Dual effect of magnesium on compound 48/80-induced histamine secretion from rat peritoneal mast cells.

The effect of magnesium on the secretory response to compound 48/80 from rat peritoneal mast cells was studied. The decrease in secretion caused by calcium deprivation was enlarged by magnesium. Glucose partially counteracted the decrease caused by calcium deprivation but not the one caused by magnesium. The addition of calcium to the cells simultaneously with compound 48/80 completely restored the secretory response if magnesium was present. The response was only partially restored in a magnesium- and glucose-free medium, whereas it was almost completely restored if glucose was present. Magnesium had a considerable effect on the restoration of the secretory response of EGTA-treated cells, whereas the effect of glucose was minimal indicating that an effect on the energy metabolism was of minor importance. The secretory response could also be restored by an exposure of the cells to calcium prior to stimulation with compound 48/80. This was, however, only observed if magnesium was present and glucose had no effect. The influence of magnesium on the restoration of the secretory response may partly occur by an effect on the energy metabolism, partly by an effect on the stimulus-secretion coupling. We propose that insufficient supply of Mg2+ to the G-protein during activation by compound 48/80 might cause a suboptimal signal transduction.     

Sodium-potassium ATPase inhibition potentiates compound 48/80-induced histamine secretion from mast cells.

The effect of ouabain on the histamine secretion induced by compound 48/80 has been studied using rat peritoneal mast cells. Ouabain did not modify histamine release in the presence of millimolar concentrations of extracellular calcium. However, when mast cells were previously washed with a calcium-free buffer, ouabain strongly potentiated histamine release elicited by compound 48/80. The full potentiation of mast cell secretion by ouabain required 30 min preincubation before adding compound 48/80. It was inhibited by lanthanum and EGTA. Potassium deprivation mimicked the effect of ouabain. A 30 min preincubation time without potassium was also required. Potassium concentrations below 2.7 mM increased the effect of ouabain whereas higher potassium concentrations reversed this effect. The potentiation of compound 48/80-induced histamine release by ouabain or potassium deprivation was not immediately reversed by washing away ouabain or by adding potassium, respectively. The data confirm that sodium-potassium ATPase is involved, through a calcium-dependent process, in the regulation of histamine release from mast cells.     

Compound 48/80 and substance P induced release of histamine and serotonin from rat peritoneal mast cells

The effect of substance P and compound 48/80 on histamine and serotonin release from not isolated and isolated mast cells have been compared in experiments in vitro. The response of not isolated and isolated mast cells were virtually identical. The release of both amines, in response to 48/80 and substance P, was dose-dependent. The percentage of histamine released by 48/80 was significantly higher than the percentage of serotonin, the difference being higher at lower concentrations of compound 48/80 after 15 min of incubation. Substance P also showed a tendency to higher efficiency for histamine than for serotonin release. In contrast to 48/80, the dose-response curves for histamine and serotonin release were parallel. These results support the view that the ratio between histamine and serotonin release depends on the liberator used. They also showed that this ratio can depend on the concentration of the agent inducing secretion. The results indicate that substance P as well as 48/80 act rather selectively as histamine liberators and that there is some difference in releasing properties of 48/80 and substance P.     

Canatoxin triggers histamine secretion from rat peritoneal mast cells.

Canatoxin, a toxic protein present in the seeds of Canavalia ensiformis, induces the secretion of serotonin, dopamine and insulin through activation of the lipoxygenase pathway. The purpose of the present study was to verify if canatoxin causes histamine release from rat peritoneal mast cells and to perform a detailed study of this phenomenon. Our results indicate that canatoxin is capable of activating mast cells to release histamine. The process is time- and concentration-dependent, occurs without cell damage and requires metabolic energy as well as the presence of divalent cations (Ca2+ and Mg2+). Optimal release occurs at 37 degrees C and at physiological pH. Extremes of temperature (0 degree C and 45 degrees C) inhibit the process. We conclude that canatoxin induces histamine release from rat peritoneal mast cells by an active secretory process.     

Inhibitory activity of indolin-2-one derivatives on compound 48/80-induced histamine release from mast cells

Four alkaloids, previously identified in Isatis species, were tested for their inhibitory effect on histamine release. Whereas tryptanthrin, indirubin and deoxyvasicinone did not inhibit histamine release, the effect of indolin-2-one exceeded that of the mast cell stabilizing drug disodium chromoglycate.     

Effect of lanthanide ions on histamine secretion from rat peritoneal mast cells.

1 Ions of the lanthanide series (lanthanum-lutetium) inhibit histamine release induced by allergen and anti-IgE in the presence of extracellular calcium. The inhibition is dose-dependent in the range 10(-6) to 10(-9) M and there is no marked difference in potency between the lanthanides. 2 The response to lanthanum is biphasic and higher concentrations (10(-4) M) potentiate the release. Maximal concentrations (10(-3) M) again abolish secretion. 3 The effect of concanavalin A is weakly antagonized by lanthanum but strongly inhibited by higher lanthanides. 4 Inhibition of histamine release evoked by basic agents is markedly dependent on the ionic radius of the lanthanide. In the presence of extracellular calcium, dysprosium is the most effective inhibitor. Similar results are observed with dextran. In the absence of calcium, there is a regular increase in inhibition with decreasing ionic radius. 5 Inhibition of release in the presence of calcium is immediate and does not require preincubation with the lanthanide. The antagonism due to lanthanum is competitive and the pA2 values vary with the secretagogue. In contrast, the inhibitory effect in the absence of extracellular calcium increase progressively with time. 6 These results are discussed in terms of the calcium-pools important in histamine release and the mode of action of different secretagogues.     

Calcium antagonists and histamine secretion from rat peritoneal mast cells

The calcium antagonists verapamil and nifedipine inhibited histamine release induced from rat peritoneal mast cells by a number of secretory stimuli. However, the concentrations required were much higher than those active in smooth muscle preparations. The inhibition was unaffected by elevated levels of external calcium and the drugs prevented release in the absence of added calcium. The novel calcium antagonist, PY 108-068, had no effect on histamine secretion from mast cells. These results suggest that calcium channels in the mastocyte may differ from those in smooth muscle and that at concentrations required to inhibit secretion, verapamil and nifedipine may have non-specific stabilizing effects on the mast cell membrane.     

Binding of active components of compound 48/80 to rat peritoneal mast cells

The binding characteristics of compound 48/80 were examined using rat mast cells and fractionated 14C-labeled compound 48/80 components at 4 degrees C in vitro where no degranulation of the cells occurred. The binding potencies of these components in the presence of Ca2+ generally paralleled their histamine releasing activities, except in the case of fractions G (decamer) and H (nonamer), both Ca2+-independent releasers, for the binding of which Ca2+ was inhibitory. Scatchard analyses and displacement studies indicated that the mast cells had two types of binding sites with high and low affinities for fractions D (tridecamer, Ca2+-dependent releaser, Kd = 3.41 X 10(-8) M and 3.35 X 10(-6) M) and H (Ca2+-independent releaser, Kd = 1.11 X 10(-7) M and 9.11 X 10(-6) M), respectively. These sites partially overlapped each other, and also the fraction D site partially overlapped the IgE site and the fraction H site overlapped the neurotensin or substance P site.     

On the mechanism of dextran-induced histamine secretion from rat peritoneal mast cells

The mechanism of histamine release induced from isolated rat peritoneal mast cells by clinical dextran was examined in detail. The putative involvement of cell-fixed IgE antibodies in the process was discounted by a number of experimental approaches. Instead, the characteristics of the release were found to be consistent with the interaction of the polysaccharide with specific glucoreceptors on the mast cell membrane.     

Calcium dependency of inhibition by arachidonic acid of compound 48/80-induced histamine release from mast cells

Compound 48/80 ( compd 48/80)-induced histamine secretion from rat mast cells was inhibited almost completely by pretreatment of the cells at 37 degrees with 25 microM arachidonic acid in the presence of 1.8 mM Ca2+. As the Ca2+ concentration was reduced below 1.8 mM, 25 microM arachidonic acid became less inhibitory and, then, progressively more stimulatory for histamine release with or without compd 48/80. No additive effect on histamine release was obtained by combining compd 48/80 and arachidonic acid. Pretreatment of mast cells with lidocaine, an inhibitor of Ca2+ binding to phospholipid, or with nordihydroguaiaretic acid, an inhibitor of Ca2+ flux and lipoxygenase, stimulated arachidonic acid-induced histamine release. Arachidonic acid also inhibited a compd 48/80-induced spike increment of intracellular 45Ca2+ uptake and a decrease of total 45Ca2+ uptake by 45Ca2+-preloaded mast cells. Arachidonic acid and Ca2+ also suppressed melittin-induced histamine release and compd 48/80-induced release of radioactivity from mast cells preloaded with [3H]arachidonic acid. These results suggest that exogenous arachidonic acid or its metabolite(s) may interact with membrane-associated Ca2+, disturbing Ca2+ availability for the trigger mechanism of compd 48/80-induced histamine release or inhibiting the subsequent metabolism of arachidonic acid via the lipoxygenase pathway to form active metabolites involved in the histamine liberating mechanism.     

Utilization of adenosine triphosphate in rat mast cells during and after secretion of histamine in response to compound 48/80

The adenosine triphosphate (ATP) content of rat mast cells and their lactate production were measured during and after secretion of histamine induced by compound 48/80. Antimycin A and oligomycin were used to block oxidative ATP synthesis, and 2-deoxyglucose (2-DG) was used to block glycolytic ATP synthesis. Histamine secretion was completed after 10 sec. exposure of the cells to compound 48/80. During that time period there was an increased ATP-utilization of 0.15 pmol/10(3) cells. After completion of the secretory process there seemed to be an enhanced utilization of ATP of 0.40 pmol/10(3) cells/min., which may be associated with recovery of the cells.     

A comparative study of histamine secretion from rat peritoneal and pleural mast cells

The effects of various histamine liberators and inhibitors on isolated rat peritoneal and pleural mast cells have been compared. The pleural cells showed an increased reactivity to challenge with antigen following passive, but not active, sensitization and were more responsive to challenge with anti-IgE. Phosphatidyl serine enhanced the secretion from both cell types. Peritoneal and pleural cells exhibited virtually identical responses after treatment with chemical secretagogues in the presence of exogenous calcium, but the peritoneal cells were significantly more reactive to stimulation with basic inducers in the absence of the cation. Anaphylactic histamine secretion was comparably inhibited by a number of anti-allergic drugs but the peritoneal cells were rather more sensitive to inhibition by dibutyryl cyclic AMP. These results are discussed in terms of the general functional heterogeneity of mast cells from different sources.     

Effect of dantrolene on histamine release from rat peritoneal mast cells.

Dantrolene strongly and dose-dependently inhibited histamine release from rat peritoneal mast cells induced by anti-IgE. Dantrolene inhibited Ca(2+)-mobilization from intracellular Ca(2+)-store as well as histamine release in mast cells activated by anti-IgE, the effect on both these phenomena being closely correlated. These results suggested that the effect of dantrolene on histamine release from rat mast cell might be due to the inhibition of Ca(2+)-release from intracellular Ca(2+)-store.     

A comparison of histamine secretion from peritoneal mast cells of the rat and hamster

Functional mast cells have been obtained by peritoneal lavage of the rat and hamster. Both cell types released histamine on stimulation with appropriate dilutions of anti-rat IgE and anti-hamster serum. The maximum response evoked by each reagent was significantly greater for the hamster cells. The release was non-cytotoxic and was in each case blocked by the corresponding soluble antigen. The rat and hamster cells responded to concanavalin A and the lectin from lentil. Phosphatidylserine (PS) potentiated the release only from the rat cells. In the absence of the lipid, the hamster cells were more reactive. The lectin from wheat germ, in the presence of PS, evoked histamine secretion only from the rat cells. Both populations were refractory to the lectin from soybean and to protein A. Rat peritoneal cells were more responsive to the basic secretagogues compound 48/80 and peptide 401 (the MCD-peptide from bee venom). These differences were less marked in the case of polylysine and polyarginine. The two cell populations responded to the calcium ionophores A23187, ionomycin and chlortetracycline. The hamster cells were significantly more sensitive to the former two liberators but markedly less reactive to chlortetracycline. Adenosine 5'-triphosphate (ATP) and dextran were potent histamine liberators from the rat cells but were totally ineffective against the hamster. Acetylcholine and carbamylcholine had no effect on either cell type. These results are discussed in terms of the functional heterogeneity of mast cells from different sources.     

Effects of adenosine-5'-triphosphate (ATP) on rat mast cells: influence on anaphylactic and compound 48/80-induced histamine release.

Anaphylactic histamine release from mast cells isolated from actively sensitized rats was inhibited by pre-incubation with micromolar concentrations of ATP. The inhibition was reversible under various experimental conditions and was counteracted by the presence of calcium in the incubation medium. Histamine release induced by compound 48/80 was similarly affected. Mast cells exposed to antigen under conditions when histamine release was inhibited by ATP became desensitized. The results indicate that ATP inhibits the release mechanism at a step which occurs after the binding of antigen to IgE.     

Inhibition of allergic and non-allergic histamine secretion from rat peritoneal mast cells by calcium antagonists.

Bepridil, TMB-8 (8-(diethylamino)octyl 3,4,5-trimethoxybenzoate hydrochloride), diltiazem, verapamil and nifedipine exerted concentration-dependent inhibition of antigen and calcium ionophore A23187-induced histamine release from rat peritoneal mast cells. The inhibitory effects of verapamil and bepridil against calcium ionophore A23187-induced histamine secretion were antagonized by increased Ca2+ concentrations in the extracellular medium. These observations suggest that both agents act by interfering with the influx of Ca2+ into the mast cells. The inhibitory activities of five different Ca2+ channel blockers on allergic and non-allergic histamine secretion from rat peritoneal mast cells varied considerably depending upon the nature of the secretagogue as well as concentration and type of Ca2+-antagonist examined.     

Parallel secretion of endogenous 5-hydroxytryptamine and histamine from mast cells stimulated by vasoactive peptides and compound 48/80.

The peptides, neurotensin, substance P, somatostatin, and bombesin, several analogues and fragments of neurotensin and compound 48/80, all caused the secretion of both endogenous 5-hydroxytryptamine (5-HT) and histamine. There was no differential effect of any of the secretagogues tested on the secretion of 5-HT and histamine. Amitriptyline prevented the secretion of histamine in response to stimulation by neurotensin, substance P, somatostatin or compound 48/80 but was without effect on the secretion of endogenous 5-HT.     

Characterization of histamine secretion induced by anthracyclines in rat peritoneal mast cells

The histamine-releasing activity of three anthracyclines, adriamycin, daunomycin and epirubicin, has been tested on rat peritoneal mast cells. The three drugs induced a marked and dose-dependent histamine secretion, in a noncytotoxic manner. The release was not sustained by extracellular calcium but was largely dependent on intracellular stores of this cation. This function was blocked by extremes of temperature (0 and 45 degrees), was very rapid and virtually complete within 10 sec. Treatment of mast cells with theophylline or disodium cromoglycate significantly reduced the secretory response to anthracyclines. On the basis of these results it is clear that the stimulant effect of anthracyclines is a true exocytotic response and thus is very similar to that of the classic mast cell secretagogue, compound 48/80.