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.     

Histamine release from the isolated guinea-pig heart by compound 48/80

Histamine release was observed in isolated guinea-pig heart perfused by the constant flow method, after bolus injection of 50-200 micrograms of compound 48/80. Practically all the histamine is released within the first 3 min after 48/80. This effect is inhibited by the addition of sodium cyanide (300 microM) to a glucose-free perfusion fluid and also by the removal of calcium of the medium in presence or absence of EDTA (100 microM). This dependence on metabolism and calcium is highly suggestive of a non-cytotoxic action of 48/80 on the mast cells of guinea-pig heart.     

Broncho-Vaxom inhibits histamine release from rat mast cells induced by compound 48/80 and ionophore A23187

Broncho-Vaxom (BV) inhibited in dose-dependent manner the release of histamine from and degranulation of isolated rat peritoneal mast cells stimulated with compound 48/80 and the ionophore A23187. Inhibition persisted after removal of BV from the incubation medium before stimulation, but did not occur when bovine serum albumin (BSA) was used instead of BV. Binding of BV to mast cells was observed by electron microscopy on cells that had been incubated with colloidal-gold labelled BV. There was no significant difference between the binding of BV gold and BSA gold to the mast cells. Washing before fixation removed most of the BV gold from the cells. This study establishes BV as an in vitro histamine release inhibitor.     

Comparison of histamine release induced by synthetic polycations with that by compound 48/80 from rat mast cells.

We compared the histamine release induced by polyethylenimines and polyallylamines with that induced by compound 48/80. Lidocaine inhibited the histamine release induced by polyethylenimine with a molecular weight of 600 (PEI6), but disodium cromoglycate did not. The histamine releases induced by all polyethylenimines and polyallylamines tested were inhibited by lidocaine, but not by disodium cromoglycate. Islet activating protein inhibited the histamine release induced by PEI6. Its effects on the release by other polyethylenimines and polyallylamines were less than that on PEI6. It is likely that the inhibition of G proteins by islet activating protein resulted in a decrease of the histamine release. This possibility was supported by the finding that guanyl-5'-(beta, gamma-imino) triphosphate enhanced the histamine release. An inhibitor of polyphosphoinositide phosphodiesterase, neomycin, did not affect the histamine releases induced by these polymers. The effect of PEI6 seemed to resemble that of compound 48/80. After pretreatment of mast cells with wheat germ agglutinin and with Limax flavus agglutinin, releases of histamine induced by PEI6 and compound 48/80 decreased, suggesting that the binding sites of PEI6 and compound 48/80 had sialic acid and/or N-acetyl glucosamine residues. The binding site for PEI6 seemed to especially overlap those of compound 48/80.     

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.     

Histamine release from rat mast cells induced by econazole.

1. Econazole released histamine from rat mast cells in vitro. This response was not affected by the addition of calcium or by prior treatment of mast cells with EDTA or cromoglycate. 2. Rat mast cells treated with econazole were stained by the vital dye trypan blue. 3. The intradermal injection of econazole increased vascular permeability. This response was antagonized by chlorpheniramine and cyproheptadine. 4. Our results demonstrate that econazole releases histamine by the "nonselective" mechanism. It is suggested that econazole inflammatory effects may be due to histamine release from mast cells.     

维生素C对氟化钠和化合物48-80诱导大鼠肥大细胞释放组胺的影响

氟化钠(NaF)和化合物48-80均可诱发大鼠胸腔，腹腔肥大细胞释放组胺，前者依赖细胞外钙参与，后者与细胞外钙关系不大，二者的最适诱导浓度分别为10 mmol·L^-1和0.2 mg·L^-1. 维生素C可促进NaF诱导的组胺释放，但对化合物48-80所诱导的组胺释放无明显影响. 将肥大细胞置于37 ℃，2 h，NaF或化合物48-80诱导的组胺释放率均下降.预先加入维生素C 1 mmol·L^-1，此现象显著减弱.由此提示：NaF激发肥大细胞，增敏其对Ca²⁺分泌作用不是由自由基引发的，另一方面也不排除37 ℃长时间温育细胞产生自由基可能与降低细胞对NaF-Ca²⁺系统和化合物48-80的敏感性有关.     

维生素C对氟化钠和化合物48-80诱导大鼠肥大细胞释放组胺的影响

氟化钠（ＮａＦ）和化合物４８－８０均可诱发大鼠胸腔，腹腔肥大细胞释放组胺，前者依赖细胞外钙参与，后者与细胞外钙关系不大，二者的最适诱导浓度分别为１０ｍｍｏｌＬ－１和０．２ｍｇＬ－１．维生素Ｃ可促进ＮａＦ诱导的组胺释放，但对化合物４８－８０所诱导的组胺释放无明显影响．将肥大细胞置于３７℃，２ｈ，ＮａＦ或化合物４８－８０诱导的组胺释放率均下降．预先加入维生素Ｃ１ｍｍｏｌＬ－１，此现象显著减弱．由此提示：ＮａＦ激发肥大细胞，增敏其对Ｃａ２＋分泌作用不是由自由基引发的，另一方面也不排除３７℃长时间温育细胞产生自由基可能与降低细胞对ＮａＦ－Ｃａ２＋系统和化合物４８－８０的敏感性有关．     

The utilization of adenosine triphosphate in rat mast cells during histamine release induced by anaphylactic reaction and compound 48/80

Summary The ATP content of rat peritoneal mast cells has been studied in relation to histamine release induced by compound 48/80 and antigen-antibody (anaphylactic) reaction in vitro. When the ATP content of actively sensitized mast cells was reduced to different levels by oligomycin, a good correlation was obtained between the ATP levels and the amounts of histamine released by the anaphylactic reaction. A similar linear relation has previously been demonstrated between the ATP levels of mast cells and histamine release induced by compound 48/80. The ATP content of mast cells was also studied at different intervals after the exposure of the cells to antigen or compound 48/80. No significant change in the ATP content was observed in untreated mast cells during the short period when histamine release occurs. If, however, the mast cells were preincubated with oligomycin or 2-deoxyglucose to reduce the rate of ATP synthesis while a large part of the histamine release remained unaffected—a decrease in the ATP content could be demonstrated in close time relation to both anaphylactic and compound 48/80-induced histamine release. The observations indicate an increased utilization of ATP in mast cells during the release 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.     

Changes in membrane potential induced by compound 48/80 in the peritoneal mast cells of rats

The changes in membrane potential induced by compound 48/80 were studied using rat peritoneal mast cells. The mean resting membrane potential of rat mast cells was -12.3 +/- 0.7 mM. When compound 48/80 was added to the mast cells, the cells were degranulated approximately 120 sec after the addition of the drug, after which immediate depolarization occurred. Degranulation of mast cells was not observed, even under the depolarization or hyperpolarization conditions caused by the replacement of a high K+ medium or the removal of K+ from the medium, respectively. Under both conditions, when compound 48/80 was added to the mast cells, degranulation was observed. Abrupt and marked depolarization was induced 30-60 sec after compound 48/80 was added. In addition, repolarization followed by gradual depolarization was observed without degranulation in mast cells treated with cytochalasin D after the addition of compound 48/80. These results suggest that the mast cells were depolarized by compound 48/80 independently of degranulation. It is also feasible that the gradual depolarization and repolarization induced by compound 48/80 in mast cells pretreated with cytochalasin D participated in the extracellular Na+ and Na+/K(+)-pump, respectively.     

Mechanisms of histamine release by compound 48/80

1. Rat and guinea-pig lung tissues were incubated for 20 min at 37 degrees C in Krebs-Ringer phosphate buffer at pH 7.4, or in Tyrode-Tris buffer at pH 8.2, and the release of histamine produced by adding different concentrations of compound 48/80 to the incubation medium was determined.2. At pH 7.4, increasing concentrations of 48/80 increased the release of histamine from the rat lung, with a tendency towards a maximum. No release of histamine from guinea-pig lung was observed at this pH. At pH 8.2, histamine release occurred both from rat and guinea-pig lung, and was proportional to the logarithm of the concentration of compound 48/80.3. Histamine release from rat lung by 20 mug/ml. of 48/80 decreased when the pH was raised from 7.4 to 8.2; but the release caused by 1 mg/ml. of 48/80 increased both in rat and guinea-pig lung as the pH was raised.4. 2-4-Dinitrophenol (DNP) inhibited the release of histamine from rat lung by a concentration of 20 mug/ml. of 48/80; the inhibition was prevented by glucose. DNP did not affect histamine release from rat or guinea-pig lung by a concentration of 1 mg/ml. of 48/80 and enhanced the release when the pH was raised from 7.4 to 8.2.5. 1 mg/ml. of 48/80 did not inhibit the enhanced oxygen consumption produced by DNP in the isolated rat diaphragm.6. Iodoacetic acid (IAA) or a Ca/Mg-free medium inhibited the release of histamine by 20 mug/ml. of 48/80 from rat lung but not the release produced by 1 mg/ml. in either rat or guinea-pig lung.7. The degranulation of rat mesentery mast cells caused by 20 mug/ml. of compound 48/80 was inhibited by DNP. The degranulation evoked by 1 mg/ml. of 48/80 was also sensitive to this inhibitor; in this instance, however, the metachromatic staining reaction of the mesentery mast cells was greatly diminished.8. It is concluded that two processes of histamine release by compound 48/80 occur in rat lung. One, dependent on cell metabolism, involves, mast cell granule secretion. The other, independent of cell metabolism, seems to consist of a simple exchange reaction between histamine and compound 48/80, and this is the only one occurring in guinea-pig lung.     

Inhibition of compound 48/80-mediated histamine release from isolated rat mast cells by oosponol-related compounds (4-acyl-isocoumarins).

Oosponol (4-hydroxymethylketone-8-hydroxyisocoumarin) is a metabolic product isolated from Oospora astringens which originated from house dust in a room of an asthmatic patient. The compound and the structurally related isocoumarins were studied to determine the inhibition of histamine release induced by compound 48/80 from isolated rat peritoneal mast cells. The released histamine was assayed by fluorometry. The compounds tested were not observed to release histamine. Some of 4-acyl-isocoumarins inhibited the histamine release at doses less than 10 micrometers, whereas the 3-acyl- and the 4-alkyl-compounds were not effective at doses over 100 microns. The pretreatment of mast cell with the compound for 15 min before the application of compound 48/80 was more effective than the simultaneous administration. The mode of inhibitory action of KIT-302, 4-(4'-carboxy-benzoyl)-isocoumarin, was non-competitive antagonism to compound 48/80 on the 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.     

Tea catechins have dual effect on mast cell degranulation induced by compound 48/80

Green tea catechins are emerging as one of the most efficient and safest ingredient in health promoting food. We investigated catechin's effects on intracellular ROS generation in mast cell activation and degranulation. Compound 48/80, receptor mimetic basic secretagogues for mast cell, induced ROS generation dose-dependently with bell-shaped degranulation pattern in canine cutaneous mastocytoma cells (CM-MC). When intracellular ROS level was relatively low, catechins decreased both ROS and the degranulation. However, when intracellular ROS level was remarkably high, catechins decreased ROS level but increased the degranulation paradoxically. Gallocatechins showed the stronger effects than non-gallated catechins. Exogenous H(2)O(2) also shows dual effect on degranulation dose-dependently. EGCG shows the dual effect on the tyrosine and threonine phosphorylation depending on the concentration of compound 48/80. Particularly, 60 kDa protein tyrosine-phosphorylated by EGCG with 3 microg/ml of compound 48/80 might be a negative regulator for the degranulation. Taken together, there is an optimal level of ROS for the degranulation, and the catechins have a dual function by controlling ROS level.