[A new fixed dose combination of fluticasone and formoterol in a pressurised metered-dose inhaler for the treatment of asthma]. / Une nouvelle association fixe de fluticasone/formotérol dans un aérosol-doseur pressurisé pour le traitement de l'asthme.

The combination of an inhaled corticosteroid and a long acting beta-2 agonist is indicated for the regular treatment of persistent moderate-to-severe asthmatics whose asthma is not controlled by inhaled corticosteroids and the occasional use of a short acting beta-2 agonist. The aim of this review is to give an overview of the rationale of combining formoterol and fluticasone and to analyze the clinical data concerning a new fixed combination of fluticasone and formoterol in a pressurised metered-dose inhaler with a dose counter (Flutiform(®)) that was approved for the treatment of asthma in France in 2013. The clinical studies provide evidence that combined fluticasone/formoterol is more efficacious than fluticasone or formoterol given alone, and provides similar improvements in lung function to fluticasone (Flixotide(®)) and formoterol (Foradil(®)) administered concurrently. The combination of fluticasone/formoterol gave a more rapid bronchodilatation than the combination fluticasone/salmeterol. As a whole, the combination of fluticasone/formoterol had similar efficacy and tolerability profiles to the combinations of either budesonide/formoterol or fluticasone/salmeterol.

Cannabinoids inhibit cholinergic contraction in human airways through prejunctional CB1 receptors.

BACKGROUND AND PURPOSE: Marijuana smoking is widespread in many countries, and the use of smoked synthetic cannabinoids is increasing. Smoking a marijuana joint leads to bronchodilation in both healthy subjects and asthmatics. The effects of Δ(9) -tetrahydrocannabinol and synthetic cannabinoids on human bronchus reactivity have not previously been investigated. Here, we sought to assess the effects of natural and synthetic cannabinoids on cholinergic bronchial contraction. EXPERIMENTAL APPROACH: Human bronchi isolated from 88 patients were suspended in an organ bath and contracted by electrical field stimulation (EFS) in the presence of the phytocannabinoid Δ(9) -tetrahydrocannabinol, the endogenous 2-arachidonoylglycerol, the synthetic dual CB1 and CB2 receptor agonists WIN55,212-2 and CP55,940, the synthetic, CB2 -receptor-selective agonist JWH-133 or the selective GPR55 agonist O-1602. The receptors involved in the response were characterized by using selective CB1 and CB2 receptor antagonists (SR141716 and SR144528 respectively). KEY RESULTS: Δ(9) -tetrahydrocannabinol, WIN55,212-2 and CP55,940 induced concentration-dependent inhibition of cholinergic contractions, with maximum inhibitions of 39, 76 and 77% respectively. JWH-133 only had an effect at high concentrations. 2-Arachidonoylglycerol and O-1602 were devoid of any effect. Only CB1 receptors were involved in the response because the effects of cannabinoids were antagonized by SR141716, but not by SR144528. The cannabinoids did not alter basal tone or contractions induced by exogenous Ach. CONCLUSIONS AND IMPLICATIONS: Activation of prejunctional CB1 receptors mediates the inhibition of EFS-evoked cholinergic contraction in human bronchus. This mechanism may explain the acute bronchodilation produced by marijuana smoking.

Tiotropium reduction of lung inflammation in a model of chronic gastro-oesophageal reflux.

Gastro-oesophageal reflux is frequent in chronic airway diseases and is considered a trigger for symptoms. In animal models, bilateral vagotomy or muscarinic antagonists prevent the increase in airway resistance and the microvascular leakage induced by acute oesophageal acid instillation. The present study investigates lung inflammation and remodelling in an animal model of chronic gastro-oesophageal reflux disease (GORD), and the effectiveness of pretreatments with tiotropium, atropine and dexamethasone. Mice were exposed to twice-daily intra-oesophageal HCl instillations for 21 days. Exposure to HCl causes: marked infiltration by inflammatory cells of the airways and of peribronchial areas; an increase in epithelial thickness; histological features of interstitial pneumonitis; an increase in cell numbers and in the levels of interleukin-8; and soluble intercellular adhesion molecule in bronchoalveolar lavage fluids, as well as of in vitro tracheal contractility. The administration of nebulised tiotropium or intraperitoneal atropine prior to each instillation of HCl, considerably inhibited all these changes. These results indicate a major role of acetylcholine in airway inflammation and remodelling in a GORD model, and demonstrate that tiotropium and atropine can prevent lung inflammation with an effectiveness similar to intraperitoneal dexamethasone, providing additional evidence that anticholinergics might contribute to the control of inflammatory processes in airway diseases.

Serotonin decreases HIV-1 replication in primary cultures of human macrophages through 5-HT(1A) receptors.

BACKGROUND AND PURPOSE: 5-HT (serotonin) is known to be involved in neuroinflammation and immunoregulation. The human immunodeficiency virus (HIV) targets cells such as monocytes/macrophages, which colocalize with 5-HT-releasing cell types, mostly platelets. In this study, we investigated the effects of 5-HT on HIV-1-infected macrophages in vitro. EXPERIMENTAL APPROACH: Human macrophages cultured in serum-free medium were treated over 7 days with 5-HT at three concentrations (0.01, 1 and 100 microM) with or without agonists and antagonists of 5-HT(1A) and 5-HT(2) receptors. After 7 days of treatment, macrophages were infected with HIV-1/Ba-L and virus replication was monitored over 16 days and expression of proviral HIV DNA was investigated by PCR after 24 h of infection. Cell surface expression of HIV-1/Ba-L receptor (CD4) and coreceptor (CCR5) was investigated by flow cytometry. The CCR5 ligand, macrophage inflammatory protein-1alpha (MIP-1alpha), was quantified by ELISA in cell culture supernatants and MIP-1alpha mRNA expression was assessed by reverse transcriptase-PCR. KEY RESULTS: In vitro, 5-HT downregulated the membranous expression of CCR5 and led to a decrease of HIV-1 infection, probably through its action on 5-HT(1A) receptors. 5-HT (100 microM) was also able to induce overexpression of MIP-1alpha mRNA leading to an increase of MIP-1alpha secretion by human macrophages. CONCLUSIONS AND IMPLICATIONS: The effects of 5-HT on HIV infection could be a consequence of the increase in MIP-1alpha concentrations and/or CCR5 receptor downregulation. These results suggest that 5-HT can inhibit the replication of HIV-1 in primary culture of human macrophages through its action on 5-HT(1A) receptors.

[Serotonin modulates HIV replication in primary culture of human macrophages: involvement of 5-HT(1A) sub-type receptors]. / Inhibition par la sérotonine de l'infection par VIH-1 des macrophages en culture primaire: rôle du sous-type 5-HT(1A) des récepteurs sérotoninergiques.

The neurotransmitter 5-hydroxytryptamine (5-HT), commonly known as serotonin, is released at peripheral sites from activated platelets. At inflammatory sites, macrophages and lymphocytes could be exposed to 5-HT concentrations up to 100 microM. Moreover, 5-HT could modulate cytokine secretion by monocytes/macrophages and immune functions through the uptake of 5-HT at these inflammatory sites from T cells and dendritic cells. HIV infection is also under the control of inflammatory processes (including T cell proliferation and cytokines secretion). On this basis, we studied explored herein the effects of 5-HT on HIV-1/Ba-L (macrophage-tropic virus) replication in primary cultures of human macrophages. This pharmacological study with isotype-selective receptor agonists and antagonist allowed us to show that the 100 microM 5-HT concentration via 5-HT(1A) subtype receptors could decrease HIV replication. This observation was associated with an increase of MIP-1alpha secretion such as an increase of MIP-1alpha mRNA production and with a decrease of HIV-coreceptor CCR5 cell surface expression. Our results point out for the first time the inhibitory effects of 5-HT on HIV replication in primary culture of human macrophages via activation of 5-HT(1A) subtype receptors.

[Sensory-nerves and airway inflammation: interaction with beta-2-adrenoceptor agonists]. / Le système neurosensoriel et l'inflammation bronchique: interaction avec les agonistes des récepteurs beta-2-adrénergiques.

beta-2-adrenoceptor agonists are used as bronchodilatators in asthma and chronic obstructive pulmonary disease (COPD) treatment. However, regular single use of these molecules may enhance bronchial hyperresponsiveness, a component of asthma and COPD. Indeed, pathophysiologic mechanisms underlying bronchial hyperresponsiveness remain unclear. Sensory nerves have been recently found in the respiratory tract and they play an important role in the regulation of bronchial responsiveness through the release of tachykinins and activation of vanilloid TRPV1 (Transient Receptor Potential Vanilloid 1) receptors. The purpose of this review is to highlight the most recent findings concerning the interactions between beta-2-adrenoceptor agonists and bronchial sensory nerves.

Effect of indacaterol, a novel long-acting beta2-agonist, on isolated human bronchi.

Indacaterol is a novel beta2-adrenoceptor agonist in development for the once-daily treatment of asthma and chronic obstructive pulmonary disease. The present study evaluated the relaxant effect of indacaterol on isolated human bronchi obtained from lungs of patients undergoing surgery for lung carcinoma. Potency (-logEC50), maximal relaxant effect (Emax) and onset of action were determined at resting tone. Duration of action was determined against cholinergic neural contraction induced by electrical field stimulation (EFS). At resting tone, -logEC50 and Emax values were 8.82+/-0.41 and 77+/-5% for indacaterol, 9.84+/-0.22 and 94+/-1% for formoterol, 8.36+/-0.16 and 74+/-4% for salmeterol, and 8.43+/-0.22 and 84+/-4% for salbutamol, respectively. In contrast to salmeterol, indacaterol did not antagonise the isoprenaline response. Indacaterol's onset of action (7.8+/-0.7 min) was not significantly different from that of formoterol (5.8+/-0.7 min) or salbutamol (11.0+/-4.0 min), but it was significantly faster than that of salmeterol (19.4+/-4.3 min). EFS-induced contractions were inhibited with -logIC50 values of 6.96+/-0.13 (indacaterol), 8.96+/-0.18 (formoterol), 7.18+/-0.34 (salmeterol) and 6.39+/-0.26 (salbutamol). Duration of action was >12 h for indacaterol and salmeterol, and 35.3+/-8.8 and 14.6+/-3.7 min for formoterol and salbutamol, respectively. In isolated human bronchi, indacaterol behaved as a long-acting beta2-adrenoceptor agonist with high intrinsic efficacy and fast onset of action.

Stimulation of the ADRB3 adrenergic receptor induces relaxation of human placental arteries: influence of preeclampsia.

Preeclampsia, which complicates 3-8% of pregnancies, is one of the leading causes of neonatal morbidity and mortality. Its pathophysiology remains unclear. The aim of the present study was to investigate the presence and the role of beta2- and beta2-adrenergic receptors (ADRB2 and ADRB3, respectively) in human placental arteries and to assess the influence of preeclampsia on ADRB responsiveness. SR 59119A, salbutamol, and isoproterenol (ADRB3, ADRB2, and nonselective ADRB agonists, respectively) induced a concentration-dependent relaxation of placental artery rings obtained from women with uncomplicated or preeclamptic pregnancies. SR 59119A-induced relaxation was unaffected by the blockade of ADRB1 and ADRB2 by 0.1 microM propranolol but was significantly decreased by the blockade of ADRB1, ADRB2, and ADRB3 by 10 microM propranolol. Both SR 59119A and salbutamol were associated with a significant increase in cAMP production that was significantly inhibited by pretreatment with 0.1 microM propranolol only for salbutamol. SR 59119A-induced relaxation (E(max) = 28% +/- 5% vs. 45% +/- 4%, respectively) and cAMP production (2.7 +/- 0.5 vs. 4.9 +/- 0.4 pmol/mg of protein, respectively; P < 0.01) were decreased in arteries obtained from preeclamptic compared to normotensive women. Both ADRB2 and ADRB3 transcripts were expressed at the same level between arteries from normotensive and preeclamptic women. Western blot analysis, however, revealed a decreased expression of the ADRB3 immunoreactive protein in arteries from preeclamptic compared to normotensive women. We suggest the presence of functional ADRB2 and ADRB3 in human placental arteries. Even if preeclampsia is associated with an impairment of the ADRB3 responsiveness, ADRB3 agonists may have future pharmaceutical implications in the management of pregnancy-related disorders.

Nerve growth factor is released by IL-1beta and induces hyperresponsiveness of the human isolated bronchus.

Nerve growth factor (NGF) is a neurotrophic factor essential for the development and survival of neurons, and is also an important mediator of inflammation. It is released by airway cells stimulated by interleukin (IL)-1beta. As IL-1beta induces airway hyperresponsiveness (AHR) to the tachykinin NK-1 receptor agonist [Sar9,Met(O2)11]-substance P in human isolated bronchi, the aim of this study was to determine whether IL-1beta was able to induce NGF release from isolated bronchi, and whether NGF might participate into IL-1beta-induced AHR. IL-1beta (10 ng x mL(-1); 21 degrees C; 15 h) increased the release of NGF from human isolated bronchi in vitro, and, in organ bath studies, the response of human bronchi to [Sar9,Met(O2)11]-substance P (0.1 microm). A significant correlation was found between these responses. AHR induced by IL-1beta was abolished by a blocking anti-human NGF antibody. Finally, NGF (1 ng x mL(-1); 37 degrees C; 0.5 h) by itself induced a significant increase in [Sar9,Met(O2)11]-substance P responsiveness. By contrast, it did not change the maximal contraction to acetylcholine. In conclusion, the present study clearly demonstrated that nerve growth factor may participate in the airway hyperresponsiveness induced by interleukin-1beta, which supports the neuro-immune cross-talk that may be active in the development of hyperresponsiveness in the human airways, and suggests nerve growth factor is active in the airways in asthma.

Paradoxal effect of salbutamol in an in vitro model of bronchoprotection.

Salbutamol-induced hyperresponsiveness to acetylcholine was investigated in human and guinea-pig isolated airways and cultured human airway smooth muscle cells. Salbutamol (10(-7)-10(-5) m) inhibited contractions induced by low concentrations of acetylcholine (10(-8)-10(-7) m) but potentiated contractions induced by higher concentrations of acetylcholine (10(-5)-10(-3) m). Pretreatment with the calcium channel antagonist nicardipine suppressed salbutamol-induced hyperresponse. Stimulation of cultured human airway smooth muscle cells with salbutamol (10(-6) m) amplified intracellular calcium concentration rise induced by acetylcholine (10(-5) m). Propranolol (10(-7) m), a beta1- and beta2-adrenoceptor antagonist, and ICI 118551 (10(-7)-10(-6) m), a beta2-adrenoceptor antagonist, suppressed the inhibitory effect of salbutamol but did not inhibit the hyperresponse on high concentrations of acetylcholine. In contrast, higher concentration of propranolol (10(-6) m) inhibited salbutamol-induced hyperreactivity. Effects of salbutamol were not affected by atenolol, a beta1-adrenoceptor blocker. Salbutamol-induced hyperresponsiveness is mediated through a mechanism involving calcium channel activation.

Beta3-adrenoceptor is the predominant beta-adrenoceptor subtype in human myometrium and its expression is up-regulated in pregnancy.

To assess whether pregnancy might influence the functionality and expression of human myometrial beta(2)- and beta(3)-adrenoceptors (beta(2)- and beta(3)-AR), we performed functional, binding, Western blot, and molecular biology experiments in human nonpregnant and near-term pregnant myometrium. Inhibition of spontaneous contractions induced by a beta(3)-AR agonist, SR 59119A, was significantly greater in pregnant, compared with nonpregnant, myometrial strips (E'(max) = 61 +/- 5% vs. 44 +/- 5% for pregnant and nonpregnant myometrium, respectively), whereas salbutamol, a beta(2)-AR agonist, was significantly less efficient in pregnant, compared with nonpregnant, myometrium (E(max) = 29 +/- 4 vs. 54 +/- 8%). Although two populations of binding sites corresponding to beta(2)- and beta(3)-AR were identified in both nonpregnant and pregnant myometrium, we found a clear predominance of the beta(3)-AR subtype. Moreover, beta(3)-AR binding sites were up-regulated 2-fold in myometrium at the end of pregnancy. Both beta(2)- and beta(3)-AR mRNA were expressed in human nonpregnant and pregnant myometrium. Contrary to beta(2)-AR, the expression of the beta(3)-AR transcripts and immunoreactive proteins was increased in pregnant, compared with nonpregnant, myometrium. Such compelling data suggest a predominant role for beta(3)-AR in the regulation of human myometrium contractility, especially at the end of pregnancy, which might have important consequences for the clinical management of preterm labor.

Interactions of tachykinin receptor antagonists with lipopolysaccharide-induced airway inflammation in mice.

1. Several observations suggest that tachykinins are involved in the pathogenesis of bronchopulmonary alterations. We have investigated the effect of antagonists for tachykinin NK1 (SR 140333), NK2 (SR 48968) or NK3 (SR 142801) receptors on inflammatory cell recruitment, tumour necrosis factor (TNF)-alpha and interleukin (IL)-6 release and matrix metalloproteinase (MMP)-9 activity in the bronchoalveolar lavage fluid (BALF) of mice exposed to lipopolysaccharide (LPS; 100 microg/mL aerosol for 30 min). 2. Treatment of mice with a combination of SR 140333 and SR 48968 (10(-6) mol/L, aerosol) significantly reduced the increase in the number of total cells and neutrophils and MMP-9 activity in the BALF of mice 2.5 h after LPS exposure. Treatment with the NK3 antagonist SR 142801 (10(-6) mol/L, aerosol) did not inhibit the influx of neutrophils, but markedly reduced the increase in TNF-alpha and IL-6 levels at 2.5 h and MMP-9 activity at 20 h. 3. These results show that the three tachykinin receptor antagonists may interfere with the development of airway inflammation, namely neutrophilia, TNF-alpha release or MMP-9 activity in the BALF of mice exposed to LPS and suggest that not only NK1 and NK2 receptors, but also NK3 receptors are involved in the modulation of the inflammatory response and airway remodelling.

[The therapeutic index in asthma: how should it be defined?]. / Comment définir un index thérapeutique dans le traitement de fond de l'asthme de l'adulte.

INTRODUCTION: The therapeutic index (efficacy/tolerance or benefit/risk ratio) is a major determinant of treatment decisions in asthma. METHODS: For the numerator, the therapeutic index depends on efficacy (maximal effect) and not potency (dose-response relationship). With regard to the denominator, several pharmacological factors influence the occurrence of side-effects, the acceptability of which also has to be considered. RESULTS: In asthma, some strategies have a more favourable therapeutic index than others;e.g additional treatment (long acting beta2 agonists, leukotriene receptor antagonists, theophylline) to inhaled corticosteroids instead of doubling the dose of the latter. Conversely, it is extremely difficult to compare the therapeutic indices of different molecules of inhaled corticosteroids. CONCLUSIONS: The potential risk of systemic side effects with long-term administration of high doses of inhaled corticosteroids suggests the need to seek the minimal effective dose.

The human near-term myometrial beta 3-adrenoceptor but not the beta 2-adrenoceptor is resistant to desensitisation after sustained agonist stimulation.

1. In order to compare the beta(2)- and beta(3)-adrenoceptor (beta-AR) desensitisation process in human near-term myometrium, we examined the influence of a pretreatment of myometrial strips with either a beta(2)- or a beta(3)-AR agonist (salbutamol or SR 59119A, respectively, both at 10 microm, for 5 and 15 h) on the relaxation and the cyclic adenosine monophosphate (cAMP) production induced by these agonists. 2. To assess some of the mechanisms potentially implicated in the beta-AR desensitisation process, we studied the influence of such treatment on the number of beta(2)- and beta(3)-AR binding sites, the beta(2)- and beta(3)-AR transcripts expression and the phosphodiesterase 4 (PDE4) activity. 3. Salbutamol, but not SR 59119A, concentration-response curve (CRC) was shifted by a 15 h salbutamol preincubation, with a significant difference in -log EC(20) values (6.31+/-0.13 vs 5.58+/-0.24, for control and 15 h salbutamol pretreatment, respectively, P<0.05). Neither salbutamol nor SR 59119A CRCs were modified after a 15 h preincubation with SR 59119A. 4. A 15 h exposure of myometrial strips to salbutamol significantly reduced the salbutamol-induced (0.60+/-0.26 vs 1.54+/-0.24 pmol mg(-1) protein, P<0.05), but not the SR 59119A-induced, cAMP production. No decrease in cAMP production was observed after a 15 h SR 59119A exposure. 5. A 15 h salbutamol exposure of myometrial strips significantly reduced the beta(2)- but not the beta(3)-AR binding site density, whereas no decrease in the number of beta(2)- and beta(3)-AR binding sites was observed after a 15 h SR 59119A treatment. 6. Neither PDE4 activity nor the beta(2)- and beta(3)-AR mRNA expression levels were affected by salbutamol or SR 59119A treatments. 7. Our results indicate that beta(3)-AR, but not beta(2)-AR, are resistant to the agonist-induced desensitisation. In our model, beta(2)-AR desensitisation is mediated by a decreased number of beta(2)-AR that was not explained by transcriptional regulation of the receptor.

Effects of cysteinyl leukotrienes in small human bronchus and antagonist activity of montelukast and its metabolites.

BACKGROUND: Evidence suggests that small airways contribute to clinically significant processes in asthma. Cysteinyl leukotrienes (CysLTs) are considered to be pivotal mediators in the pathogenesis of asthma. Montelukast (MK), a specific CysLT1 receptor antagonist, is metabolized in two main hydroxylated metabolites (termed M5 and M6, respectively). OBJECTIVES: The aims of this study were to compare the responsiveness of small and large human bronchi to the three CysLTs, to evaluate the antagonist activity of MK, M5 and M6 in these preparations of human bronchi, and to characterize the CysLT receptors involved in the contractile response. METHODS AND RESULTS: In isolated small bronchus (i.d. 0.5-2 mm), the potencies (-log molar EC50) of LTC4, LTD4 and LTE4 were 9.3 (n=11), 9.1 (n=30) and 8.4 (n=14), respectively. The three CysLTs were about 30-fold more potent in small bronchi than in larger bronchi (i.d. 4-6 mm). In small bronchi, MK significantly shifted to the right the CysLT concentration-effect curves with pA2 values against LTC4, LTD4 and LTE4 of 9.1 (n=3), 9.0 (n=11) and 8.7 (n=5), respectively. The antagonist potencies of M6 and M5 were similar to MK and fivefold lower, respectively. A similar activity of MK against the three CysLTs suggested that CysLT1 receptors are involved in the contraction of human bronchus. Analysis by RT-PCR also indicated that human bronchus mainly expressed CysLT1 receptors. CONCLUSION: MK exerts a potent antagonist activity against the particularly potent constricting effects of CysLTs in isolated human small bronchi, which only expressed the CysLT1 receptor subtype. The metabolites of MK are also potent in vitro antagonists, but may not participate in the therapeutic activity of MK due to their low plasma concentrations in patients treated with the recommended dose of MK.

Role of tachykinins in the bronchoconstriction induced by HCl intraesophageal instillation in the rabbit.

Gastroesophageal acid reflux (GER) is a common disorder associated with the exacerbation of asthma. In this study we investigated the effects on the airways of intraoesophageal HCl instillation in the rabbit and the role of tachykinins in these effects. In anaesthetized New Zealand rabbits bronchopulmonary functions [total lung resistance (R(L)) and dynamic compliance (C(dyn))] were calculated before and after HCl intraoesophageal instillation. Infusion of HCl induced a significant bronchoconstriction (P < 0.05) in the terms of R(L) and C(dyn) changes, that were increased by phosphoramidon pre-treatment and reduced by capsaicin pre-treatment. Moreover, a pre-treatment with SR 48968, a tachykinin NK2 receptor antagonist, or SR 140333, a NK1 receptor antagonist, significantly inhibited the bronchoconstriction induced by intraoesophageal HCl infusion in terms of R(L) and C(dyn)changes. Finally, the HCl induced bronchoconstriction was unaffected by SR 142801, a tachykinin NK3 receptor antagonist. In conclusion these results suggest that bronchoconstriction induced by intraoesophageal HCl infusion is mainly dependent on the release of tachykinins and that both NK1 and NK2 tachykinin receptors are involved.

SR 142801, a tachykinin NK(3) receptor antagonist, prevents beta(2)-adrenoceptor agonist-induced hyperresponsiveness to neurokinin A in guinea-pig isolated trachea.

We investigated whether fenoterol was able to enhance contractile responsiveness to neurokinin A (NKA) on the guinea-pig isolated trachea. We then studied the effects of two inhibitors of nuclear factor kappa B (NFkappaB), gliotoxin and pyrrolidine dithiocarbamate, and of the tachykinin NK(1), NK(2) and NK(3) receptor antagonists, SR 140333, SR 48968 and SR 142801 and determined whether tachykinin receptor gene expression was up-regulated in the trachea after exposure to fenoterol. Fenoterol (0.1 microM, 15 h, 21 degrees C) induced an increased contractile response to NKA (mean of difference in maximal tension between control and fenoterol +/- S.E.M; +0.47 +/- 0.14 g, n = 26, P < 0.01). This hyperresponsiveness was strongly reduced by co-incubation with gliotoxin (0.1 microg/ml) or pyrrolidine dithiocarbamate (0.1 mM) and abolished by SR 140333 (0.1 microM) and SR 142801 (0.1 microM). SR 48968 (0.1 microM) diminished the tracheal contractility to NKA but failed to reduce the hyperreactivity induced by fenoterol. Tachykinin NK(1) receptor (NK(1)R), NK(2) receptor (NK(2)R) and NK(3) receptor (NK(3)R) gene expression was analyzed by semiquantitative RT-PCR. Compared to control tissues, NK(1)R and NK(2)R mRNA expression was increased by about 1.6-fold and 1.4-fold, respectively, in tissues treated with fenoterol. We were unable to detect the presence of NK(3)R mRNA in the guinea-pig trachea. In conclusion, fenoterol induces tracheal hyperresponsiveness to NKA and an up-regulation of NK(1)R and NK(2)R gene expression. The hyperresponsiveness implicates the NFkappaB pathway and is abolished by tachykinin NK(1) (SR 140333) and NK(3) (SR 142801) receptor antagonists.

Tachykinins and airway microvascular leakage induced by HCl intra-oesophageal instillation.

Gastro-oesophageal reflux is a common clinical disorder associated with a variety of respiratory symptoms, including chronic cough and exacerbation of asthma. In this study, the potential role of acid-induced tachykinin release was examined in guinea pigs and rabbits, by examining the effects of the tachykinin NK1 and NK3 receptors antagonists (SR 140333 and SR 142801, respectively) (1-10 mg x kg(-1)) on plasma protein extravasation induced in airways by hydrochloric acid (HCl) infusion in the oesophagus. Guinea pigs were anaesthetised with urethane, while rabbits were subject to neuroleptoanalgesia with hypnorm. Airway vascular leakage was evaluated by measuring extravasation of Evans blue dye. All animals were pretreated with atropine (1 mg x kg(-1) i.p.), propranolol (1 mg x kg(-1) i.p.), phosphoramidon (2.5 mg x kg(-1) i.v.) and saline or tachykinin receptor antagonists (1-10 mg x kg(-1) i.p.). Infusion of 1 N HCl into the oesophagus led to a three- and five-fold increase in plasma extravasation in the main bronchi and trachea, respectively. This increase was largely prevented by the tachykinin NK1 and NK3 receptor antagonists SR 140333 and SR 142801 (1-10 mg x kg(-1)). These results suggest that protein extravasation in the airways, as induced by intraoesophageal HCl infusion, is mainly dependent on the release of tachykinins, and that both NK1 and NK3 tachykinin receptors are involved. The results suggest that HCl-induced sensory nerve stimulation may act in the periphery on intermediate neurons and/or ganglia where NK3 receptors have been shown to play an important role.

Relaxation of proximal and distal isolated human bronchi by halothane, isoflurane and desflurane.

Volatile anaesthetics relax airway smooth muscle in vitro. The amount of relaxation might depend on the type and concentration of volatile anaesthetics, the calibre and precontraction level of the bronchi, and also on the species considered. These effects were investigated on isolated human bronchi. Isometric relaxations produced by halothane, isoflurane and desflurane bubbled on human bronchial rings precontracted with carbachol were recorded and compared with time controls. Volatile anaesthetics induced a concentration-dependent relaxation at 0.66, 1.33 and 2 minimum alveolar concentration (MAC). The relaxation was greater in mildly (carbachol 3x10(-7) M) than in highly (carbachol 2x10(-6) M) precontracted bronchi. Halothane was more potent in relaxing distal as compared to proximal bronchi; this differential effect was less pronounced with isoflurane and not observed with desflurane. While the three volatile anaesthetics induced similar relaxation on proximal bronchi, halothane was significantly more potent than desflurane on distal bronchi, with isoflurane being intermediate. The relaxation induced by 1.33 MAC of halothane, isoflurane and desflurane on moderately precontracted distal bronchi (carbachol 1x10(-6) M) was attenuated by pretreatment with glibenclamide 1x10(-5) M. In conclusion, halothane, isoflurane and desflurane exert direct but differential relaxant effects on human isolated bronchial smooth muscle. This may provide supplemental bronchodilation during anaesthesia. Although adenosine triphosphate-sensitive K+ channels are involved in these relaxant effects, they are unlikely to explain the observed differences between the three volatile anaesthetics.

[The role of endothelin in the physiology and pathophysiology of airways]. / Rôle de l'endothéline dans la physiologie et la physiopathologie des voies aériennes respiratoires.

Following its discovery in 1988 endothelin initially attracted attention in the cardiovascular field. It is only more recently that the involvement of this peptide, and its role in the physiology and pathophysiology of the airways, has been established. Endothelin receptors have been demonstrated in the majority of cells in the airways from the main bronchi to the alveoli, where endothelin exerts endocrine and paracrine effects on the fine regulation of bronchial muscular tone, the process of cell proliferation and repair, alveolar and bronchial secretion as well as microvascular permeability. The intra and extracellular pathways of the mechanisms of action of endothelin are currently under investigation. Furthermore, it has been shown in the last ten years that endothelin is also, in certain circumstances, a powerful inflammatory mediator. The implication of endothelin in pathological processes such as asthma, chronic airflow obstruction, bronchiectasis, some broncho-pulmonary cancers, ideopathic pulmonary fibrosis, and ARDS is currently suspected if not proven. This opens up the possibility of new therapies. The object of this revue is to summarise the current knowledge of the role played by endothelin in the physiology and pathophysiology of the airways and respiratory system.