Effect of FK3657, a non-peptide bradykinin B2 receptor antagonist,on allergic airway disease models

Bradykinin has been suggested to be involved in allergic diseases. In this study, we tested the effect of FK3657 ((E)-3-(6-acetamido-3-pyridyl)-N-[N-[2,4-dichloro-3-[(2-methyl-8-quinolinyl)-oxymethyl]phenyl]-N-methylaminocarbonylmethyl]acrylamide), an orally active non-peptide bradykinin B(2) receptor antagonist, on allergic airway disease models in guinea pigs. FK3657 given orally inhibited bradykinin-induced or dextran sulfate (an activator of kinin-kallikrein cascade)-induced bronchoconstriction and plasma extravasation in the lower airways (trachea and main bronchi) and nasal mucosa of guinea pigs with ED(50) of 0.04-0.23 mg/kg. In the antigen-induced dual asthmatic response model of guinea pigs, FK3657 significantly attenuated the late phase asthmatic response, but not the immediate asthmatic response. FK3657 also significantly inhibited the 2,4-tolylene diisocyanate (TDI)-induced plasma extravasation in nasal mucosa of TDI-sensitized guinea pigs. These results suggest that oral FK3657 may be useful for asthma or allergic rhinitis as a therapeutic drug.     

Neurogenic plasma leakage in mouse airways

1. This study sought to determine whether neurogenic inflammation occurs in the airways by examining the effects of capsaicin or substance P on microvascular plasma leakage in the trachea and lungs of male pathogen-free C57BL/6 mice. 2. Single bolus intravenous injections of capsaicin (0.5 and 1 micromol kg(-1), i.v.) or substance P (1, 10 and 37 nmol kg(-10, i.v.) failed to induce significant leakage in the trachea, assessed as extravasation of Evans blue dye, but did induce leakage in the urinary bladder and skin. 3. Pretreatment with captopril (2.5 mg kg(-1), i.v.), a selective inhibitor of angiotensin converting enzyme (ACE), either alone or in combination with phosphoramidon (2.5 mg kg(-1), i.v.), a selective inhibitor of neutral endopeptidase (NEP), increased baseline leakage of Evans blue in the absence of any exogenous inflammatory mediator. The increase was reversed by the bradykinin B2 receptor antagonist Hoe 140 (0.1 mg kg(-1), i.v.). 4. After pretreatment with phosphoramidon and captopril, capsaicin increased the Evans blue leakage above the baseline in the trachea, but not in the lung. This increase was reversed by the tachykinin (NK1) receptor antagonist SR 140333 (0.7 mg kg(-1), i.v.), but not by the NK2 receptor antagonist SR 48968 (1 mg kg(-1), i.v.). 5. Experiments using Monastral blue pigment as a tracer localized the leakage to postcapillary venules in the trachea and intrapulmonary bronchi, although the labelled vessels were less numerous in mice than in comparably treated rats. Blood vessels of the pulmonary circulation were not labelled. 6. We conclude that neurogenic inflammation can occur in airways of pathogen-free mice, but only after the inhibition of enzymes that normally degrade inflammatory peptides. Neurogenic inflammation does not involve the pulmonary microvasculature.     

Proinflammatory characteristics of a nonpeptide bradykinin mimic, FR190997, in vivo

1. Proinflammatory potency of the nonpeptide bradykinin (BK) B(2) receptor agonist FR190997 (8-[2,6-dichloro-3-[N-[(E)-4-(N-methylcarbamoyl)cinnamidoacetyl]-N-methylamino]benzyloxy]-2-methyl-4-(2-pyridylmethoxy)quinoline) was investigated. 2. Intradermal injection of FR190997 (0.03 - 3 nmol site(-1)) into dorsal skin of rats increased vascular permeability in a dose-dependent manner. The effect was less than that of BK, but it was long-acting and was inhibited by treatment with FR173657 (3 mg kg(-1), p.o.). Captopril (10 mg kg(-1), i.p.) did not enhance the plasma extravasation by FR190997 (0.3 nmol site(-1)) in the presence of soybean trypsin inhibitor (SBTI, 30 microg site(-1)). 3. Subcutaneous injection of FR190997 (3 nmol site(-1)) into the hindpaw of mice markedly induced paw swelling. The oedema lasted up to 3 h after the injection. Administration of indomethacin or NS-398 (10 mg kg(-1), i.p.) significantly reduced it at 3 h after the injection. 4. Simultaneous i.p. injection of prostaglandin (PG) E(2) (1 nmol site(-1)) or beraprost sodium (0.5 nmol site(-1)) with FR190997 (5 nmol site(-1)) greatly enhanced frequency of writhing reactions in mice. 5. FR190997 (0.3 - 30 nmol kg(-1), i.v.) showed less increase in airway opening pressure (Pao) in the guinea-pig after i.v. injection. Furthermore, FR190997 (0.03 - 30 nmol) resulted in a very weak contraction of tracheal ring strips and lung parenchymal sections in vitro. 6. In mice sponge implants, topical application of FR190997 increased angiogenesis and granulation with enhanced expressions of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) mRNAs. 7. These results indicate that FR190997 has proinflammatory long-lasting characteristics and it might be 'a stable tool' for studying the role of BK B(2) receptor in vivo.     

Characterization of non-peptide bradykinin B2 receptor agonist (FR 190997) and antagonist (FR 173657)

Pharmacologic parameters for a novel non-peptide bradykinin (BK)-B2 receptor agonist, 8-[2,6-dichloro-3-[N-[(E)-4-(N-methylcarbamoylcinnamidoacetyl]-N-+ ++methylano] benzyloxy]-2-methyl-4-(2-pyridylmethoxy)quinoline (FR 190997) (pEC50, ED50 values) and for the antagonist (E)-3-(6-acetamido-3-pyridyl)-[N-[2,4-dichloro-3-[(2-methyl-8-quinolinyl ) oxymethyl] phenyl]-N-methylaminocarbonylmethyl] acrylamide (FR 173657) (pIC50, ID50 values) were measured using conventional contractile B2 receptor bioassays from rabbit, guinea pig and rat tissues and by mean of animal blood pressure models performed on anesthetized animals in the same species. In vitro assays (on the rabbit jugular vein and the guinea pig ileum) demonstrated that both the onset and duration of action of FR 190997 are prolonged compared to BK. These in vitro effects of FR 190997 strongly desensitized upon repeated tissue applications. Similar pEC50 values (7.7) were measured on the rabbit and the guinea pig tissues. In vivo, when injected intraarterially, FR 190997 produced hypotensive responses in rabbits and guinea pigs with ED50 values of 3.7 +/- 0.5 and 8.9 +/- 3.6 nmol/kg, respectively. Both the contractile and the hypotensive effects of FR 190997 were abolished by pretreating tissues (1 microM) or animals (0.1-0.5 micromol/kg) with D-Arg-[Hyp3,Thi5,D-Tic7,Oic8]BK (HOE 140) or FR 173657. FR 173657 (pIC550 approximately 8.40), as well as other known antagonists (e.g., HOE 140, D-Arg-[Hyp3,D-Phe7,Leu8]BK), inhibited the in vitro myotropic effects of BK on the rabbit, guinea pig and rat tissues. FR 173657 also abrogated the in vivo hypotensive responses elicited by BK in the rabbit (ID50 57 +/- 9 nmol/kg), the guinea pig (ID50 215 +/- 56 nmol/kg) and the rat (ID50 187 +/- 50 nmol/kg). The in vivo duration of action of FR 173657 was significantly lower in the rabbit (= 20 min) than in the guinea pig and the rat (> 90 min). It is concluded that the non-peptides FR 190997 and FR 173657 enable efficient activation and antagonism of rabbit and guinea pig B2 receptors. These non-peptide molecules represent a marked progress in medicinal chemistry and may be useful to define the role played by the kallikrein/kinin system in vivo.     

A potential role of bradykinin in angiogenesis and growth of S-180 mouse tumors

Angiogenesis is an important event in tumor growth. We evaluated the contribution of endogenous bradykinin to tumor-associated angiogenesis and tumor growth using pharmacological approaches in mice bearing sarcoma 180 cells. The weight of implanted tumors increased in parallel with increased hemoglobin contents (a parameter to evaluate angiogenesis) over a 20-day experimental period. Daily administration of bradykinin B2-receptor antagonists, Hoe140 (0.1 and 1 mg/kg per day, local injection) or FR173657 (30 mg/kg per day, p.o.), significantly suppressed the increment in angiogenesis and tumor weight, but a B1-receptor antagonist, desArg10-Hoe140 (1 mg/kgperday), did not. Administration of a plasma kallikrein inhibitor, soybean trypsin inhibitor (3 mg/site per day), significantly suppressed angiogenesis and tumor growth. In contrast, bradykinin-degrading enzyme inhibitors, captopril and phosphoramidon (500 microg/site per day), enhanced angiogenesis and increased tumor weight. Our results suggest that bradykinin, produced by plasma kallikrein or plasma kallikrein-like enzymes, promote tumor-associated angiogenesis and tumor growth in vivo.     

速激肽受体拮抗剂抗豚鼠过敏性哮喘的作用

实验目的是研究速激肽与哮喘的关系,评价速激肽受体拮抗剂对哮喘的治疗作用。结果表明,ip速激肽NK-1受体拮抗剂CP-96345,NK- 2受体拮抗剂SR-48968或两药合用,均可有效减少清醒致敏豚鼠吸入抗原引起的喘息反应,降低过敏性休克死亡率。SR-48968减轻麻醉豚鼠抗原引起的气道收缩,并浓度依赖性降低抗原引起的气管和支气管平滑肌收缩幅度。CP-96345可抑制抗原诱导的支气管和肺叶伊文思蓝渗出,仅对支气管平滑肌收缩有部分抑制作用。结果提示,速激肽参与哮喘发病,速激肽受体拮抗剂可抑制抗原诱导的气道平滑肌收缩(NK-2受体)和微血管渗漏(NK-1受体)而减轻哮喘反应。     

BradykMn-induced airway microvasciilar leakage is potentiated by captopril and phosphoramidon

Bradykinin can be inactivated by the peptidases angiotensin-converting enzyme (ACE) and neutral endopeptidase (NEP), both of which are present in the airways. We evaluated the role of these enzymes in bradykinin-induced airway microvascular leakage and lung resistance in anesthetized and mechanically ventilated guinea pigs. We studied the effects of captopril (inhaled; 350 nmol), a specific ACE inhibitor, and phosphoramidon (inhaled; 7.5 nmol), a specific NEP inhibitor. Airway microvascular leakage was measured with the albumin marker Evans Blue dye (20 mg/kg i.v.), and airflow obstruction was measured as lung resistance (R_L). Bradykinin was given by inhalation (0.1, 0.3 and 1 mM; 45 breaths), and caused a dose-dependent increase in both R_L and airway microvascular leakage. Inhibition of NEP or ACE potentiated the bradykinin-induced microvascular leakage in main bronchi and proximal and distal intrapulmonary airways. However, only NEP inhibition significantly potentiated the extravasation of Evans Blue dye into the tracheal wall and lumen. The combined inhibition of NEP and ACE significantly potentiated plasma leakage at all airway levels, as well as the increase in R_L induced by inhaled bradykinin. Recovery R_L after one lung inflation significantly correlated with the extravasation of Evans Blue dye in the tissue at all airway levels, indicating that airway edema may have contributed to airway narrowing. We conclude that in the guinea pig, both NEP and ACE modulate bradykinin-induced airway microvascular leakage.     

Effects of FR 113680 and FK 224, novel tachykinin receptor antagonists, on cigarette smoke-induced rat tracheal plasma extravasation.

We examined the effects of novel tachykinin antagonists, FR 113680 (N alpha-[N alpha-(N alpha-acetyl-L-threonyl)-N1-formyl-D-tryptophyl]-N- methyl-N-phenylmethyl-L-phenylalaninamide) and FK 224 (N-[N2-[N-[N-[N-[2,3-didehydro-N-methyl-N-[N[3-(2-phenthylpheny l) - propionyl]-L-threonyl]-tyrosyl]-L-leucynyl]-D-phenylalanyl]-L-allo - threonyl]-L-asparaginyl]-L-serine nu-lactone) on rat tracheal plasma extravasation induced by cigarette smoke. Intravenous injection of FK 224 (0.032-3.2 mg kg-1) inhibited rat tracheal plasma extravasation induced by cigarette smoke and capsaicin. FR 113680 (32 mg kg-1 i.v.) also significantly inhibited cigarette smoke-induced plasma extravasation, whereas D-chlorpheniramine maleate, FPL 55712, atropine sulfate and indomethacin had no effect. Tracheal plasma extravasation induced by substance P (SP) and neurokinin A (NKA), but not histamine, was also reduced by intravenous administration of FR 113680 and FK 224. These findings suggest that cigarette smoke stimulates primary afferent sensory nerves, releases tachykinins and evokes plasma extravasation in rat trachea.     

Suppression of the Arthus reaction by Y-24180, a potent and specific antagonist of platelet-activating factor.

A novel and potent antagonist of platelet-activating factor (PAF), Y-24180 (4-(2-chlorophenyl)-2-[2-(4-isobutylphenyl)ethyl]-6,9-dimethyl-6H- thieno[3,2-f][1,2,4]triazolo[4,3-a][1,4] diazepine) was investigated for the effects on the skin reactions induced by chemical mediators and the Arthus reactions. In the rat dorsal skin, Y-24180 (0.1-10 mg/kg, p.o.) inhibited increase in vascular permeability by the intradermal PAF injection in a dose dependent manner and the inhibitory activity was 60 times more potent than that of WEB 2086. While even at doses as large as 10 mg/kg, p.o., it had no effect on vascular permeability in the rat skin induced by histamine, serotonin, bradykinin and leukotriene D4. On a reversed passive Arthus reaction in rat dorsal skin, Y-24180 (0.1-1 mg/kg, p.o.) markedly inhibited vascular permeability in a dose dependent manner and the inhibitory activity was 15 times more potent than that of WEB 2086. Y-24180 also inhibited the Arthus dermal reaction in rabbits (0.03-0.3 mg/kg, p.o.) and guinea pigs (0.1-1 mg/kg, p.o.). In addition, Y-24180 (0.1-10 mg/kg, p.o.) significantly reduced the exudate volume and the number of infiltrated inflammatory cells in the reversed passive Arthus pleural reaction in rats. Furthermore, in rat passive Arthus pancreatitis, Y-24180 (0.3-10 mg/kg, p.o.) significantly inhibited the dye extravasation from the pancreas. These results provide strong evidence that endogenous PAF plays an important role as a mediator in the type III allergic inflammation.     

Effect of BW443C81, a novel opioid, on non-cholinergic bronchoconstrictor responses and neurogenic plasma extravasation in the guinea pig.

The novel, peripherally acting opioid peptide, BW443C81, which attenuates airway sensory nerve impulses, was examined on non-cholinergic (NC) constrictor responses in vitro and in vivo and neurogenic plasma extravasation in vivo in guinea-pig airways. Non-cholinergic contractions of guinea pig isolated bronchi, evoked by electrical field stimulation, were concentration-dependently inhibited by BW443C81 and morphine (10 nmol/1-100 mumol/l). In anaesthetised, artificially ventilated guinea pigs, frequency-related NC bronchoconstrictor responses evoked by antidromic electrical stimulation of the vagus nerves were reduced by BW443C81 (100 micrograms/kg/min i.v. infusion) and morphine (1 mg/kg i.v.). Neurogenic plasma extravasation produced by bilateral electrical vagal nerve stimulation in spontaneously breathing, anaesthetised guinea pigs was also inhibited by BW443C81 (1 mg/kg i.v.). The inhibitory effects of BW443C81 were reversed/prevented by naloxone. BW443C81 inhibits NC bronchoconstrictor responses and neurogenic plasma extravasation in guinea pig airways, consistent with its previously described mu-opioid receptor-mediated inhibitory action on airway sensory nerve function.     

Lack of a role for bradykinin in inhaled sodium metabisulphite-induced airway microvascular leakage in guinea pigs

We have investigated the role of bradykinin in airway microvascular leakage and bronchoconstriction induced by inhaled sodium metabisulphite (MBS) in guinea pigs. A selective bradykinin B2 receptor antagonist, HOE 140 (D-Arg[Hyp³, Thi⁵, D-Tic⁷, Oic⁸]-bradykinin), was used because this drug has been shown to abolish the airway responses induced by bradykinin. Lung resistance (R_L) was measured for 6 min after challenge with MBS, followed by measurement of extravasation of Evans Blue dye into airway tissues, used as an index of plasma exudation. Aerosolized MBS (40 and 80 mmol/L, 30 breaths) induced a significant increase in R_L and leakage of dye in the trachea, main bronchi and intrapulmonary airways, whereas 20 mmol/L MBS caused these responses except for the dye leakage in the trachea and main bronchi. HOE 140 (100 nmol/kg iv) had no effect against these airway responses. We conclude that bradykinin-mediated mechanisms do not play a significant role in the acute airway effects induced by inhaled MBS.     

Peptide and non-peptide bradykinin B2 receptor agonists and antagonists: a reappraisal of their pharmacology in the guinea-pig ileum

We have compared the pharmacology of different antagonists, Icatibant (H-DArg-Arg-Pro-Hyp-Gly-Thi-Ser-DTic-Oic-Arg-OH), MEN 11270 (H-DArg-Arg-Pro-Hyp-Gly-Thi-c(Dab-DTic-Oic-Arg)c(7 gamma-10 alpha)), and FR173657 ((E)-3-(6-acetamido-3-pyridyl)-N-[N-[2, 4-dichloro-3-[(2-methyl-8-quinolinyl)oxymethyl]phenyl]-N-methyl aminocarbonylmethyl]acrylamide) at bradykinin B2 receptors expressed in the guinea-pig ileum by using bradykinin and the non-peptide FR190997 ((8-[2,6-dichloro-3-[N-[(E)-4-(N-methylcarbamoyl)cinnamidoacety l]-N -methylamino]benzyloxy]-2-methyl-4-(2-pyridylmethoxy)quinoline) as agonists. In organ bath experiments, Icatibant and FR173657 exerted a non-competitive antagonism (pKB 9.5 and 9.2, respectively) of the contractile response to bradykinin, whereas MEN 11270 showed competitive antagonism (pKB 8.3, slope -0.90). The profile of action and apparent affinities of the three antagonists did not change if contact time was prolonged. The inhibition by the three antagonists of the contractile response to bradykinin was differently reverted by washout (MEN 11270 <30 min, Icatibant <60 min, FR173657 >60 min). The non-peptide ligand FR190997 acted as partial agonist if applied cumulatively to the bath (pD2 8.06, Emax 43% of maximal contractility), but as a full agonist when a maximally effective concentration was added (Emax 83%). FR173657 produced non-competitive antagonism of the response to FR190997 with apparent affinity similar to that measured toward bradykinin. On the contrary, Icatibant and MEN 11270 (300 nM both) competitively antagonized the contractile activity exerted by FR190997 with lower apparent pA2 value (6.9 and 7.2, respectively). In radioligand binding experiments, MEN 11270 and Icatibant displaced the [3H]bradykinin binding with pKi of 10.2 and 10.5 (Hill slope not different from unity), respectively. The non-peptide ligands displaced the [3H]bradykinin binding with similar affinity, their pKi being 8.7 and 8.6 for FR173657 and FR190997, respectively (both Hill slopes <1). The present study indicates the difference in the antagonism type (competitive vs. non-competitive) by Icatibant, MEN 11270, and FR173657, as mainly ascribable to their different reversibility from the bradykinin B2 receptor, and affected by the kinetic of the response induced by the different agonists. Results are discussed in view of a different interaction of peptide and non-peptide agonist at the receptor.     

Nociceptin inhibits airway microvascular leakage induced by HCl intra-oesophageal instillation

1. Gastro-oesophageal acid reflux may cause airway responses such as cough, bronchoconstriction and inflammation in asthmatic patients. Our previous results suggest that microvascular leakage induced, in the guinea-pig airways, by intra-oesophageal hydrochloric acid (HCl) infusion was mainly dependent on the release of tachykinins. Nociceptin, an endogenous ligand of the opioid receptor NOP, has been shown to inhibit bronchoconstriction and cough in guinea-pig or cat by inhibiting tachykinin release. 2. The purpose of this study was to investigate the effects of nociceptin on the intra-oesophageal HCl-induced airway microvascular leakage evaluated by Evans blue dye extravasation measurement in anaesthetised guinea-pigs pretreated with propranolol, atropine and phosphoramidon. 3. Infusion of intra-oesophageal HCl led to a significant increase in plasma extravasation in the main bronchi and trachea. This increase was abolished when animals underwent a bilateral vagotomy. 4. Airway microvascular leakage was inhibited by nociceptin (3-30 microg x kg(-1) i.v.) in a dose-dependent manner (maximal inhibition at the dose of 30 microg x kg(-1): 19.76+/-1.13 vs 90.92+/-14.00 ng x mg(-1) tissue for nociceptin and HCl infusion, respectively, in the main bronchi, P<0.01). The NOP receptor agonist [Arg(14),Lys(15)]N/OFQ mimicked the inhibitory effect of nociceptin, but at a 10-fold lower dose (3 microg x kg(-1) i.v). The NOP receptor antagonist J-113397 had no effect on plasma protein extravasation by itself, but was able to block the inhibitory effect of nociceptin. 5. Morphine (1 mg x kg(-1)) had a similar inhibitory effect as that of nociceptin. Naloxone pretreatment abolished the effect of morphine, but was enable to block the inhibitory effect of nociceptin. 6. Under similar conditions, nociceptin, in the previous range of concentration, was unable to counteract the airway microvascular leakage induced by substance P (SP). 7. These results suggest that airway plasma extravasation induced by intra-oesophageal HCl instillation might be inhibited by specific stimulation of the NOP receptor with nociceptin. Nociceptin is likely to act at a pre-junctional level, by inhibiting tachykinin release, since it was unable to prevent SP-induced airway plasma extravasation.     

Effects of the new antiallergic drug 11-oxo-11H-pyrido[2,1-b] quinazoline-2-carboxylic acid on type I allergic reactions

Antiallergic effects of the newly synthesized, quinazoline derivative 11-oxo-11H-pyrido[2,1-b]quinazoline-2-carboxylic acid (Sm 857) were investigated. The following results were obtained. 1. Anaphylactic and non-immunologic histamine and slow reacting substance of anaphylaxis (SRS-A) release from guinea pig lung fragments was dose-dependently inhibited by 10(-6)-10(-4) and 10(-7) -10(-4) g/ml of Sm 857, respectively. Similar inhibition of the mediator release by the compound was obtained from the experiments of passively sensitized monkey and human lung fragments by antigen. 2. Seven-day passive cutaneous anaphylaxis of guinea pigs was not inhibited at 1-20 mg/kg (i.v.) of Sm 857, but inhibited at 20-100 mg/kg (p.o.) in some experiments without dose dependency. 3. Cutaneous anaphylaxis and histamine-induced cutaneous reaction in guinea pigs were hardly affected by the treatment of 50 and 100 mg/kg (p.o.) of Sm 857. 4. Passive systemic anaphylaxis in guinea pigs was not inhibited at 50-200 mg/kg (p.o.) of Sm 857. 5. Arthus reaction in rabbits was slightly and dose-dependently enhanced at 50-200 mg/kg given twice p.o. 6. Sm 857 (10(-6)-10(-4) g/ml) exhibited antispasmogenic activity against histamine and leukotriene D4 in isolated human bronchi and guinea pig trachea, however, this activity is attributable to non-specific musculotropic smooth muscle relaxation. From these results it may be concluded that Sm 857 exerts preferential effect on the respiratory system and that it might be useful in allergic asthma.     

Effect of alacepril on renin-angiotensin-aldosterone system and kallikrein-kinin-prostaglandin system in experimental animals

The effects of 1-[(S)-3-acetylthio-2-methylpropanoyl]-L-prolyl-L-phenylalanine (alacepril, DU-1219), an orally active angiotensin converting enzyme (ACE) inhibitor, on humoral factors which participated in the blood pressure control were examined with various experimental animals. In conscious renal hypertensive dogs, alacepril (3 mg/kg p.o.) showed decreases in plasma ACE activity and plasma aldosterone concentration, and increases in plasma renin activity and plasma angiotensin I concentration accompanied by a significant reduction in blood pressure. In conscious normotensive dogs, alacepril (1 and 3 mg/kg p.o.) showed an increase in urinary excretion of bradykinin accompanied by increases in urinary water and sodium excretion. In spontaneously hypertensive rats, alacepril (30 and 100 mg/kg p.o.) showed increases in urinary excretion of bradykinin and 6-keto-prostaglandin Fl alpha, and a decrease in that of aldosterone accompanied by increased in excretion of water and sodium. These results indicate that the antihypertensive activity of alacepril is due to the suppression of renin-angiotensin-aldosterone system and the enhancement of kallikrein-kinin-prostaglandin system through the inhibition of ACE (kininase II) activity in vivo.     

Effect of Hoe 140, a new bradykinin receptor antagonist, on bradykinin- and platelet-activating factor-induced bronchoconstriction and airway microvascular leakage in guinea pig.

We have investigated the effect of a new bradykinin receptor antagonist, Hoe 140 (D-Arg- Hyp3,Thi5,D-Tic7,Oic8]-bradykinin), on bradykinin- and platelet-activating factor (PAF)-induced bronchoconstriction and airway microvascular leakage in anesthetized guinea pigs. Extravasation of Evans blue dye and lung resistance were measured simultaneously. Both i.v. (15 nmol/kg) and inhaled bradykinin (1 mM, 45 breaths) caused a significant increase in lung resistance and leakage of dye at all airway levels. Hoe 140 (100 nmol/kg i.v.) almost completely inhibited these airway responses induced by bradykinin except for dye extravasation in trachea induced by inhaled bradykinin. Inhaled PAF (3 mM, 30 breaths) significantly increased lung resistance and leakage of due at all airway levels, but Hoe 140 had no effect on these responses. Bradykinin-induced bronchoconstriction and airway microvascular leakage are predominantly mediated by activation of B2 receptor, since Hoe 140 is a B2 receptor antagonist. Bradykinin receptor-mediated mechanisms do not play an important role on inhaled PAF-induced bronchoconstriction and microvascular leakage.     

Role of kinin and prostaglandin in cutaneous thermal nociception

Involvements of kinin and prostaglandin and their interaction in noxious thermal stimuli were investigated in noninflamed and inflamed rats. The nociceptive response was evaluated from the escape latency of foot withdrawal to the thermal stimuli with a beam of light. The escape latency in kininogens-deficient Brown Norway (B/N-) Katholiek rats was significantly longer than that in the normal strain, B/N-Kitasato rats. The latency in B/N-Kitasato rat was prolonged by administration of a bradykinin (BK) B2 receptor antagonist, FR173657 (30 mg/kg, p.o.), whereas it was shortened by pretreatment with a kininase II inhibitor, captopril (10 mg/kg, i.p.). Both agents did not affect the latency in B/N-Katholiek rats. In normal Sprague-Dawley (SD) rat, administration of indomethacin did not change the escape latency against the thermal stimuli. In contrast, administration of indomethacin or a relatively cyclooxygenase-1-selective inhibitor, mofezolac (10 mg/kg, p.o.) significantly reduced numbers of writhing reaction in mice induced by acetic acid solution. Injection of lipopolysaccharide (1 mg/kg, i.v.) resulted in shortening escape latency at 8 h after the injection in B/N-Kitasato rats. This hyperalgesia could be reversed by pretreatment of the rats with indomethacin, a cyclooxygenase-2-selective inhibitor JTE-522 (10 mg/kg, p.o.), or FR173657, but not with mofezolac. The hyperalgesia was not seen in B/N-Katholiek rats. These results indicate that kinin has major participation in peripheral skin thermal nociception under noninflamed condition, although cyclooxygenases may have little participation. Prostaglandins produced by cyclooxygenase-2 could coordinate with BK to elicit hyperalgesia during inflammation induced by lipopolysaccharide.     

Endogenous bradykinin suppresses myocardial fibrosis through the cardiac-generated endothelin system under chronic angiotensin-converting enzyme inhibition in heart failure

In congestive heart failure, angiotensin-converting enzyme inhibitors (ACEIs) may prevent cardiac fibrosis via interaction with both angiotensin II and endothelin-1, which enhance myocardial collagen synthesis. However, whether endogenous bradykinin with an ACEI modifies the cardiac collagen architecture, affecting the endothelin system, has not yet been fully elucidated. We evaluated the changes in circulating hormonal factors, myocardial fibrosis and cardiac gene expression closely linked with heart failure, using an orally active specific bradykinin type 2 receptor antagonist, FR173657 (0.3 mg/kg/day, n = 6), with an ACEI, enalapril (1 mg/kg/day), in dogs with tachycardia-induced congestive heart failure (270 p.p.m., 22 days) and compared the effects with enalapril alone (n = 6). Although there were no differences observed in blood pressure, plasma renin activity, aldosterone and endothelin-1 levels, combined FR173657 significantly increased the cardiac expression of preproendothelin- 1 mRNA (P < 0.05) and collagen type I and type III mRNA (P < 0.05), and cardiac collagen deposits (P < 0.05), and decreased eNOS gene expression (P < 0.05) in the left ventricle compared with the ACEI-treated group. Furthermore, there was a significant negative correlation between the expression of preproendothelin- 1 and eNOS mRNA levels (r = -0.708, P < 0.001). In conclusion, bradykinin may prevent cardiac fibrosis in part via suppression of the local endothelin system in the failing heart through the enhancement of nitric oxide production under chronic angiotensin-converting enzyme inhibition.     

FR190997, a novel bradykinin B2 agonist, expresses longer action than bradykinin in paw edema formation and hypotensive response

Biological actions of a novel non-peptide B2 receptor agonist, FR190997, were examined by comparing them with those of bradykinin. The paw edema was induced by subcutaneous injection of 30 microl of solution of bradykinin (0.3, 0.6, and 1.2 nmol) or FR190997 (0.1, 0.3, and 0.9 nmol) into the right hind paw of ICR male mice. Bradykinin caused a dose-dependent edema formation, which peaked at 15 min and ceased after 150 min. FR190997 also formed a dose-dependent edema, peaking at 15-30 min with a slight delay compared to bradykinin and this response continued over 200 min. The edema formed by bradykinin or FR190997 was inhibited by pretreatment with HOE140 (1 mg/kg) injected intraperitoneally 30 min before the injection of each agonist. A novel non-peptide B2 antagonist, FR173657 (30 mg/kg, i.p. 30 min before the agonist), also diminished these responses by bradykinin and FR190997 dose-dependently. Indomethacin (10 mg/kg, i.p. 30 min before) inhibited the response to FR190997, suggesting that release of prostaglandins induced by the B2 agonistic action might be involved in this inflammatory process induced by FR190997. The hypotensive action of FR190997 was also examined. Intravenously injected FR190997 caused the systemic hypotensive response in Sprague-Dawley male rats anesthetized with pentobarbital. The potency of FR190997 was weaker than that of bradykinin, when compared with the maximal hypotension. Duration of the hypotensive response of FR190997 was significantly longer than that of bradykinin. These results indicate that FR190997 has the B2 agonistic action similar to bradykinin and is also a good tool for in vivo examination of the B2 receptor.