation of rhesus monkey platelets to U-44069 (active 1-5 mg/kg p.o.). The selectivity of the compound was indicated by the failure to inhibit, first, ADP-induced human or primate platelet aggregation and, second, bronchoconstriction in the guinea pig in vivo and contraction of the guinea pig tracheal chain in vitro to a variety of agonists. It is concluded that L-670,596 is a potent, selective, orally active thromboxane A2/prostaglandin endoperoxide receptor antagonist.

Fractional conversion of thromboxane A2 and B2 to urinary 2,3-dinor-thromboxane B2 and 11-dehydrothromboxane B2 in the cynomolgus monkey

Following the intravenous administration of thromboxane (TX) B2, the stable hydration product of TXA2, to human and nonhuman primates the most abundant urinary metabolites are 2,3-dinor-TXB2 and 11-dehydro-TXB2. However, it is not known whether fractional conversion of TXB2 to its enzymatic metabolites is an accurate representation of TXA2 metabolism. Thus, we have compared the metabolic disposition of synthetic TXA2 and TXB2 via the beta-oxidation and 11-OH-dehydrogenase pathways in vivo in the monkey. TXA2 or TXB2 (20 ng/kg) was intravenously administered to four cynomolgus monkeys pretreated with aspirin in order to suppress endogenous TXA2 production. Urinary TXB2, 2,3-dinor-TXB2 and 11-dehydro-TXB2 were measured before, during and up to 24 h after thromboxane administration by means of reversed-phase high-performance liquid chromatography radioimmunoassay. Aspirin treatment suppressed urinary 2,3-dinor-TXB2 and 11-dehydro-TXB2 by approx. 75%. A similar fractional conversion of TXA2 and TXB2 into 2,3-dinor-TXB2 and 11-dehydro-TXB2 was found. These results suggest that TXA2 is hydrolyzed to TXB2 prior to enzymatic degradation and that metabolites of the latter represent reliable indices of TXA2 biosynthesis. Due to the variability in the conversion of thromboxanes into 2,3-dinor-TXB2 and 11-dehydro-TXB2, the measurement of both metabolites seems to represent a more reliable index of acute changes in TXA2 production.

Interference of the Paf antagonist Ro 19-3704 with Paf and antigen-induced bronchoconstriction in the guinea-pig

1. In vitro, Ro 19-3704, a structurally related antagonist of platelet-activating factor (Paf) inhibited selectively rabbit platelet aggregation. In vivo, administered intravenously, it inhibited bronchoconstriction, leukopenia, thrombocytopenia and the accompanying accumulation of platelet aggregates in guinea-pig lung microvessels induced by i.v. Paf. Administered by aerosol, Ro 19-3704 failed to inhibit bronchoconstriction, thrombocytopenia or leukopenia due to i.v. Paf. 2. Bronchoconstriction induced by Paf, in aerosol form, was blocked by Ro 19-3704 administered by the i.v. or aerosol route, which suggests that it interacts with pulmonary cells responsible for bronchoconstriction. 3. Ro 19-3704 has free radical scavenging properties, since it inhibited the production of superoxide anions by macrophages stimulated by Paf and by N-formyl-methionyl-leucyl-phenylalanine (FMLP). Ro 18-7715, another Paf antagonist and analogue of Ro 19-3704, failed to inhibit the production of superoxide anions by macrophages stimulated by FMLP at concentrations which were effective against Paf. 4. Administered intravenously, Ro 19-3704 failed to block bronchoconstriction induced by an i.v. injection of ovalbumin to guinea-pigs passively sensitized with anti-ovalbumin antiserum. Passive pulmonary anaphylaxis due to an aerosol of ovalbumin was blocked by i.v. Ro 19-3704.

Involvement of PAF-acether in anaphylactic bronchoconstriction induced in guinea pigs by aerosolized antigen

Bronchoconstriction following the aerosolization of PAF-acether or antigen to guinea pigs induces autodesensitization, but the responses to direct spasmogenic substances are not modified. Bronchoconstriction by PAF-acether is not reduced when it is aerosolized to passively sensitized animals previously desensitized by repeated inhalations of the allergen (ovalbumin). In contrast, when passively sensitized animals are initially desensitized to PAF-acether by repeated inhalations of this agonist, ovalbumin aerosolization induces a bronchoconstriction which is significantly reduced when compared with the response obtained in nondesensitized animals though, in this case, the response to aerosolized histamine is not modified. Thus, PAF-acether is released during intrapulmonary anaphylactic shock induced by aerosolized ovalbumin and can be a prime candidate for its development.

Biliary and urinary excretion of peptide leukotrienes in the domestic pig

The metabolism of leukotriene (LT)C4 and its major routes of elimination in vivo have been studied in four anesthetized domestic pigs administered intravenous [3H]-LTC4 (0.5 microCi/kg). The kinetic profile of LTC4 in the blood was followed for 60 min after administration while the biliary and urinary excretion of LTC4 and its metabolites were determined over a 120 min interval. The total recovery of radioactivity in bile and urine was 45% +/- 1 (n = 3) and 18% (n = 2) respectively. Examination of the radioactive metabolites in bile showed LTD4 (44% of biliary content) and LTE4 (21% of biliary content) as the major identified lipoxygenase products at t 1/2 (27 min). The only identified cysteinyl leukotriene observed in the urine was LTE4 (13% of urinary content). In both bile and urine substantial amounts of radioactivity were detected at the solvent front of the reverse phase chromatographic system indicating the presence of additional unidentified metabolites. We suggest that measurement of metabolites using these sampling methods may be useful for the detection and measurement of peptide leukotriene production in vivo.

Interference of the PAF-acether antagonist BN 52021 with passive anaphylaxis in the guinea-pig

PAF-acether may be involved in anaphylaxis and asthma. We tested the new PAF-acether antagonist BN 52021 against the effects of antigen in passively sensitized guinea-pigs. Bronchoconstriction by ovalbumin administered i.v. (1 mg/kg) or by aerosol (1 or 10 mg/ml for a period of 1 min) was significantly reduced by BN 52021 (1-10 mg/kg), which did not inhibit drop of leukocyte counts after the i.v. challenge. In both cases, when the guinea-pigs were pretreated by propranolol, high amounts of BN 52021 became ineffective against shock. The reduction of the anaphylactic bronchoconstriction, induced by the combination of mepyramine, aspirin and FPL 55712 was not improved by BN 52021. Tested on isolated lung strips from passively sensitized guinea-pig, BN 52021, at a concentration which inhibits PAF-induced contraction (0.1 mM), did not inhibit the anaphylactic contraction triggered by the administration of ovalbumin (10 micrograms/ml) nor the accompanying release of histamine and thromboxane. In contrast, BN 52021 (30 microM) significantly reduced the anaphylactic release of histamine and of thromboxane from perfused lungs of passively sensitized guinea-pigs. The results with the isolated lung strips and the propranolol-treated guinea-pigs in vivo suggest a dissociation between the anti-anaphylactic and the anti-PAF-acether properties of BN 52021.

A study with BN 52021 demonstrates the involvement of PAF-acether in IgE-dependent anaphylactic bronchoconstriction

The involvement of platelet activating factor (PAF) in anaphylaxis was examined by recording the pulmonary responses of anesthetized passively sensitized guinea-pigs to the aerosolization of ovalbumin. Animals were tested with and without BN 52021 (a ginkgolide B, PAF receptor antagonist) pretreatment. Aerosolization of ovalbumin produced a bronchoconstriction (BC) which could be made refractory to additional challenges with the antigen. In animals desensitized to ovalbumin, aerosolization of PAF produced an unattenuated BC. Guinea pigs desensitized by repeated aerosolizations of PAF subsequently showed reduced responses to aerosolized antigen suggesting that PAF may be involved in the BC. Animals pretreated with BN 52021, were protected against the effects of systemically administered PAF and also showed reduced responses to aerosolized antigen. Aerosolization of the leukotriene antagonist, FPL 55712, was ineffective against anaphylactic BC under conditions where catecholamine and histamine release were blocked.

Actions of synthetic leukotrienes on platelets and blood vessels in the anesthetised pig: the release of a platelet derived vasodilator

The actions of leukotrienes (LT's) C4, D4, E4 and F4 have been investigated in the perfused hind-limb of the anesthetized pig. In the blood perfused hind limb LTC4, D4 and E4 increased the perfusion pressure in a dose-dependent fashion whereas LTF4 decreased perfusion pressure. In the Tyrode perfused hind limb all LT's increased perfusion pressure (rank order potency LTC4 = LTD4 much greater than LTF4). The actions of LTF4 were not affected by a wide variety of pharmacological treatments, including indomethacin, methysergide and FPL-55712. The LT's aggregated porcine platelets (rank order potency LTC4 greater than LTF4 greater than LTD4) and induced the release of a platelet-derived vasodilatory mediator. The results provide pharmacological evidence of specific leukotriene receptors in vivo and that leukotrienes can independently modulate blood flow. These data suggest that important interactions may occur between platelets, the arachidonate lipoxygenase products and platelet-derived substances in response to inflammatory stimuli in the cardiovascular system.

Influence of lateral septum and amygdala stimulation on the excitability of hypothalamic supraoptic neurons. An electrophysiological study in the rat

Extracellular recordings were obtained from 116 phasically-active (putative vasopressinergic) and 113 continuously-active (putative oxytocinergic) neurosecretory neurons in the hypothalamic supraoptic nucleus of urethane or pentobarbital anesthetized male Sprague-Dawley rats. Single 1 Hz pulse stimulation in most regions of the amygdala and the ipsilateral lateral septum was followed by a transient (20-140 ms) reduction in the excitability of more than 90% of responsive cells; one third displayed a reduction in excitability to both amygdala and lateral septum stimulation. Amygdala or lateral septum stimuli delivered in brief trains of 20-100 pulses at 5-20 Hz during ongoing phasic discharges could induce silent periods lasting up to 30 or more seconds beyond the time of application. The same stimuli also reduced ongoing activity among continuously-firing SON cells but their response lasted only as long as the duration of the applied stimulus. These data suggest that neurons in both the ipsilateral septum and the various amygdaloid nuclei exert a predominantly inhibitory influence on the excitability of both vasopressinergic and oxytocinergic SON neurons in the rat.

Bronchoconstriction induced by N-formyl-methionyl-leucyl-phenylalanine in the guinea pig; involvement of arachidonic acid metabolites

The chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (F-met-leu-phe) was shown to be a potent myotropic agent on the guinea-pig parenchymal strip (IC50, 2 X 10(-7)M). The response was unaffected by the histamine (H1) antagonist, mepyramine, but in the presence of the cyclooxygenase inhibitor, indomethacin, the dose response curve was shifted to the left (IC50, 4 X 10(-8)M) and the maximal response reduced. Injection of F-met-leu-phe into perfused guinea pig lungs resulted in the release of leukotriene-like activity which was detected by superfusion over guinea-pig ileum preparations in the presence and absence of FPL-55712. Intravenous injection of F-met-leu-phe to spontaneously breathing anaesthetized guinea pigs resulted in transient increases in pulmonary resistance and blood pressure and decreases in dynamic compliance and heart rate. The pulmonary parameters were significantly inhibited by BW 755C, indomethacin, FPL-55712 and a contractile prostanoid antagonist, L-640,035. These results demonstrate that F-met-leu-phe is a potent bronchoconstrictor in the guinea pig and that the peptide may induce these changes through the generation of products of the cyclooxygenase and lipoxygenase pathways of arachidonic acid metabolism.

Synthesis and biological activities of leukotriene F4 and leukotriene F4 sulfone

Leukotriene F4 (LTF4) and LTF4 sulfone have been synthesized and their biological activities determined in the guinea pig. In vitro LTF4 displayed comparable activity to LTD4 on guinea pig trachea and parenchyma but was less active on the ileum. When injected intravenously into the guinea pig, LTF4 induced a bronchoconstriction (ED50 16 micrograms Kg-1) which was blocked by indomethacin and FPL-55712 and was 50-100 X less potent than LTD4 in this assay. LTF4 sulfone was approximately 2-5 times less active than LTF4 in vitro and in vivo. When injected into guinea pig skin with PGE2 (100 ng); LTF4 and LTF4 sulfone (10-1000 ng) induced changes in vascular permeability. The order of potency in this assay was LTE4 sulfone = LTD4 = LTD4 sulfone greater than LTE4 greater than LTF4 = LTF4 sulfone.