The characteristics of inhibition of histamine release from human lung fragments by sodium cromoglycate, salbutamol and chlorpromazine

In vitro effects of antipsychotics on mitochondrial respiration

Assessment of drug-induced mitochondrial dysfunctions is important in drug development as well as in the understanding of molecular mechanism of therapeutic or adverse effects of drugs. The aim of this study was to investigate the effects of three typical antipsychotics (APs) and seven atypical APs on mitochondrial bioenergetics. The effects of selected APs on citrate synthase, electron transport chain complexes (ETC), and mitochondrial complex I- or complex II-linked respiratory rate were measured using mitochondria isolated from pig brain. Complex I activity was decreased by chlorpromazine, haloperidol, zotepine, aripiprazole, quetiapine, risperidone, and clozapine. Complex II + III was significantly inhibited by zotepine, aripiprazole, quetiapine, and risperidone. Complex IV was inhibited by zotepine, chlorpromazine, and levomepromazine. Mitochondrial respiratory rate was significantly inhibited by all tested APs, except for olanzapine. Typical APs did not exhibit greater efficacy in altering mitochondrial function compared to atypical APs except for complex I inhibition by chlorpromazine and haloperidol. A comparison of the effects of APs on individual respiratory complexes and on the overall mitochondrial respiration has shown that mitochondrial functions may not fully reflect the disruption of complexes of ETC, which indicates AP-induced modulation of other mitochondrial proteins. Due to the complicated processes associated with mitochondrial activity, it is necessary to measure not only the effect of the drug on individual mitochondrial enzymes but also the respiration rate of the mitochondria or a similar complex process. The experimental approach used in the study can be applied to mitochondrial toxicity testing of newly developed drugs.

Methods for Testing Immunological Factors

Hypersensitivity reactions can be elicited by various factors: either immunologically induced, i.e., allergic reactions to natural or synthetic compounds mediated by IgE, or non-immunologically induced, i.e., activation of mediator release from cells through direct contact, without the induction of, or the mediation through immune responses. Mediators responsible for hypersensitivity reactions are released from mast cells. An important preformed mediator of allergic reactions found in these cells is histamine. Specific allergens or the calcium ionophore 48/80 induce release of histamine from mast cells. The histamine concentration can be determined with the o-phthalaldehyde reaction.

Cromoglycate and nedocromil: influence on airway reactivity

Although basic mechanisms of bronchial hyper-responsiveness (BHR) are still incompletely understood, inflammation of airways is likely to play a fundamental role in modulating BHR in patients with asthma. The involvement of several inflammatory cells (eosinophils, mast cells, lymphocytes, neutrophils, macrophages and platelets) and of bioactive mediators secreted by these cells in the pathogenesis of asthma is well documented. Sodium cromoglycate and nedocromil sodium are two pharmacological agents which have anti-allergic and anti-inflammatory properties. Their clinical effectiveness in mild to moderate asthma, and the capacity to reduce BHR under different natural and experimental conditions, make them valuable drugs for maintenance therapy in patients with asthma.

Aminophilline suppress the release of chemical mediators in treatment of acute asthma

BACKGROUND

The control of airway inflammation is crucial for management of asthma. Theophylline has been demonstrated to have an anti-inflammatory effect as a long-term-medication for asthma in various studies. In the present study we attempted to clarify if aminophylline, a theophylline derivative, could act as an anti-inflammatory agent as well as a bronchodilator in the treatment for acute asthma exacerbations.

METHODS

Patients are initially treated either with an intravenous infusion of aminophylline or with inhalation of salbutamol. Pro-inflammatory mediators such as eosinophil cationic protein (ECP), histamine, serotonin, thromboxane B2, leukotriene C4 were measured before and one hour after the initial treatment. Clinical parameters such as peak expiratory flow (PEF) and SpO2 were also checked during the studies.

RESULTS

Significant improvements of PEF and SpO2 with both aminophylline and salbutamol treatment were seen. Furthermore, significant decreases of ECP, histamine, and serotonin were observed with aminophylline but not with salbutamol.

CONCLUSIONS

Suppressing the release of pro-inflammatory mediators may play a role, at least in part, in the beneficial effects of aminophylline in the treatment of acute exacerbations in asthma. Additionally, this study indicated that treatment with aminophylline is at least as beneficial as nebulized salbutamol in the restoration of lung function.

Differential effects of beta2-adrenoceptor desensitization on the IgE-dependent release of chemical mediators from cultured human mast cells

In the present study, we examined the inhibitory effects of the beta2-adrenoceptor agonists isoproterenol, salbutamol, fenoterol, and clenbuterol, on the release of chemical mediators from cultured human mast cells after prolonged treatment with the agonists. Although preincubation of sensitized mast cells for 10 min with beta2-adrenoceptor agonists potently inhibited mediator release, prolongation of the preincubation period up to 240 min attenuated the inhibition. The attenuation of histamine release inhibition was potent when compared with that of prostaglandin D2 (PGD2) and cysteinyl leukotriene (LT) release inhibition. In contrast, forskolin inhibited mediator release and the inhibition increased gradually in proportion to the preincubation period. The reduced inhibition by the beta2-adrenoceptor agonists was compensated for by simultaneous treatment with cholera toxin. The beta2-adrenoceptor agonists elevated intracellular cAMP levels after 10-min incubation and the elevated levels were almost comparable to those after 240-min incubation. Forskolin elevated the intracellular cAMP levels more potently after incubation for 240 min than after 10 min. When mast cells were incubated for 3 d with the beta2-adrenoceptor agonists, similar attenuation of mediator release inhibition was observed. Elevation of intracellular cAMP levels was also attenuated, although beta2-adrenoceptor mRNA expression was potentiated. The present results collectively indicate that the attenuation of mediator release inhibition by beta2-adrenoceptor agonists under the present experimental conditions involves uncoupling between beta2-adrenoceptors and Gs proteins. Furthermore, the beta2-adrenoceptor desensitization causes differential attenuating effects on the inhibition of histamine, PGD2, and LT release, suggesting that downstream events involved in each inhibitory pathway have different sensitivity to receptor desensitization.

FK506 inhibition of histamine release and cytokine production by mast cells and basophils

Histamine release and cytokine production by mast cells and basophils are thought to be closely involved in the pathogenesis of allergic diseases. Some reports show that FK506 (tacrolimus hydrate) inhibited histamine release and cytokine production by mast cells and basophils. However, as the effects of FK506 has not been compared with those of clinically used drugs in those reports, the clinical relevancy of FK506 inhibition remained unclear. In this paper, we compared the actions of FK506 with those of steroids or disodium cromoglycate (DSCG) which has been clinically used. FK506 inhibited histamine release by Brown-Norway rat peritoneal mast cells more potently than steroids and especially DSCG. FK506 also inhibited histamine release by a mast rat basophilic leukemia (RBL)-1 cell line and human peripheral blood basophils, whereas steroids failed to inhibit histamine release by human basophils. FK506 as well as steroids inhibited TNF-alpha and IL-4 production by RBL-1 cells. FK506 was therefore more effective than steroids and DSCG in inhibiting histamine release, and it also had the ability of inhibiting cytokine production by mast cells as steroids do. We concluded that FK506 might regulate allergic diseases via these actions, judging from the viewpoint of clinical relevancy.

Inflammation in asthma: the cornerstone of the disease and target of therapy

Asthma is a chronic disease associated with variable levels of airflow obstruction. Considerable evidence has been obtained to show that airway inflammation is a major factor in the pathogenesis of asthma in associated bronchial hyperresponsiveness, and in the level of disease severity. The inflammatory pattern in asthma is multicellular in nature, with mast cells, neutrophils, eosinophils, T lymphocytes, and epithelial cells participating in the response. Furthermore, it is known that mediators, cytokines, and chemokines from these cells contribute to the orchestration of the inflammatory process. Because airway inflammation appears to be a critical etiologic feature of asthma, it has become the target of therapy. In this review the features of airway inflammation will be examined, and the effect of therapeutic agents on markers of airway injury will be discussed. Establishing, understanding, and finally controlling the features of airway inflammation have given insight to disease pathogenesis and the effectiveness of various treatments. The integral role of inhaled corticosteroids in modifying the complex inflammatory component of asthma will be explored, with special focus on the high degree of efficacy associated with this treatment--vis-á-vis other therapeutic agents--in preventing or blocking specific proinflammatory markers.

The effects of anti-asthma drugs on mediator release from cultured human mast cells

BACKGROUND

A method for generating human mast cells in vitro was recently established. Little is known about the pharmacological profiles of allergic mediator release from cultured mast cells.

OBJECTIVE

The main objective was to investigate the nature of cultured mast cells from a pharmacological point of view. We examined the effect of anti-asthma drugs on the release of histamine, sulfidoleukotrienes (LTs) and prostaglandin D2 (PGD2) from the cultured mast cells.

METHODS

Using the method established by Saito et al. we cultured cord blood mononuclear cells in the presence of 80 ng/mL stem cell factor (SCF), 50 ng/mL interleukin-6 (IL-6) and 300 nmol/L prostaglandin E2 (PGE2), and obtained almost pure (> 99%) mast cells. We sensitized cultured mast cells with immunoglobulin E (IgE)-rich serum, and then treated them with some anti-asthma drugs before challenge with anti-human IgE. Released histamine, LTs and PGD2 were measured by high-performance liquid chromatography, commercial enzyme-linked immunosorbent assay (ELISA) and enzyme immunoassay (EIA) systems, respectively.

RESULTS

The cultured mast cells released histamine, LTs and PGD2 following immunological stimulation through IgE. The mast cell stabilizing agents disodium cromoglycate (DSCG, 1 mmol/L) and azelastine (100 micromol/L) significantly inhibited the release of these three mediators. The beta-adrenoceptor agonists isoproterenol, salbutamol, and clenbuterol also inhibited all three mediators' release in a concentration-dependent manner. The non-selective and selective phosphodiesterase (PDE) inhibitors theophylline, rolipram, and cilostazol had no significant effect on mediator release at clinically useful concentrations. BAY x 1005 (a 5-lipoxygenase-activating protein inhibitor) inhibited the LTs release, whereas indomethacin (a cyclo-oxygenase I and II inhibitor) and NS-398 (a cyclo-oxygenase II inhibitor) inhibited PGD2 release.

CONCLUSIONS

The present results indicate that cultured mast cells release histamine, LTs and PGD2 following IgE crosslinking. Anti-asthma drugs showed a characteristic suppression of the release of each mediator. The suppressive actions of these drugs are similar to their pharmacological actions on human lung mast cells. These results suggest that cultured mast cells are useful for the analysis of function and pharmacological profiles of lung mast cells.

Contractile responses of proximal and distal trachea segments isolated from rats subjected to immunological stimulation: role of connective tissue mast cells

1. Anaphylaxis-induced contractions of proximal and distal tracheal segments isolated from 14-day ovalbumin (OA)-sensitized rats were studied. 2. OA-induced contractions in distal segments were significantly greater than those observed in proximal segments. 3. Pretreatment of the rats with compound 48/80 or with sodium cromoglycate (SCG) aerosolization significantly reduced OA-induced contractions of trachea distal segments, whereas the contractions of proximal segments were reduced only by compound 48/80. 4. Mepacrine reduced and indomethacin increased the OA-induced contractions in all tracheal segments. Nor-dihydroguaiaretic acid increased the OA-induced contractions in distal tracheal segments, whereas dazoxiben inhibited the contractions in these same segments; neither of these drugs had any effect on the contractions in proximal tracheal segments. 5. The depletion of connective tissue mast cells and subsequent in vitro treatment with indomethacin increased the OA-induced contractions in both segments. 6. We conclude that the contractions of tracheal muscle from OA-sensitized rats depends on the topographic and anatomical origin of the airway tissue. 7. Mediators released by connective tissue mast cells in proximal and distal segments play a pivotal role in this response and may account for variations in the intensity of contraction seen after the addition of OA.

Stimulation of dispersed nasal polyp cells by hyperosmolar solutions

It has been suggested that hyperosmolarity may be one of the stimuli that provoke exercise-induced asthma and rhinitis. We investigated whether changes in osmolarity could result in increased levels of mediator release from nasal cells. Cells were dispersed from nasal polyps by enzymatic digestion and were incubated for 15 minutes with solutions of varying osmolarity obtained by the addition of mannitol to Hanks' balanced salt solution. After incubation was performed, cell supernatants were removed, and the release of 15-hydroxyeicosatetraenoic acid, prostaglandin2 leukotriene B4, and fibronectin was measured. Lactate dehydrogenase was measured to assess cell viability. Epithelial cells made up 40% to 60% of cells and mononuclear cells 40% to 65%. At 900 mOsm/kg H2O, which has been suggested as the osmolarity of the fluid lining the airways during exercise, we observed a significant increase (Wilcoxon W test) in the release of 15-hydroxyeicosatetraenoic acid (p < 0.008), leukotriene B4 (p < 0.008), and prostaglandin2 (p < 0.008), but no significant increase in the release of fibronectin was seen. No significant increase was seen between lactate dehydrogenase and 15-hydroxyeicosatetraenoic acid release, suggesting that the increase in mediator levels was not caused by cell death. These results show that hyperosmolar solutions can induce activation of nasal cells, which may at least partly explain rhinitis caused by exercise.

An explanation of the asthma paradox

The morbidity and mortality associated with asthma are rising, despite increased usage of anti-asthma medications. This report attempts to provide a plausible hypothesis for the "asthma paradox." The hypothesis involves the role of mast cell degranulation as an endogenous anti-inflammatory mechanism to prevent antigens from entering the lower airways and to limit the extent of the subsequent repair process. By treating symptoms of asthma with drugs such as beta 2 agonists that inhibit mast cell degranulation, increased inflammation is allowed to occur, which may lead to the chronic appearance of excess repair tissue and the acceleration of the disease process.

Effect of salbutamol, fenoterol, and sodium cromoglycate on the release of heparin from sensitized human lung fragments challenged with Dermatophagoides pteronyssinus allergen

Heparin from degranulating mast cells influences a wide range of cellular and humoral reactions associated with allergic inflammation and asthma. Agents that inhibit mast cell degranulation may therefore compromise the moderating effects of heparin in the tissues and result in worsening inflammation and other associated pathology. This study measures heparin release from allergen-challenged human lung tissue and compares the effect of the mast cell stabilizing beta 2-agonists, salbutamol and fenoterol, and a non-beta 2-agonist, sodium cromoglycate, on the release of heparin. Pieces of lung tissue 2 to 3 mm3 were sensitized with high titer Dermatoaphagoides pteronyssinus-specific IgE serum and challenged with D. pteronyssinus allergen, with and without prior addition of salbutamol, fenoterol, or sodium cromoglycate. Dextran sulfate was added to the mixture to prevent the binding of heparin to tissue proteins. Heparin was released together with histamine after challenge. The mean and 95% confidence interval of prechallenge and postchallenge heparin concentrations in the lung tissue filtrates were 0.10 IU/ml (0.07, 0.12) and 0.24 IU/ml (0.17, 0.30), respectively (P < 0.001). Addition of the beta 2-agonists produced a mean inhibition of released heparin of 71% (50, 92), and 73% (55, 91), respectively. Sodium cromoglycate gave a 35% (20, 51) inhibition that was significantly less than that produced by the beta 2-agonists (P < 0.01). The beta 2-agonists salbutamol and fenoterol strongly inhibited heparin release from mast cells. The therapeutic use of mast cell stabilizing agents may therefore be potentially detrimental to the control of allergic inflammation and other associated pathologies.

Neutrophil-induced human bronchial hyperresponsiveness in vitro--pharmacological modulation

Although it has been postulated that inflammatory cells cause the bronchial hyperresponsiveness which is diagnostic of asthma, until recently there has been little direct evidence of such a link. We have recently shown that calcium ionophore-activated human neutrophils and eosinophils can induce a state of human airway hyperresponsiveness in vitro. In this study we have shown that the anti-inflammatory agent nedocromil sodium, 10(-7) M, inhibited the hyperresponsiveness induced by products released from ionophore activated neutrophils but did not inhibit the release of leukotriene B4 from the same cells. Neutrophil-induced bronchial hyperresponsiveness was also inhibited by pre-treatment of the bronchial tissues with a thromboxane A2 and prostaglandin receptor antagonist, GR32191, 10(-7) M. These findings indicate that cyclooxygenase products are involved in bronchial hyperresponsiveness induced by inflammatory cell products in vitro and that their release can be inhibited by nedocromil sodium.

Duration of preventive effect of inhaled salbutamol on early airway response to allergen in asthmatic subjects

Salbutamol is known to effectively prevent early asthmatic response (EAR) after specific bronchial provocation test (sBPT) in asthmatic subjects, but the time-course of this protection is not known. In this study the effects of 200 micrograms salbutamol inhaled 2 h before sBPT were compared with 200 micrograms salbutamol inhaled 10 min before sBPT in eight asthmatic subjects sensitized to Phleum pratensis (PP) or Dermatophagoides pteronyssinus (DP). All subjects showed an EAR (% decrease in FEV1 from baseline value: 30.4 +/- 11%) in a preliminary sBPT performed with cumulated doses of extracts of PP or DP titrated in biological units (BU). Each subject performed, on two different days, in a random, double-blind, cross-over study, two puffs of placebo 2 h before sBPT and two puffs of salbutamol 10 min before sBPT (treatment A) or two puffs of salbutamol 2 h before sBPT and two puffs of placebo 10 min before sBPT (treatment B). Baseline FEV1 were similar in both tests. In treatment B, 10 min, 1 h and 2 h after salbutamol inhalation, FEV1 increased significantly with respect to placebo inhalation in treatment A. Ten minutes after salbutamol inhalation in treatment A, FEV1 became similar to that obtained 2 h after salbutamol inhalation and 10 min after placebo in treatment B. Allergen inhalation induced an EAR in only one out of eight subjects after treatment A, and five of the eight subjects after treatment B.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of an animal model of late asthmatic response in guinea pigs and effects of anti-asthmatic drugs

We developed an animal model of late asthmatic response (LAR) in guinea pigs and examined the effects of anti-asthmatic drugs and peptide leukotriene antagonist, MCI-826, on this model. Bronchial challenge of DNP-As (Dinitrophenylated-Ascaris suum extract)-sensitized guinea pigs induced a biphasic increase in pulmonary resistance (RL) with the maximal increase being observed immediately (IAR, immediate asthmatic response) and 3 to 5 hr after antigen inhalation (LAR). Twelve of 22 guinea pigs showed both IAR and LAR. The average increases in RL for all 22 guinea pigs at IAR and LAR, were 168 +/- 13 and 207 +/- 16 (% of baseline value), respectively. Bronchoalveolar lavage (BAL) fluid of guinea pigs that received antigen, revealed increases in the numbers of eosinophils (7.3-fold compared to animals receiving saline) and neutrophils (5.3-fold compared to animals receiving saline) 4 hr after antigen inhalation. When DSCG (disodium cromoglycate) was administered (10 mg/kg, i.v.) before antigen challenge, DSCG significantly inhibited IAR (p less than 0.05) and slightly inhibited LAR (p less than 0.2). Theophylline (30 mg/kg, p.o.) administered before antigen, slightly inhibited both IAR and LAR (p less than 0.2). Salbutamol (3 mg/kg, i.p.) administered before antigen, significantly inhibited IAR (p less than 0.05), but did not affect LAR. These results were correlated with clinical trials. Moreover, peptide leukotriene antagonist, MCI-826, (E)-2,2-Diethyl-3'-[2-[2-(4- isopropyl)thiazolyl] ethenyl]succinanilic acid (0.1 mg/kg, p.o.) administered 1 hr before antigen challenge, significantly inhibited both IAR and LAR (p less than 0.05). MCI-826 (0.1 mg/kg, p.o.) administered 1.5 hr after antigen inhalation, also inhibited LAR (p less than 0.05). Analysis of BAL fluid revealed that DSCG and MCI-826 significantly inhibited the increase in eosinophils (p less than 0.05). These data suggest that leukotriene plays an important role in the development of the pathogenesis of LAR, and that our model is an useful experimental model for investigating the mechanisms of LAR and examining the effects of several anti-asthmatic drugs on LAR.

Inhibition profiles of sodium cromoglycate and nedocromil sodium on mediator release from mast cells of human skin, lung, tonsil, adenoid and intestine

We have studied an aspect of the functional heterogeneity of human mast cells, namely responsiveness to the inhibitory effects of sodium cromoglycate and nedocromil sodium. The effects of these drugs were examined on the release of histamine and PGD2 from mast cells of human skin, lung, tonsils, adenoids and intestine. A high concentration, 1000 microM, of sodium cromoglycate was required to significantly inhibit histamine release from lung and tonsillar mast cells. Nedocromil sodium, 1000 microM, was more effective than sodium cromoglycate against histamine release from lung, tonsillar and adenoidal cells. Both compounds showed tachyphylaxis in lung and tonsillar mast cells but not in adenoidal and intestinal mast cells. In contrast, in intestinal mast cells, the effect of nedocromil sodium was weaker and more variable than sodium cromoglycate. Skin mast cells differed from mast cells of the other anatomical sites in being unresponsive to sodium cromoglycate and nedocromil sodium. Our results confirm that high concentrations of sodium cromoglycate and nedocromil sodium are required to achieve even modest inhibition of mediator release from human mast cells under in vitro conditions. Notwithstanding this, the results also indicate that differences exist among skin, lung, tonsillar, adenoidal and intestinal mast cells with respect to their sensitivity to sodium cromoglycate and nedocromil sodium, thus extending our knowledge of functional heterogeneity within the human mast cell populations.

In vivo release of 15-HETE and other arachidonic acid metabolites in nasal secretions during early allergic reactions

The purpose of this study is to examine the "in vivo" release of 15-HETE and other arachidonic acid metabolites in nasal secretions following a challenge with "Dermatophagoides Pteronyssinus" in patients with allergic rhinitis and non-allergic controls. In addition, we examine the effects of a membrane stabilizer, such as sodium cromoglycate, on these metabolites. Thirteen allergic subjects and seven healthy controls are studied. 15-HETE, peptide leukotrienes, LTB4, PGD2, PGE2 and PGF2 alpha levels are evaluated before and after nasal challenge in sodium cromoglycate treated and untreated subjects. This study provides "in vivo" evidence that the pathophysiological responses to nasal antigen challenge could be related to the release of 15-HETE as well as other arachidonic acid metabolites, mainly arising from the lipoxygenase pathway.

Salbutamol plus beclomethasone dipropionate, but not salbutamol alone, completely prevent early and late asthmatic responses to allergen

The effect of a week treatment with inhaled salbutamol plus placebo (S+P) vs. salbutamol combined with beclomethasone dipropionate (S+BDP) on early and late asthmatic responses to inhaled allergen was studied in ten atopic patients in a randomized, double-blind, cross-over study. All patients had previously shown a dual type response to the specific bronchial provocative test (sBPT). Each patient performed two periods of treatment for a week, with a 15 day interval between them: (a) salbutamol 0.3 mg, tid + placebo; (b) salbutamol 0.3 mg+BDP 0.2 mg, tid; at the end of each treatment period, sBPT was performed and the last treatments were given 1.5-2 h before and 3-4 h after allergen challenge. S + BDP completely prevented both early and late responses to allergen, while S + P reduced but did not completely inhibit early and late responses. The difference between the two treatments was significant for early and late asthmatic responses. Non-specific bronchial hyperresponsiveness to methacholine was performed before each treatment period, after 6 days of treatment before sBPT and the day after sBPT at the end of the treatment period; there was only a mild increase in PD15FEV1 methacholine after 6 days of treatment with S + BDP in comparison with S + P treatment. These results suggest that salbutamol plus beclomethasone may be used effectively in the prophylaxis of early and late asthmatic reactions induced by allergen in sensitized subjects.

Biological properties of human skin mast cells

Mast cells and basophils, although sharing many constitutive properties, are quite distinct in their development, functions and biological properties. Mast cell granules are composed of a macromolecular matrix of proteoglycan and neutral protease of which heparin and tryptase, respectively, are predominant. The distribution of the other major neutral protease, chymase, allows human mast cell subpopulations to be subdivided immunocytochemically. All human mast cells respond to IgE-dependent stimulation with the secretion of the preformed mediator, histamine, and the newly generated lipid-derived eicosanoids PGD2 and LTC4. Although amounts of these products vary between mast cells dispersed from different tissues, it is uncertain whether this reflects true heterogeneity. Mast cells of the human skin, but not those of other tissues, are sensitive to stimulation by substance P, compound 48/80 and other basic non-immunological stimuli. The mechanism of mediator secretion induced by these agents is distinct from that induced by IgE-dependent stimulation. However, the morphological characteristics of degranulation are similar, suggesting that the distinct biochemical pathways merge into a common pathway before effecting degranulation.

Inhibitory effect of inhaled procaterol on anaphylactic bronchoconstriction and thromboxane A2 production in guinea-pigs

This study was designed to examine whether an inhaled beta 2-agonist, procaterol, inhibits thromboxane A2 (TXA2) production induced by antigen challenge in passively sensitized guinea-pigs in vivo. Antigen-induced bronchoconstriction was markedly inhibited by pre-treatment with procaterol. Inhaled procaterol significantly reduced in a dose-dependent manner the increment in TXB2 concentration in bronchoalveolar lavage fluid obtained 5 min after antigen challenge. Aerosol administration of procaterol significantly inhibited bronchoconstriction induced by inhaled histamine. These results suggest that inhalation of procaterol has an inhibitory effect on antigen-induced TXA2 production as well as a protective effect against bronchoconstriction induced by bronchoactive agents.

Pharmacology of airway inflammation in asthma

Chronic desquamative eosinophilic bronchitis is a characteristic pathologic feature of asthma which may even antedate the onset of symptoms. The pharmacology of asthmatic inflammation has been relatively poorly studied and most of the current data available have been inferred indirectly from studies of bronchial hyperresponsiveness and late-phase responses. Apart from mast cells, the effects of drugs used in the treatment of asthma on other airway inflammatory cells such as eosinophils, alveolar macrophages, etc. have not been extensively studied. The pharmacology of asthmatic inflammation should comprise the study of various aspects of this inflammatory response such as airway microvascular leakage, mediator release, and cell chemotaxis. Ultimately the pharmacologic modulation of the pathologic features of the asthmatic airway by the chronic use of antiasthma drugs, coupled with clinical responses, need to be investigated using bronchial biopsies and broncholveolar lavage in asthmatic patients.

Nedocromil sodium inhibits antigen-induced contraction of human lung parenchymal and bronchial strips, and the release of sulphidopeptide-leukotriene and histamine from human lung fragments

1. The effects of nedocromil sodium on antigen-induced release of sulphidopeptide-leukotrienes and histamine from passively sensitized fragments of human lung, and on antigen-induced contraction of sensitized strips of human lung parenchyma and bronchus, have been studied. 2. Nedocromil sodium 0.1 and 1 microM inhibited leukotriene release from fragments of human lung by 30% and 38% respectively, and histamine release by 43% for both concentrations, but 10 microM was ineffective. The lung fragments, which were passively sensitized to house dust mite, Dermataphagoides pteronyssinus, in control experiments released leukotrienes (6.58 +/- 0.12 nmol equiv. leukotriene C4 per g, n = 6) and histamine (10.3 +/- 1.8 of total tissue histamine, n = 5) when challenged with house dust mite extract. 3. Isolated strips of human lung parenchyma, passively sensitized to D. pteronyssinus, contracted when treated with house dust mite extract to a mean value of 40% of the maximal histamine response for each strip. Nedocromil sodium 0.1 and 1 microM inhibited these contractions by 50% and 70% of the control response, but 10 microM had no inhibitory effect. 4. Isolated rings from human bronchus, also passively sensitized to D. pteronyssinus, contracted when treated with house dust mite extract to a mean value of 86% of the maximal histamine response. Nedocromil sodium 1 microM, but not 0.1 or 10 microM, inhibited contractions by 48% of the control response. 5. The therapeutic effects of nedocromil sodium in allergic asthma may depend, partly, on its inhibition of antigen-induced release of leukotrienes and histamine in human lung and its consequent inhibition of antigen-induced contractions of parenchymal and bronchial tissue.

Salbutamol in the 1980s. A reappraisal of its clinical efficacy

Salbutamol (albuterol) is a beta 2-selective adrenoceptor agonist which accounts for its pronounced bronchodilatory, cardiac, uterine and metabolic effects. During the intervening years since salbutamol was first reviewed in the Journal (1971), it has become extensively used in the treatment of reversible obstructive airways disease. Numerous studies in this disease (including severe acute, childhood and exercise-induced asthma) have confirmed the bronchodilatory efficacy of salbutamol, and it has been shown to be at least as effective as most of the currently available bronchodilators, if not more effective. The onset of maximum effect of salbutamol is dependent on the formulation used and the route by which it is administered. In most patients inhaled salbutamol is a first-line therapy, since it offers rapid bronchodilation, usually relieving bronchospasm within minutes. Although oral salbutamol has often proved to be less efficacious than the inhaled formulation, it still affords clinically significant bronchodilation, and it is particularly useful in those patients unable to coordinate the use of inhalers. Parenteral formulations of salbutamol are generally reserved for the treatment of severe attacks of bronchospasm and they are one of the treatments of choice in these life-threatening situations. Studies of the concomitant use of salbutamol and other agents such as anticholinergics, methylxanthines and beclomethasone dipropionate have usually shown a complementary response in the majority of patients, as might be expected from the different mechanisms of action of these groups of drugs. Salbutamol is generally well tolerated and any side effects observed are a predictable extension of its pharmacology. Since the frequency of side effects is dose related, and therefore dependent on the route of administration, it is not surprising that they are much more common following intravenous and oral rather than inhalation therapy. Tremor, tachycardia and hypokalaemia are the most frequently reported adverse effects. After nearly 20 years of use, salbutamol is well established as a 'first-choice' treatment in reversible obstructive airways disease. Indeed, throughout this time many new bronchodilatory agents have been studied but none have proved more effective. Clinical evaluation of salbutamol in the treatment of premature labour, hyperkalaemia and cardiac failure awaits further studies, although to date some encouraging results have been reported.

Reflections on the mechanism(s) of action of sodium cromoglycate (Intal) and the role of mast cells in asthma

In this review, only a few questions concerning the mechanism(s) of action of sodium cromoglycate in asthma have been considered. The large number of cells and mediator pathways where sodium cromoglycate may have pharmacological effects are depicted. In addition to its mast cell effect, sodium cromoglycate is also inhibitory to macrophages, eosinophils, monocytes and platelets, which are all important components in the inflammatory response of asthma. From studies with bradykinin and sulphur dioxide it is also known that the drug can block afferent discharges along non-myelinated nerves. Although the ability of sodium cromoglycate to block late phase responses and acquired hyper-reactivity is not questioned, to what extent its therapeutic efficacy can be accounted for by actions on these leukocytes and reflex pathways is not known. When administered to patients with asthma, sodium cromoglycate results in symptomatic improvement, but there is still much to be learned about its mode of action.

Importance of beta 2-adrenoceptor stimulation in the suppression of intradermal antigen challenge by adrenaline

1. Seven atopic subjects received two injections of antigen and one of saline intradermally in the back on each of 4 separate days. They were pretreated with four different drug combinations: (a) adrenaline 0.3 mg subcutaneously over the deltoid muscle (b) subcutaneous adrenaline preceded by 5 mg of the specific beta 2-adrenoceptor antagonist ICI 118,551 orally (c) 8 mg of salbutamol orally (d) placebo. Tablets were given 2 h before and subcutaneous injections 15 min before the intradermal injections of saline and antigen. 2. The median flare response to intradermal low dose antigen and high dose antigen after pretreatment with adrenaline was 4% and 49% of the response seen following pretreatment with placebo (P less than 0.001). When adrenaline was preceded by ICI-118,551, the corresponding median flare responses were 2% and 44% (P less than 0.001) of the placebo response. The flare response after pretreatment with salbutamol was not significantly different from placebo. 3. Adrenaline suppressed the median weal response to the higher dose of antigen to 52% of the response after pretreatment with placebo (P less than 0.05). This suppression by adrenaline was blocked by pretreatment with ICI 118,551. The median weal response after the highest dose of antigen was suppressed by salbutamol to 66% of the response seen after placebo, although this was not significant even when a further three subjects were studied with either salbutamol or placebo.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of sodium cromoglycate and nedocromil sodium on histamine secretion from human lung mast cells

Sodium cromoglycate and nedocromil sodium produced a dose dependent inhibition of histamine secretion from human pulmonary mast cells obtained by bronchoalveolar lavage and by enzymatic dissociation of lung parenchyma. Both compounds were significantly more active against the lavage cells than against the dispersed lung cells, and nedocromil sodium was an order of magnitude more effective than sodium cromoglycate against both cell types. Tachyphylaxis was observed with the parenchymal cells but not with the lavage cells. Nedocromil sodium and sodium cromoglycate also inhibited histamine release from the lavage cells of patients with sarcoidosis and extrinsic asthma.

Effect of salbutamol and inhaled sodium cromoglycate on the airway and neutrophil chemotactic activity in "fog"induced bronchospasm

To investigate whether salbutamol and sodium cromoglycate (SCG) inhibit airway response and the associated mediator release induced by ultrasonic nebulation of distilled water (UNDW, "fog"), we measured the serum neutrophil chemotactic activity (NCA) during bronchial challenge with "fog" with and without premedication with placebo, salbutamol, or SCG in 10 subjects with asthma, in four sets of studies. To assess changes in airway caliber, we measured FEV1. To assess changes in NCA, we measured the maximal distance reached by neutrophils in a filter when neutrophils were challenged with the subject's serum in a Boyden chamber. Treatment with placebo did not change baseline FEV1 or serum NCA; however, FEV1 decreased and serum NCA increased (p less than 0.05) after inhalation of "fog". Treatment with SCG did not affect either FEV1 and baseline serum NCA. After inhalation of "fog", no significant bronchoconstriction nor NCA increase was observed in eight of 10 patients with maximal mean percent decrease in FEV1 of -4.26, SEM 0.99, and maximal mean percent increase in NCA of +8.6, SEM 5.28. In the two patients who developed a bronchoconstriction after challenge with SCG pretreatment, an associated significant increase in NCA was observed but did not affect baseline NCA. After inhalation of "fog", no significant decrease in FEV1 (maximal mean percent decrease FEV1, -6.71, SEM 0.17) nor significant increase in serum NCA (maximal mean percent increase NCA, +3.6, SEM 7.1) was observed in nine of 10 patients. After salbutamol, only one patient developed a bronchoconstrictive response to "fog" associated with a significant increase in serum NCA. These results suggest that both SCG and salbutamol may prevent the bronchoconstriction induced by "fog" by inhibiting mediator release.

Formalin sensitivity and differential staining of mast cells in human dermis

The characteristics of the human dermal mast cell population with respect to formalin fixation sensitivity, toluidine blue staining and alcian blue/safranin staining were studied. Thirty-seven specimens of normal human skin were bisected. One half was fixed in 10% neutral buffered formalin and the other in Carnoy's fixative. Sections were cut and stained with either toluidine blue or alcian blue/safranin. Significantly more mast cells were visualized with alcian blue/safranin than with toluidine blue. With both stains, only approximately 50% of the mast cells observed in the Carnoy's fixed tissue could be visualized in the formalin-fixed tissue. Alcian blue/safranin staining revealed three patterns of mast cell granule staining: mast cells containing only alcian blue-positive granules, mast cells containing only safranin-positive granules, and mast cells containing a mixture of alcian blue-positive granules and safranin-positive granules. Mast cells containing only alcian blue-positive granules constituted the majority of the dermal mast cell population and 73% of these mast cells were formalin-sensitive. Mast cells containing only safranin-positive granules and those containing a mixture of alcian blue-positive granules and safranin-positive granules showed no evidence of formalin sensitivity. The human dermal mast cell population, therefore, displays heterogeneity with respect to formalin fixation sensitivity and alcian blue/safranin staining. Dermal mast cells were visualized in significantly greater numbers in skin from the head compared with that from the body or limbs.

The effects of cremophor EL in the anaesthetized dog

The effects of cremophor EL were studied in 13 anaesthetized, paralyzed and ventilated dogs. Twenty per cent cremophor EL in a dose of 4.3 +/- 0.92 ml was infused at a rate of 30 ml X hr-1. In seven dogs, thoracopulmonary compliance, heart rate, systemic arterial pressure (SAP), pulmonary pressures (PAP, PCWP, RAP), cardiac output (CO) and platelet and white cell counts, were measured before the injection of cremophor EL, at the end of infusion and 5, 10, 30 and 150 minutes after the end of infusion. In six dogs, SAP, CO, and blood volume were measured before the injection of cremophor EL, at the end of infusion and 10, 30, 90 and 150 minutes after the end of infusion. Plasma histamine and catecholamines were assayed before the injection of cremophor EL and 2, 5, 10, 30, 90 and 150 minutes after starting the infusion. Cremophor EL induced a marked, sustained and significant decrease in SAP at the end of infusion and at 5, 10 and 30 minutes after the completion of the infusion (-68, -71, -70 and -43 per cent respectively), in PCWP, RAP and CO (-78 per cent at the end of infusion, -32 per cent 150 minutes after the end of infusion). Heart rate and systemic vascular resistance did not vary significantly. Pulmonary vascular resistance increased at the end of infusion, five and ten minutes after the end of infusion (+734, +548 and +439 per cent respectively). Plasma volume decreased 10 and 30 minutes after the end of infusion (-28 and -30.5 per cent respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of IgE-dependent histamine release from human dispersed lung mast cells by anti-allergic drugs and salbutamol

The ability of the anti-allergic drugs, sodium cromoglycate (SCG), lodoxamide, traxanox, RU31156 and the beta-adrenoceptor agonist salbutamol to inhibit IgE-dependent histamine and prostaglandin D2 (PGD2) release was assessed using human dispersed lung mast cells. The anti-allergic drugs were weak inhibitors of histamine release, high concentrations (100-1000 microM) producing less than 35% inhibition. Salbutamol produced 39% inhibition at 10 microM. The efficacy of both SCG and salbutamol was inversely related to the concentration of anti-IgE used for challenge and to the degree of histamine release. Rapid tachyphylaxis was observed with all anti-allergic drugs but not with salbutamol. Cross-tachyphylaxis was observed between SCG and the other anti-allergic drugs, suggesting a common mechanism of action. No cross-tachyphylaxis was observed between SCG and salbutamol. SCG was significantly (P less than 0.001) more effective in inhibiting PGD2 than it was histamine release. Preferential inhibition of PGD2 compared with histamine release was less marked (P less than 0.05) with salbutamol and not significant with the other anti-allergic drugs. Mast cells dispersed by enzymatic digestion of human lung released more histamine on immunological challenge than mechanically dispersed cells obtained by fine chopping of tissue. Enzyme treatment of mechanically dispersed cells removed this difference. Enzymatically and mechanically dispersed cells responded similarly to the inhibitory effects of SCG and salbutamol. Our results suggest that salbutamol is a more effective inhibitor of mediator release from human lung mast cells than anti-allergic drugs. However, with the low levels of mediator release achieved during an allergic reaction in man in vivo, both salbutamol and SCG are likely to be effective inhibitors of both preformed and newly generated mediators.

Cromolyn sodium: a review of mechanisms and clinical use in asthma

The cellular and clinical pharmacology of cromolyn sodium are reviewed. Cromolyn sodium inhibits the release of mediators of inflammation, induced by specific antigens as well as nonspecific mechanisms, such as exercise, from mast cells. Cromolyn may also inhibit the activity of other cell types that produce inflammation. It is the only antiasthmatic that blocks both early and late asthmatic responses induced by allergen inhalation and exercise. Consequently, cromolyn therapy can block the increase in bronchial hyperreactivity induced by chronic allergen exposure. Cromolyn is effective for controlling the symptoms of mild to moderate chronic asthma in 60 to 70 percent of patients. In comparative studies, cromolyn has been as effective as theophylline for controlling symptoms of chronic asthma with fewer side effects, and may be particularly suited for asthmatic patients with learning or behavioral problems. The combination of theophylline and cromolyn is often more effective than either agent alone. Because of the convenience of administration, cromolyn is preferred over theophylline for exercise-induced asthma. Cromolyn may allow the corticosteroid dosage to be reduced in severe steroid-dependent asthmatics, but it is primarily indicated for the prophylaxis of mild to moderate disease. Adverse reactions to cromolyn are uncommon to rare. Cromolyn is now available in a Spinhaler, a metered-dose aerosol, and a nebulizer solution. If taken properly all preparations appear to be equally effective. Attention to proper inhalation technique and appropriate education of the patient is essential to ensure a good outcome with cromolyn.

The mediators of allergic contraction of human airway smooth muscle: a comparison of bronchial and lung parenchymal strip preparations

Antigen-induced contractions of passively sensitized preparations of human bronchi and lung parenchymal strips were studied. Mepyramine did not affect the magnitude or time course of the contractile responses of either preparation. Indomethacin potentiated the responses of lung parenchymal strips, but inhibited those of bronchial preparations. Responses of both tissues were inhibited by the leukotriene antagonist FPL 55712, by the lipoxygenase inhibitor BW 755C, and by the anti-allergic compound disodium cromoglycate Disodium cromoglycate and BW 755C inhibited histamine release from lung parenchymal strips. The results indicate an important role for leukotrienes in allergic contraction of both large and small human airways, while histamine is of little importance. Bronchoconstrictor prostaglandins may also contribute to the response of large airways.

Pulmonary anti-anaphylactic activity of clenbuterol tested on actively and passively sensitized guinea-pigs

Clenbuterol, an adrenergic beta-mimetic agent free of cardiostimulant effects, prevents the release of histamine from isolated rat mast cells. We studied its anti-anaphylactic activity in guinea-pigs and compared it with that of isoprenaline. At doses inactive against the bronchoconstriction caused by 5HT, clenbuterol (3 micrograms/kg) and isoprenaline (0.1-0.3 micrograms/kg) prevented the bronchoconstriction due to 1 mg/kg ovalbumin infused into passively sensitized animals. Clenbuterol and isoprenaline (0.5-1 microM) inhibited by 40% the contractions of superfused parenchyma lung strips from actively sensitized animals, stimulated with 0.3, 1 and 10 micrograms of ovalbumin. When strips from passively sensitized animals were challenged in the organ bath, clenbuterol and isoprenaline (0.01 microM) reduced by 50% the contraction triggered by 10 micrograms/ml of ovalbumin. These concentrations of clenbuterol were ineffective against contractions caused by acetylcholine. Clenbuterol and isoprenaline (0.001-0.01 microM) inhibited the release of histamine and of thromboxane A2 triggered by ovalbumin (0.1, 1 and 10 micrograms) injected into isolated lungs from actively sensitized guinea-pigs indicating that the anti-anaphylactic properties of clenbuterol are independent from its smooth muscle relaxing activity.

Histamine secretion from human skin slices induced by anti-IgE and artificial secretagogues and the effects of sodium cromoglycate and salbutamol

Human cutaneous mast cells show functional differences from their counterparts in other tissues. Following passive sensitization with 1% atopic serum for 30 min at 37 degrees C human skin slices released histamine after challenge with anti-human IgE in a concentration dependent manner. Maximum release of 14 +/- 2% was achieved with a 1/10 dilution of anti-IgE. Passive sensitization with 10% atopic serum increased the secretory response to anti-IgE but histamine release was only concentration related over the entire 1/1000 to 1/10 dilution range in half of the specimens studied, the remainder showing high dose tolerance to anti-IgE. Negligible histamine release occurred with anti-IgE challenge of slices which had not been passively sensitized. The histamine releasing ability of A23187 in human skin slices was similar to that observed in lung and adenoidal mast cells being concentration dependent over the range 0.1-3 microM with a maximum release of 25 +/- 3%. In contrast to human lung and adenoidal mast cells, poly-L-lysine and compound 48/80 induced histamine release from skin slices. Poly-L-lysine induced a concentration-dependent release of histamine over the range 0.01-10 microM with a maximum of 27 +/- 3%. The response to compound 48/80 was variable, releasing in some but not all specimens. Histamine release caused by anti-IgE, A23187 and poly-L-lysine was shown to be dependent upon extracellular calcium while release stimulated by compound 48/80 was calcium independent. The chemotactic peptide, formyl-methionyl-leucyl-phenylalanine, over the range 0.01-10 microM failed to release histamine from skin slices.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of histamine release from dispersed human lung and tonsillar mast cells by nicardipine and nifedipine

Calcium entry blocking drugs attenuate antigen-induced bronchoconstriction in asthma which is mast cell mediated. We have investigated the effects of two calcium uptake blockers, nicardipine and nifedipine on histamine secretion from human mast cells dispersed from lung and tonsillar tissue. Mast cells were activated for secretion with anti-human IgE or calcium ionophore, A23187. Nicardipine and nifedipine caused a concentration-related inhibition of IgE-dependent histamine release from both lung (IC30 10 microM and 4.4 microM) and tonsillar (IC30 21 microM and 47 microM) mast cells. Nicardipine and nifedipine also inhibited mast cell histamine release induced by A23187 with IC30 values of 14 microM and 67 microM for lung and 15 microM and 30 microM for tonsillar mast cells. In the absence of drugs, increasing the extracellular calcium concentrations from 0.2 to 5 mM caused a concentration related increase in IgE-dependent histamine release from tonsillar mast cells. Both nicardipine and nifedipine (50 microM) displaced the concentration-effect curve to the right. Nicardipine (0.01-100 microM) caused a concentration related inhibition of rat kidney histamine methyltransferase activity used in the radioenzymatic assay of histamine (ki of 7.5-12 microM) whereas nifedipine was only a weak inhibitor. Nicardipine also interfered with the spectrofluorimetric assay after exposure to ultraviolet light. These observations demonstrate that nicardipine and nifedipine inhibit IgE-dependent and ionophore stimulated mediator secretion from human mast cells. The lack of stimulus-related specificity and the high drug concentrations required suggest that classical calcium channel blockade is not responsible for inhibition of mast cell mediator release. Furthermore, we suggest that inhibition of mast cell mediator release is unlikely to be the mechanism by which these drugs alleviate asthma.

Bronchorelaxation and plasma histamine after salbutamol inhalation

Plasma histamine in 8 normal subjects was measured before and after inhalation of carbachol to induce a 50% fall in specific airway conductance (SGaw). The measurements were repeated 5 min after inhalation of salbutamol or placebo. No significant change in plasma histamine occurred after placebo or carbachol inhalation, despite the persistent induced bronchospasm after the latter treatment. In contrast, plasma histamine was significantly increased from 0.25 to 0.43 ng/ml after salbutamol inhalation. Simultaneously, induced bronchospasm was relieved, from 51% to 103% of baseline SGaw. Thus, the relief of carbachol-induced bronchospasm by salbutamol was associated with a rise in plasma histamine. Since salbutamol itself is a potent inhibitor of mast cell degranulation and histamine release, the present findings suggest that histamine may be released and sequestered within the lungs during carbachol-induced-bronchospasm, and also that desequestration of bronchoconstrictor mediators accumulated at the point of contact of bronchial smooth muscle may contribute to the relief of bronchospasm by salbutamol.

Use of calcium channel blocking agents in the management of childhood asthma

The function of the cells involved in the genesis of bronchial asthma is calcium dependent. The "Ca2+ hypothesis of asthma" suggests that calcium channel blocking agents may have a beneficial effect in asthma. The clinical trials with the available classic calcium antagonists in childhood asthma are very few and their clinical application remains to be determined. Sodium cromoglycate and ketotifen, which have been in clinical use for many years, can be considered as calcium channel blockers and seem to have a significant role in the prophylaxis of bronchial asthma.