Inhibitory Action of Exogenous Adenosine-5′-triphosphate on Glycolysis in Isolated Rat Mast Cells: Significance for Histamine Release

Abstract: Histamine release and lactate content were concomitantly determined in samples of isolated rat mast cells. Histamine release induced by exogenous ATP or compound 48/80 was inhibited by antimycin A (0.2 μM). Glucose (0.60 mM) restored the release induced by compound 48/80 but not that induced by ATP. ATP but not compound 48/80 inhibited the accumulation of lactate in suspensions of mast cells containing glucose (0.60 mM). ATP induced inhibition of lactate accumulation and release of histamine within the same concentration range. However, the time courses for the two processes were different. Antimycin A (0.2 μM) enhanced the accumulation of lactate, an effect which was counteracted by ATP. 0.05 mM ATP or more reduced the lactate accumulation to the same values as those found in the absence of antimycin A. The inhibitory action of ATP on glycolysis may explain the observed inability of glycolytic substrates to restore the ATP-induced histamine release blocked by inhibitors of oxidative metabolism.     

alpha-Fluoromethylhistidine. Kinetics of uptake and inhibition of histamine synthesis in basophil (2H3) cell cultures

Labeled histidine was taken up into rat leukemic basophil 2H3 cells by a system with high affinity for histidine and then decarboxylated to form histamine. Uptake was partially inhibited and decarboxylation was completely blocked by alpha-fluoromethylhistidine (alpha-FMH) at concentrations of 10-100 microM. alpha-FMH appeared to be co-transported by a histidine uptake system but the affinity of the system for alpha-FMH was lower than that for histidine (Km 130 and 24 microM, respectively). The drug rapidly penetrated into and became highly localized within the cells. By 60 min the apparent IC50 for inhibition of histamine synthesis in intact cell suspensions was 0.2 microM compared to an IC50 of 1-2 microM alpha-FMH for inhibition of soluble histidine decarboxylase preparations. Turnover of histidine decarboxylase activity in 2H3 cells was rapid (t1/2, 37 min), and biphasic effects were noted after 24-h exposure of 2H3 cells to drug. At low concentrations (greater than 0.1 microM), decarboxylase activity was increased (up to 134 +/- 9% of control values). Higher concentrations of the drug (0.1-10 microM) were inhibitory, and inhibition was related to drug concentration. No detectable decarboxylase activity was observed with 10 microM alpha-FMH after 4 days. Histamine levels increased (up to 232 +/- 2% of control values) or decreased in parallel with decarboxylase activity. Even in cultures devoid of histamine or decarboxylase activity (with 10 microM alpha-FMH) cell division and growth were not affected. Thus the drug appeared to inhibit specifically histamine synthesis without impairing essential cellular metabolic processes. However, kinetics of drug uptake and perturbation of enzyme turnover are additional factors to be considered in the action of alpha-FMH in intact cell systems.     

Cyclic AMP independent inhibition by papaverine of histamine release induced by compound 48/80.

Compound 48/80-induced histamine release from isolated rat peritoneal mast cells was inhibited in a dose-dependent manner by papaverine (ic₅₀ approx 20 μM). This effect of papaverine was not influenced by PGE₁ (14–140 μM), even though PGE₁ markedly increased must cell cAMP levels. Papaverine (0.5 mM) completely inhibited histamine release without causing any change in cAMP levels. Theophylline (0.1 and 0.5 mM) potentiated histamine release induced by submaximal concentrations of compound 48/80, while cAMP levels were increased. IBM X was as potent as papaverine in causing inhibition of mast cell phosphodiesterase. IBM X (0.14–0.7 mM) had no effect on histamine release but caused a 6–20 fold increase in mast cell cyclic AMP. Papaverine inhibition of histamine release was gradual at the onset and was parallelled by a depletion of mast cell ATP content. The inhibition of 48/80-induced histamine release and depletion of mast cell ATP levels was reversed by glucose. It is concluded that papaverine induced inhibition of 48/80-induced histamine release is independent of cAMP, is unrelated to phosphodiesterase inhibition but is dependent upon inhibition of energy production.     

A comparative study of histamine and K+ effects on (Ca(2+)-Mg2+)-ATPase activity in synaptosomes.

Histamine (10(-4) M) and 60 mM K+, but not 60 mM Na+ or 60 mM choline+, increased the maximal synaptosomal (Ca(2+)-Mg2+)-ATPase activity by 15 and 36% respectively and decreased the extrasynaptosomal Ca2+ concentration necessary to reach it. Histamine and K+ enhanced the synaptosomal (Ca(2+)-Mg2+)-ATPase activity in a concentration-dependent manner. In synaptic plasma membranes histamine (10(-4) M) and 60 mM choline+ were not able to alter the enzymatic activity, however 60 mM K+ and 60 mM Na+ elevated (Ca(2+)-Mg2+)-ATPase activity by 20 and 15%, respectively, without altering the affinity for Ca2+. Histamine effects in synaptosomes were mediated by H2 receptor stimulation. 3-Isobutyl-1-methyl-xanthine (10(-4) M) potentiated (15%) the maximal histamine effect. The slow Ca2+ channel antagonists verapamil and diltiazem, both at 10(-6) M, completely inhibited K+ effects in synaptosomes, however histamine effects were only blocked by verapamil. The data suggest that K+ and histamine effects on synaptosomal (Ca(2+)-Mg2+)-ATPase activity are mediated by increases of intrasynaptosomal Ca2+ levels. Moreover, histamine effects on synaptosomal enzyme activity were mediated by cAMP.     

The actions of retinal and retinoic acid on histamine release from rat peritoneal mast cells

Histamine release from rat peritoneal mast cells induced by anti-IgE was potentiated by the retinoids: retinoic acid 2-10 microM and retinal 1-5 microM. Retinal also produced a concentration-dependent increase in anti-IgE-stimulated 45Ca uptake by these mast cells. A similar potentiating action of both retinoids was observed on histamine release induced by 12-O-tetradecanoylphorbol-13-acetate (TPA). For both anti-IgE- and TPA-induced histamine release, the potentiating effect of the two retinoids was only observed in the presence of extracellular calcium. In contrast, histamine release induced by compound 48/80 was inhibited by retinal 1-5 microM and by retinoic acid 10-50 microM and the inhibition was the same in the presence as in the absence of extracellular calcium 1 mM. Histamine release induced by calcium and the calcium ionophore A 23187 was inhibited by retinoid acid 2-10 microM and by retinal 10 microM. Inhibitions of compounds 48/80-induced histamine release by cromoglycate and by retinal were additive. It is concluded that while the actions of retinoids on rat peritoneal mast cells are consistent with the inhibition of protein kinase C, another action of these compounds, unrelated to this enzyme, may explain the data.     

Beta-adrenoceptor stimulation inhibits histamine-stimulated inositol phospholipid hydrolysis in bovine tracheal smooth muscle.

1. Histamine and carbachol produced concentration-related increases in the accumulation of 3H-inositol phosphates in slices of bovine tracheal smooth muscle. 2. Noradrenaline alone produced a small stimulation of 3H-inositol phosphate accumulation which was inhibited by the alpha-adrenoceptor antagonist phentolamine. In contrast, when noradrenaline (0.1 mM) was added simultaneously with histamine it significantly reduced the inositol phosphate response to high (greater than or equal to 0.1 mM) concentrations of histamine. However, noradrenaline had no inhibitory effect on the carbachol-induced inositol phosphate response. 3. The non-selective beta-agonist isoprenaline (IC50 = 0.08 microM) and the beta 2-selective agonist salbutamol (IC50 = 0.29 microM) both produced a dose-related inhibition of the inositol phosphate response to 0.1 mM histamine. The inhibitory effect of salbutamol was antagonized by propranolol (KA = 2.4 x 10(9) M-1) and the beta 2-selective adrenoceptor antagonist ICI 118551 (KA = 1.7 x 10(9) M-1). 4. The accumulation of 3H-inositol phosphates induced by histamine increased steadily over a 40 min period after an initial lag period of 3-4 min. Following the simultaneous addition of histamine and salbutamol there was a further delay of 3-4 min before the appearance of the inhibitory effect of salbutamol. 5. The effect of histamine on inositol phosphate accumulation was accompanied by a stimulation of [3H]-inositol incorporation into membrane phospholipids which was reduced by the presence of salbutamol.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evidence for the role of cAMP-dependent protein kinase in the down-regulation of hypothalamic HD: reversal of cAMP-(ATP) induced inhibition of HD activity by the 'Walsh' inhibitor of cAMP-dependent protein kinase and by cyclic GMP

Under the total blockade of PDE1 and the presence of endogeneous ATP and MgCl2, the inhibitory effect of cAMP on HD activity could be demonstrated as low as 8.7 X 10(-8) M concentration in a 20,000 g supernatant of a sustained homogenate of rat hypothalamus. A total reverse of this action and also a partial release of the cAMP-induced inhibition of HD, occurred at higher concentrations of cAMP, and ATP could be achieved by an endogeneous inhibitor of cAMP-dependent protein kinase or by cyclic GMP. The reversal of cAMP action by PKI seems to serve a strong evidence for the role of cAMP-dependent protein kinase (EC 2.7.37: ATP-protein phosphotransferase) in this action and emphasized the involvement of a direct or an indirect phosphorylation in the regulation of HD activity. The stimulatory effect of cyclic GMP on cAMP-induced inhibition of HD or its 'direct' effect on histamine formation is asserted, probably through the activation of PDE, or through independent stimulatory machinery, coupled to the cyclic GMP system.     

Effects of barbiturates on energy metabolism by cultured astrocytes and neurons in the presence of normal and elevated concentrations of potassium

Rates of consumption of oxygen and of the formation of CO2 from [U-14C]glucose were studied in primary cultures of either astrocytes or neurons of the cerebral cortex. An increase of the extracellular concentration of potassium from 5 to 55 mM caused an increase in uptake of oxygen and in the production of CO2 in the astrocytes but not in the neurons. Pentobarbital (0.25-1.0 mM) or phenobarbital (1 mM) abolished the stimulation of oxygen uptake and/or the production of CO2 produced by potassium in the astrocytes with less (CO2 production) or no (oxygen uptake) effect at a normal concentration of potassium. In the neurons, pentobarbital (0.1-1.0 mM) caused, in contrast, a moderate inhibition of the production of CO2 and uptake of oxygen which was at least as pronounced at the small concentration of potassium. These results suggest that the pronounced inhibition of the stimulation of uptake of oxygen induced by potassium in brain slices is exerted on astrocytes, whereas the more modest decrease in uptake of oxygen at a small concentration of potassium is a neuronal phenomenon.     

Effect of cyclic AMP, db-cyclic AMP and phosphodiesterase inhibitors on histamine inhibition of the contractile response of the mouse vas deferens

Histamine inhibited the contractile response of the mouse vas deferens to various frequencies of stimulation, and the inhibition was inversely related to the frequency of stimulation. This effect of histamine was mimicked by cyclic AMP, db-cyclic AMP and various phosphodiesterase inhibitors (IBMX, aminophylline and theophylline). Histamine-produced inhibition, but not that produced by the other compounds, was blocked by cimetidine. The low concentrations (10-100 microM) of various phosphodiesterase inhibitors caused inhibition but failed to potentiate the inhibitory response to histamine. The basal cyclic AMP levels of the tissues were unaffected at these concentrations of aminophylline. At higher concentrations (1 and 5 mM), however, aminophylline significantly elevated the basal cyclic AMP levels of the tissues and markedly inhibited the contractile response to various frequencies of stimulation but still failed to enhance or potentiate the inhibitory response to histamine. In fact, the inhibitory response to histamine at these concentrations of aminophylline was reduced. Based on these and earlier [3] findings, it is concluded that, although histamine increases the accumulation of cyclic AMP in the mouse vas deferens and although its inhibitory effect on the preparation can be mimicked by both the cyclic nucleotides and phosphodiesterase inhibitors, the involvement of cyclic AMP in the mediation of its inhibitory response is still unresolved.     

Influence of aminoglycoside antibiotics, streptomycin and kanamycin on histamine secretion in mast cells.

Effects of kanamycin and streptomycin on histamine release from rat mast cells were examined in response of the cells to concanavalin A(Con A) plus phosphatidylserine (PS), phytohemagglutinin (PHA) plus PS or a mixture of low-molecular-weight polymers of P-methoxy-N-methylphenethylamine (compound 48/80). In the response to each of the above stimuli, kanamycin (20 mM) or streptomycin (20 mM) caused a decrease in the histamine release elicited in the presence of extracellular Ca2+ (1 mM), although streptomycin showed the much higher inhibitory potency than kanamycin. Similarly, streptomycin was much more effective in suppressing compound 48/80-triggered histamine release in the absence of external Ca2+. Histamine release in the absence of external Ca2+ in the response to the lectin plus PS diminished with increasing concentration of kanamycin, and in this respect streptomycin was much less effective. In the response to the lectin plus PS, external Ca2+ possessed potency to antagonize kanamycin (10 mM)- or streptomycin (10 mM)-caused inhibition of the histamine release, although more markedly the kanamycin-caused one. Streptomycin and kanamycin inhibit histamine release from mast cells challenged with IgE-directed secretagogue or compound 48/80, and the responsible mechanisms seem to implicate the Ca(2+)-antagonistic action on the stimulus-provoked influx of Ca2+ and impairment of the cellular events linked to exocytosis.     

The effects of some possible inhibitors of ectonucleotidases on the breakdown and pharmacological effects of ATP in the guinea-pig urinary bladder

1. The effects of some possible inhibitors of ectonucleotidases on the breakdown of extracellular ATP by strips of guinea-pig urinary bladder were investigated. 2. Suramin and ethacrynic acid (10 mM) both inhibited ATP breakdown significantly, and difluorodinitrobenzene (10 mM) inhibited it slightly whereas N-ethylmaleimide, adenosine 5'-(gamma-thiotriphosphate) (ATP-gamma-S) and reactive blue-2 (10 mM) were without effect. 3. The inhibitory effects of suramin on ATP breakdown were non-competitive. 4. Ethacrynic acid (1 mM) irreversibly inhibited contractions of the guinea-pig bladder induced by ATP, substance P, histamine, non-adrenergic, non-cholinergic nerve stimulation or KCl, whereas suramin (100 microM) had no inhibitory effect. 5. The results suggest that suramin might provide a starting point for the design of selective inhibitors of ectonucleotidases.     

Studies on the mechanisms of the inhibitory effect of N-5' on histamine release from rat peritoneal exudate cells

To investigate the mechanisms for the inhibition of IgE-mediated histamine release from rat peritoneal exudate cells (PEC) by N-5', we studied the relation between the inhibitory effect of N-5' on histamine release and the intracellular levels of adenine nucleotides such as ATP and cAMP. Evident histamine release was induced by the addition of specific antigen to rat PEC sensitized with IgE antiserum in vitro, and the release showed a maximum 30 sec after the antigen challenge. In the same time course as the histamine release, the intracellular levels of ATP and cAMP decreased. N-5' significantly inhibited the histamine release and a decrease in ATP level as a result of the antigen-antibody reaction. A decrease in cAMP level showed a tendency to be suppressed by N-5'. Antigen-induced 14CO2 production for 6-14C-glucose in the sensitized PEC was 3 times that seen in the case without antigen. N-5' dramatically suppressed the acceleration in the production of 14CO2. Differing from the action of papaverine, the inhibitory effect of N-5' on the IgE-mediated histamine release from rat PEC was identical both in the presence or in the absence of glucose. N-5' scarcely affected the ATP level in the non-sensitized PEC in the glucose-free medium. On the other hand, N-5' inhibited the activity of Na+, K+-ATPase, one of the ATP-consuming enzymes, in a dose-dependent fashion. From these results, it is presumed that the suppression of ATP-utilization through the inhibition of Na+, K+-ATPase activity is involved in the inhibition of histamine release by N-5'. The relation between the inhibitory effect of N-5' on histamine release and both nucleotides was also discussed.     

Amine transport in isolated rat mast cells treated with betaadrenoceptor blocking drugs

Histamine and serotonin uptake in isolated rat mast cells is decreased in the presence of betaadrenoceptor blocking (BAB) drugs. Such inhibition is dose-dependent and is evidently higher for the inhibition of serotonin uptake. The most potent drugs were the highly lipophilic compounds K? 1124 and propranolol. No difference was found among the various BAB drugs in their ability to decrease histamine uptake. It is evident from the ratio between histamine and serotonin liberation on one side, to the uptake of both amines in mast cells on the other side, that with the exception of K? 1124, all investigated BAB drugs possesses higher inhibition of extracellular amine uptake in comparison with histamine and serotonin liberation. Such an effect might be a result of a primary interaction of BAB drugs with mast cells at the plasma membrane.     

Histamine inhibition of mixed function oxidase activity in rat and human liver microsomes and in the isolated perfused rat liver

The imidazole ring is a common structural feature of some xenobiotics that inhibit cytochrome P-450-catalysed reactions. Histamine is a 4-substituted imidazole and a preliminary study has shown it to be an inhibitor of rat liver microsomal drug oxidation. This work has now been extended. Histamine appears to be a competitive inhibitor of the alpha-hydroxylation (HM) (Ki = 164 microM; IC50 at 20 microM = 308 microM) and O-demethylation (ODM) (Ki = 243 microns; IC50 at 20 microM = 400 microM) of metoprolol in rat liver microsomes. Of the metabolites of histamine only N-acetylhistamine showed comparable inhibitory potency to that of the parent compound. Histamine impaired the disappearance of lignocaine when incubated with rat liver microsomes. This was accompanied by a corresponding inhibition of 3-hydroxy-lignocaine appearance. Histamine produced a type II spectral interaction with rat liver microsomes (lambda max = 432 nm, lambda min = 408 nm; Ks = 0.11 mM). When histamine was incubated alone with rat liver microsomes no loss of substrate was observed. The oxidation of metoprolol by human liver microsomes was impaired by histamine (IC50 values for ODM appearance at 25 microM: liver HL1 greater than 10, HL3 = 3.8 and HL4 = 3.7 mM). In comparison, cimetidine had an IC50 value of 1.5 mM using microsomes from liver HL3. Addition of histamine impaired the elimination of metoprolol by the isolated perfused rat liver in a dose-dependent manner (P less than 0.001, one-way analysis of variance). These data demonstrate that histamine can enter hepatocytes, interact with cytochrome P-450 and inhibit some drug oxidation reactions. The physiological relevance of inhibition of drug metabolism by histamine remains to be determined.     

Kinetic studies on the mechanism by which histamine H1 receptors potentiate cyclic AMP accumulation in guinea pig cerebral cortical slices

Histamine, acting via H1 receptors, augments adenosine-induced cAMP accumulation in slices of guinea pig cerebral cortex by an indirect mechanism that appears to involve an intracellular messenger(s). To better characterize this process, the time course of this augmentation was examined in slices prelabeled with [3H] adenine. When histamine (1 mM) was added after the cAMP level had reached steady state with adenosine (0.1 mM), the cAMP level rose to a new steady level within 10 min (t 1/2, 2-3 min). There was no measurable delay in this response, indicating rapid activation of the augmentation after receptor occupation. Studies using the H1 receptor antagonist mepyramine indicated that the continued presence of the histamine stimulus was required to maintain the augmentation. Addition of mepyramine (10 microM) between 1 and 14 min after histamine caused cAMP levels to fall to a level similar to that obtained previously with adenosine alone, but with a delay of 2-3 min. This gives an upper estimate of the lifetime of any intracellular messenger involved in the augmentation process. To determine whether histamine acts by stimulating synthesis of cAMP or by inhibiting its breakdown, the fall in tissue cAMP content was studied after rapid removal of the adenosine stimulus by addition of adenosine deaminase. The initial fall was significantly faster in slices incubated with 0.1 mM adenosine plus 1 mM histamine than in slices with 0.1 mM adenosine alone, indicating increased synthesis and breakdown of cAMP in the presence of histamine. However, the higher breakdown rate probably reflects stimulation of the degradation process by the higher initial level of cAMP with histamine because, at equivalent levels, cAMP content fell at similar rates in both conditions. This was confirmed in other experiments in which similar steady state cAMP levels were achieved with and without histamine by appropriate choice of adenosine concentrations. It is therefore concluded that the direct effect of histamine is primarily to potentiate cAMP synthesis.     

Evidence for rapid histamine turnover and loss of histamine from immature rat mast cells

Histamine synthetic activity which is high in young mast cells decreases as the cells mature [Beaven et al., J. Pharmac. exp. Ther. 224, 620 (1983)]. In this study we show that a substantial proportion of newly formed histamine in young mast cells leaked to the extracellular environment. The cells acquired the full ability to sequester newly formed histamine once the numbers of intracellular granules and the supply of sulfated mucopolysaccharide material within them had increased. Rat peritoneal mast cells were separated into successive fractions of increasing size and maturity by counter current elutriation. Loss of histamine from fractions of immature cells was demonstrated by a progressive accumulation of histamine in the medium without any decrease in intracellular histamine content. The estimated turnover time of histamine was less than 10 hr. In fractions of more mature cells, the proportion of cellular histamine released into the medium was substantially lower, giving estimated turnover times of 20 hr or longer. Studies with radiolabeled histidine also indicated that little, if any, newly formed histamine was lost from fractions of mature cells. Both release of endogenous histamine and formation of radiolabeled histamine from labeled histidine were inhibited by the histidine decarboxylase inhibitor alpha-fluoromethylhistidine (10 microM). Histamine turnover times were similar in the presence or absence of external histidine, a possible indication that the supply of intracellular histidine was sufficient to maintain normal histamine synthetic activity.     

The effects of H2-receptor antagonists on anaphylaxis in the guinea-pig.

Histamine has been shown to inhibit a variety of immune responses including the antigen-induced, IgE mediated, release of histamine from sensitized human leucocytes and from sensitized monkey and dog mast cells. The inhibitory action of histamine appears to be mediated by action at a histamine H2-receptor. In in vitro experiments the H2-receptor antagonist metiamide has been shown to block this histamine effect and it has been suggested that H2-receptor antagonists could intensify immediate hypersensitivity reactions in vivo. The effects of the H2-receptor antagonist metiamide and cimetidine have been studied in in vitro and in vivo models of anaphylaxis in the guinea-pig. The amount of extracellular histamine found after antigen challenge is greater when an H2-receptor antagonist is present during the incubation of mast cells with antigen. Bronchoconstriction induced by antigen in sensitized guinea-pig is exacerbated only by high doses of cimetidine. Possible explanations for the mechanism of action involved are discussed.     

Histamine stimulates glycogen breakdown and increases 45Ca2+ permeability in rat astrocytes in primary culture

In astrocyte-enriched cultures from rat brain hemispheres prelabeled with [3H]glucose, histamine stimulates [3H]glycogen breakdown in a concentration-dependent manner, with an EC50 of 0.6 microM. This effect can be induced by activation of both H1 and H2 receptors independently. Thus, neither 1 microM promethazine, an H1 antagonist, or 100 microM metiamide, an H2 antagonist, inhibited the glycogenolytic response to histamine unless they were present together. In addition, the maximal effect of histamine (55% decrease in [3H]glycogen) was also elicited by 300 microM 2-thiazolylethylamine, an H1 agonist, and by 1 mM dimaprit, an H2 agonist. These agonist effects were inhibited by promethazine and metiamide, respectively, and were not additive, indicating that the same glycogen pool was affected. Histamine was more potent in eliciting glycogenolysis through H1 (EC50 of 0.4 microM in the presence of 100 microM metiamide) than through H2 (EC50 of 3.3 microM in the presence of 1 microM promethazine) receptors, as also shown previously for the H1-mediated phosphoinositide hydrolysis compared with the H2-mediated cAMP formation in the same cells. Both dibutyryl cyclic AMP and the Ca2+ ionophore A23187 could independently mimic the glycogenolytic effect of histamine, whereas the absence of extracellular Ca2+ abolished the H1 component of the response. Histamine also stimulated rapid transmembrane 45Ca2+ influx (maximum, 48% of basal at 15 sec) and efflux (maximum, 25% of basal at 1 min) in astrocytes by activation of H1 receptors. This histamine-increased 45Ca2+ entry was abolished by the nonspecific Ca2+ channel blocker lanthanum but not by the voltage-operated Ca2+ channel inhibitor nifedipine. The enhanced 45Ca2+ release was more a consequence of the histamine-increased Ca2+ permeability than intracellular Ca2+ mobilization, because it was largely diminished when Ca2+ entry was prevented and was little affected by pretreatment of the cells with 12-O-tetradecanoyl-phorbol-13-acetate. Thus, the histamine-induced glycogen breakdown in astrocytes may involve increases in cAMP formation and in intracellular Ca2+ levels, this latter resulting mainly from H1-mediated extracellular Ca2+ uptake.     

Calcium uptake in mast cells, energy metabolism and histamine secretion

The inhibition of energy metabolism of mast cells causes an inhibition of histamine secretion. As the secretion is generally initiated by the influx of calcium into the cell, we have made correlative studies of the effect of blocking the energy metabolism on calcium uptake and histamine secretion. When the influx of calcium is increased by exposing the cells to low concentrations of saponin or ionophore A23187, histamine release occurs, having the character of a secretory response. Brief incubation of the cells with antimycin A, 10(-9) M-10(-7) M, prior to exposure to saponin or the calcium ionophore gave similar dose-response curves for the inhibitory effect of antimycin A on calcium uptake and histamine release. The inhibition of calcium uptake in untreated mast cells by antimycin A, 10(-9) M-10(-7) M, showed good correlation to the inhibition of anaphylactic histamine release and the release induced by compound 48/80. The antigen-induced histamine release is dependent on extracellular calcium and an inhibition of its uptake by antimycin A could by itself inhibit the release. Compound 48/80 on the other hand induces histamine release both in the presence and absence of calcium, and both are similarly inhibited by 10(-9) M-10(-7) M antimycin A. This indicates that antimycin A has other sites of action apart from the inhibition of the influx of extracellular calcium. The inhibitory effect of antimycin A on compound 48/80-induced histamine secretion in the absence of extracellular calcium may be due to an inhibition of energy requiring steps in the final phase of the secretory process.(ABSTRACT TRUNCATED AT 250 WORDS)     

The action of local anaesthetics on histamine release.

The effect of the local anaesthetics lidocaine, procaine and tetracaine on compound 48/80-induced histamine release from isolated rat mast cells has been investigated. They inhibited histamine release in a dose-dependent manner; at a concentration of 20 mM there was almost total inhibition of histamine release by lidocaine and about 75% inhibition by procaine. Tetracaine exerted a biphasic effect: at concentrations below 1 mM it inhibited, but at concentrations above 1 mM it potentiated histamine release. The inhibitory effect of lidocaine on compound 48/80-evoked histamine release was dependent upon the time of preincubation of mast cells with this anaesthetic and it persisted after washing the cells and resuspension in a lidocaine-free medium. An increase of calcium ions antagonized the inhibitory action of lidocaine. These results can be explained by (1) blockade of membrane receptors for calcium binding which leads to a decrease in intracellular calcium concentration and (2) increase of cellular cyclic AMP content which subsequently inhibits the releasing process.