Inhibitory effect of calcium antagonists on histamine release from human leukocytes. In vivo and in vitro experiments

Calcium, calcium channel blockade and airways function

This review will highlight recent advances in understanding the physiological role of calcium and effects of calcium channel blockers on pathogenetic factors in asthma, including airway smooth muscle contraction, mast cell degranulation and mucus secretion. A review of clinical studies with calcium channel blockers in asthma will also be presented.

Ionic regulation of human basophil releasability. II. Non-releasing basophils are converted into releasing basophils in a low-Na+ medium

The effects of different extracellular Na+ and Ca2+ concentrations on histamine release from human basophils were investigated. Isosmotic replacement of extracellular Na+ either with choline+, a non-permeant Na+ analogue, or glucose significantly increased spontaneous and anti-IgE-induced histamine release. Basophils from 12 of 49 normal subjects, which were found not to release histamine upon challenge with an optimal dose of anti-IgE in a 135 mM NaCl buffer, were converted into releasing basophils when stimulation with anti-IgE was performed in a low-Na+ medium. The increase in Na+ concentration in the extracellular medium was accompanied by a reduction in the magnitude of basophil response to anti-IgE, which was significantly more pronounced in non-releasers than in releasers (per cent inhibition by 70 mM NaCl 75.5 +/- 3.2 vs 43.5 +/- 9.0, P < 0.01). At higher Na+ concentrations a progressive and almost complete abrogation of histamine release was observed in non-releasers, but not in releasers (maximal per cent inhibition at 140 mM NaCl 97.3 +/- 1.3 vs 50.4 +/- 8.6). The Na+/H+ exchanger monensin had a dose-dependent inhibitory effect on anti-IgE-induced histamine release, and the concentration inhibiting 50% of histamine release was 1.5 x 10(-7) M. When basophils were challenged in the presence of different Na+ and Ca2+ concentrations, it was shown that the two cations have antagonistic effects, which is to say that they down-regulate and upregulate histamine release, respectively. Moreover, the requirement of extracellular Ca2+ was lowered in a low-Na+ medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of human basophil activation. IV. Dissociation between cationic dye binding and histamine release: role of Ca2+ ions

In previous studies we observed that in vitro histamine release from human basophils could be dissociated from the loss of affinity of basophil granules for a cationic dye, toluidine blue. In the present study we further explored the intracellular signals leading to the decrease in toluidine blue positive basophil (TB+) numbers, with or without histamine release. Since Ca2+ mobilization is a crucial event in secretion and particularly in histamine release, we studied the role of Ca2+ in histamine release as compared to TB+ decrease. In the presence of external Ca2+ (2 mM): i) Ca2+ channel antagonists verapamil and nifedipine up to 10 microM were without effect on IgE-mediated histamine release and TB+ decrease; ii) loading of the leucocytes with Quin2 or preincubation with TMP-8, an internal Ca2+ antagonist, significantly inhibited the release of histamine and the decrease of TB+ basophils. In the absence of added external Ca2+:i) histamine release was abolished whereas the decrease of TB+ was not modified, even in the presence of EGTA;ii) the decrease of TB+ could be inhibited by prolonged EGTA preincubation, by Quin2 loading and incubation with TMB-8. We conclude that histamine release requires both external Ca2+ influx and mobilization of internal Ca2+. In contrast, no influx of external Ca2+ is required for TB+ decrease in which, however, internal Ca2+ mobilization appears to play an important role.

The determination of histamine in challenged human leukocyte preparations by high-performance liquid chromatography

A highly sensitive and rapid method was developed for the determination of histamine in challenged human leukocyte preparations by high-performance liquid chromatography. The assay is based on the Shore's OPT-reaction of the unpurified sample and on a specific separation of the derivate with analytical reversed phase phenyl column combined with spectrofluorometric detection. The detection limit of histamine by this method was 0.07 pmol (signal to noise ratio 2:1) and the within-day variation for peak height was 3.6% and for retention time 0.8%. A good linear standard curve ranging from 12.5 pg to 500 pg (0.07 pmol-2.7 pmol) was obtained with correlation coefficient of 0.998. The histamine release from human basophils in mixed leukocyte preparation was induced by the calcium ionophore A 23187. A concentration of 0.4 micrograms/ml ionophore was required for 50% histamine release with a Ca2(+)-concentration of 1.8 mmol/l. The measured total histamine content was 1.5 pg/basophil.

The role of calcium antagonists in bronchial reactivity

Calcium (Ca) ions play an important pathophysiologic role in allergic reactions. Thus, mediator release from mast cells, synthesis of some newly formed chemical mediators, airway smooth muscle contraction, and nerve-impulse conduction are all dependent on the availability and flux of Ca ions. It is likely, therefore, that Ca antagonists would modify allergic bronchoconstriction. In vitro, Ca antagonists have been demonstrated to inhibit mediator release (histamine, slow-reacting substance of anaphylaxis, and platelet-activating factor) from mast cells, passively sensitized human lung fragments, and leukocytes. Ca antagonists have also been found to inhibit synthesis of leukotrienes in rat lungs and cyclooxygenase products in sheep, possibly by inactivating phospholipase A2 and/or 5-lipoxygenase. In addition, nifedipine, verapamil, and gallopamil have demonstrated inhibition of airway smooth muscle contractions to histamine, carbachol, and antigen in various species. In vivo effects of Ca antagonists are variable, depending on the species, experimental design, the stimulus or the agonist, and the Ca antagonist used. Animal studies have demonstrated the inhibition of histamine, methacholine, citric acid, and prostaglandin F2 alpha-induced bronchoconstriction in guinea pigs and dogs by intravenous nifedipine. In contrast, verapamil inhibited antigen-induced bronchoconstriction in allergic sheep without any effect on histamine- and carbachol-induced responses. Ca antagonists (nifedipine and verapamil) have been of limited value in human subjects and generally have no significant bronchodilating activity. Both nifedipine and verapamil prevent the exercise-induced asthma and partly attenuate the histamine and methacholine-induced bronchoconstriction. Oral nifedipine is generally more effective than oral verapamil against acute antigen-induced bronchoconstriction; however, this efficacy may be limited by systemic side effects. Inhaled Ca antagonists may be more effective and free of systemic side effects, as demonstrated by greater efficacy of inhaled verapamil. A new Ca antagonist, gallopamil (a methoxy derivative of verapamil), is being investigated as an aerosol, and preliminary studies in animals and humans have found it fourfold to seventeenfold more potent than verapamil. In sheep, gallopamil has been found to attenuate histamine, carbachol, and platelet-activating factor-induced bronchoconstriction, as well as to inhibit early and late-phase allergic airway responses. Studies in human subjects have also demonstrated the inhibition of antigen-induced bronchoconstriction by inhaled gallopamil, with efficacy comparable or better than cromolyn sodium.(ABSTRACT TRUNCATED AT 400 WORDS)

Comparison of the action of calcium antagonists on basophil histamine release

The inhibitory capacity of calcium antagonists on basophil histamine release was examined in allergic patients and in controls. All dihydropyridines tested (nifedipine, nimodipine, nitrendipine, nicardipine, felodipine) dose-dependently inhibited anti-IgE- and A23187-induced release with an order of potency of felodipine greater than nicardipine greater than nifedipine = nimodipine = nitrendipine. Only the inhibition induced by felodipine and nicardipine on anti-IgE-induced release could be counteracted by increasing extracellular calcium. Diltiazem, not belonging to the dihydropyridines, was a weak inhibitor. A combination of felodipine and verapamil in low concentrations exerted a synergistic inhibitory effect on histamine release, whereas this was not the case with other combinations of antagonists. The results suggest differences in the mode of action of the 1.4-dihydropyridines. This might be of significance in the search for calcium antagonists suitable in the treatment of allergic diseases.

Calcium antagonists in the management of asthma: breakthrough or ballyhoo?

Research demonstrating the importance of intracellular calcium regulation in each of the pathophysiologic events of asthma has lead to speculation that calcium antagonists may be beneficial in the treatment of reactive airways disease. A plethora of data has been generated on the effects of verapamil, diltiazem, nifedipine, and several investigational agents on experimentally induced asthma, indicating that none of these agents significantly affects resting bronchomotor tone, and their efficacy in preventing bronchospasm is a function of the drug, dose, route of administration and method of bronchoprovocation. Most studies have demonstrated calcium antagonists have only modest and highly variable effects on airway smooth muscle contraction. Additional studies are needed to define the effects on the inflammatory component of airways obstruction, steroid requirements in steroid-dependent patients, and on the alteration of the pharmacodynamics of other agents used for the management of chronic asthma.

Effect of nitrendipine on histamine release from human basophil leukocytes

The effect of the new calcium antagonist nitrendipine on in vitro basophil activation was evaluated in 10 subjects. The histamine release induced by calcium ionophore A23187, f-met peptide and anti-IgE was inhibited, in a dose-dependent fashion, by nitrendipine in the concentration range of 1-100 microM. The activity of this calcium antagonist seems complex and related to an interference with calcium at multiple sites. At concentrations higher than 200 microM, nitrendipine causes histamine release from basophil leukocytes. This histamine secretion is likely to be due to a cytotoxic effect, since it is associated with an increase in LDH levels in the cell supernatant.

Membrane sialic acid influences basophil histamine release by interfering with calcium dependence

The influence of the cell membrane content of sialic acid on basophil histamine release was examined in vitro in allergic patients and normal controls. Enzymatical removal of sialic acid enhanced histamine release induced by allergen and anti-IgE, whereas an increase in membrane sialic acid content by insertion of sialic acid containing gangliosides into the membrane inhibited the mediator release. The reduction in membrane sialic acid content abolished the inhibitory capacity of the calcium channel antagonist nimodipine, whereas the inhibition produced by verapamil and lanthanum was not affected. This difference, together with the previous finding that alterations in membrane sialic acid content is reflected in the cell sensitivity to extracellular calcium, suggest an interaction between membrane sialic acid and the calcium channels involved in basophil histamine release.

Influence of nimodipine, verapamil and lanthanum on histamine release from human basophils: effect of pretreatment with sialidase

Our previous studies suggest that the membrane content of sialic acid influences histamine release from human basophils by interfering with the transmembraneous calcium fluxes preceding histamine release. In this study we investigated a possible interaction between membrane sialic acid and the calcium channels, using the calcium antagonists nimodipine, verapamil and lanthanum. Anti-IgE-induced histamine release was inhibited by verapamil, nimodipine and lanthanum. When cells were pretreated with sialidase in order to remove sialic acid from the cell membrane, the inhibitory action of nimodipine was abolished, whereas the inhibition by verapamil or lanthanum was unaffected. This difference may be explained by the different mode of action of the calcium channel antagonists, and the results suggest an association between membrane sialic acid and the calcium channel.

Effect of calcium antagonists on histamine release from human basophil leukocytes

The effect of calcium antagonists on basophil activation was investigated in 14 subjects. Verapamil, methoxyverapamil and diltiazem, in a concentration range of 1-100 microM, exert a concentration-dependent inhibition on the human basophil histamine release induced by calcium ionophore A23187, zymosan activated human serum and grass pollen allergens. This inhibitory effect is highly variable from subject to subject and from drug to drug. At concentrations higher than 200 microM, verapamil, methoxyverapamil and diltiazem induce a calcium independent histamine secretion from basophil leukocytes. This mediator release is associated with an increase in LDH levels in the cell supernatant and seems to be due to a cytotoxic effect.

Calcium antagonists in mania: a double-blind study of verapamil

Five of seven acutely manic patients improved significantly when taking verapamil but not placebo in a double-blind crossover study. This finding adds support to two other formal studies of verapamil, several case reports of verapamil in manic patients, and one small study of nifedipine suggesting that some calcium antagonists may have antimanic properties. Indirect evidence links this antimanic action to correction of a disturbance of intracellular calcium dynamics in affective disorders. However, the effectiveness of calcium antagonist drugs could also be related to some property other than interference with the action of calcium within brain neurons.

Heterogeneity of calcium channels in mast cells and basophils and the possible relevance to pathophysiology of lung diseases: a review

Calcium plays a critical role in the formation and secretion of a wide variety of chemical mediators. Calcium slow-channel blockers, e.g. nifedipine and verapamil, have been shown to inhibit the synthesis of SRS (SRS-A, leukotrienes) in human and guinea pig lung tissue, thromboxane A2 formation in rat lung and platelet activating factor in human neutrophils. Verapamil and nifedipine also prevent the release of lysosomal enzymes from rabbit and human polymorphonuclear neutrophils. Calcium-channel blockers produce variable inhibitory effects on allergic and nonallergic histamine secretion. Ca++-entry blockers also inhibit the Ca++ uptake (influx) into mast cells. Many of these inhibitory effects of Ca++ antagonists are antagonized by an increased extracellular Ca++ ion concentration. The magnitude of the inhibitory influences of Ca++-channel blockers on allergic and nonallergic release of chemical mediators appears to depend on the cell source, species, nature and the concentration of the secretory stimuli as well as on the composition and pH of buffers and the concentration of Ca++-entry blockers used. The data summarized in this review suggest the existence of a functional heterogeneity of Ca++ channels in leukocytes, mast cells and basophils. Interference with the Ca++-dependent steps involved in the formation and/or release of chemical mediators appears to be the primary mode of action for Ca++-channel blockers in these cells. The differential effects of Ca++ antagonists on Ca++-dependent activation of phospholipase A2,5-lipoxygenase, and calmodulin (or other intracellular Ca++-binding proteins) in different cell types (mast cells, basophils, leukocytes, lung tissue, etc.) may explain the variation of their effectiveness in inhibiting the synthesis/release of chemical mediators and antagonizing bronchoconstriction in response to diverse stimuli. During the process of hypersensitization and in immediate hypersensitivity diseases, Ca++ homeostasis (uptake, mobilization, distribution, relocation, etc.) may be altered in leukocytes (mast cells, basophils) and lung tissues. The altered Ca++ homeostasis could be responsible for the induction of airway hyperreactivity in asthmatics and for hyperreleasability of chemical mediators from leukocytes, mast cells and other cell types.(ABSTRACT TRUNCATED AT 250 WORDS)

Failure of Verapamil in inhibiting allergen-induced histamine release in vivo

In order to evaluate the effect of Verapamil on human cutaneous anaphylactic responses, ragweed-sensitive individuals were skin tested with ragweed, ragweed plus Verapamil, and Verapamil alone. In addition, using a skin chamber technique, the effect of Verapamil on antigen-induced histamine release in vivo was investigated. The results suggest that Verapamil, applied locally in non-irritant doses, does not affect Type I hypersensitivity skin reactions.

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.

Inhibitory effect of cyclosporin A on histamine release from human leukocytes and rat mast cells

The influence of cyclosporin A (CyA) on human basophil histamine release induced in vitro by specific antigen, anti-IgE, calcium ionophore A23187, or concanavalin A (Con A) was studied. CyA inhibited the release induced by these four stimulators. It is suggested that the drug acts directly on the target cell, since similar effect was obtained with isolated peritoneal rat mast cells. The basophil histamine release was not changed by a non-immunosuppressive cyclosporin derivate.

Role of calcium in arachidonic acid-induced contractions of guinea pig airways

We have previously shown that arachidonic acid (AA)-induced contractions of indomethacin-pretreated guinea pig trachea and parenchyma are due to the synthesis of leukotrienes C4 and D4. The present experiments were designed to investigate the role of calcium (Ca2+) in the above. AA (66 microM)-induced contractions of trachea, but not parenchyma, were reduced in Ca2+-free Krebs-Henseleit solution ( KHS ). However the contractions of both trachea and parenchyma were abolished in Ca2+-free KHS with either lanthanum chloride (1 mM) or EDTA (300 microM). The Ca2+ antagonists, verapamil (100 microM), nitrendipine (100 microM), and TMB-8 (100 microM), reduced AA-induced contractions of both trachea and parenchyma. Re-addition of Ca2+ (2.2 mM) to trachea and parenchyma in Ca2+-free KHS in the presence of lanthanum restored the AA-induced contractions. This effect of Ca2+ was reduced by verapamil (100 microM) or nitrendipine (100 microM). LTC4-induced contractions of trachea and parenchyma were unaffected by nitrendipine (100 microM), whereas tracheal contractions were reduced in Ca2+-free KHS . Both tracheal and parenchymal contractions to LTC4 were reduced in Ca2+-free KHS in the presence of lanthanum chloride (1 mM). We conclude that superficially bound pools of Ca2+ are important in AA-induced contractions of the airways. Furthermore, nitrendipine reduces AA-induced contractions by inhibiting AA metabolism and not by inhibiting airway smooth muscle contraction induced by released leukotrienes.