Collagen-derived peptides release mast cell histamine

The effect of collagen degradation products by bacterial (BCDP) and synovial fluid collagenase (SCDP) on histamine release from peritoneal mast cells of rat was estimated. Some BCDP as well as SCDP released 60-80% of mast cell histamine. In BCDP fraction the most active were BCDP II (m.wt. 13 kD) and BCDP III (m.wt. 6 kD). The last contained the highest percentage of hydroxyproline. As compared with bradykinin, BCDP III was about 50 fold more active as histamine releaser.     

Anthracycline-induced histamine release from rat mast cells

Comparisons were made of the ability of doxorubicin, daunorubicin, rubidazone and aclacinomycin A to release histamine from rat peritoneal mast cells. Preliminary in vitro experiments indicated that doxorubicin (10(-6) to 2.5 X 10(-4) M), in contrast to compound 48/80 and the calcium ionophore A23187, did not produce significant release under any condition tested when purified or unpurified rat mast cells were used. In in vitro experiments, released histamine was measured in the cell-free supernatant of peritoneal fluid of rats after intraperitoneal injection of the agents. The time course of doxorubicin-induced histamine release from the peritoneum was rapid, with maximal release occurring within 4 to 6 min. Dose-response curves of the 4 agents over the range 10(-5) to 3.3 X 10(-3) M revealed that all caused histamine release, with 10(-3) M concentrations of each causing maximal release of comparable magnitude to that produced by 9.5 X 10(-6) M A23187. Treated mast cells recovered from the peritoneal cavity showed degranulation and vacuolization when examined by electron microscopy. Increased vascular permeability by the Evans-blue test was also noted with all 4 agents, and zones were of comparable size after injection of the highest concentration of each agent. The results indicate that in vivo, doxorubicin, daunorubicin, rubidazone and aclacinomycin A cause a rapid release of histamine from rat mast cells and an increase in vascular permeability in rat sin. There also appeared to be a reasonable correlation between the blueing reaction and histamine release in the peritoneal cavity in that the doses that did not cause skin blueing also failed to cause histamine release. The lack of histamine release by doxorubicin from mast cell preparations in vitro suggests that alterations to the doxorubicin molecule or the presence of other critical substances may be necessary for this activity to commence.     

Characteristics of histamine and serotonin release from rat mast cells induced by thymic peptides.

Thymopoietin peptides release histamine and serotonin from rat mast cells. The release has the characteristics of other basic secretagogues in that it occurs rapidly, does not require extracellular Ca2+ ions, and is inhibited by benzalkonium chloride (BAC). These similarities indicate that chemically different basic compounds have common mechanisms for histamine and serotonin release from rat mast cells.     

Non-differential inhibition of histamine and serotonin release from mast cells by amitriptyline

A differential amine release from mast cells induced by an inhibitory effect of the antidepressant drug amitriptyline on the release of histamine but not on that of serotonin has recently been reported. In view of the potential biological importance of a differential release of mast cell amines we have studied the effect of amitriptyline on the dynamics of the secretory process using a combination of vital berberine staining (demonstrating intracellular granules that have released amines) and measurement of histamine, serotonin (5-HT), and heparin release. The results show a non-differential inhibition of the release of histamine and 5-HT by amitriptyline. The basic pattern of the secretory process, studied in terms of granule extrusion and amine release from intracellular granules, was unaffected by the drug.     

Peptides and histamine release from rat peritoneal mast cells

Various vasoactive peptides were compared for their histamine releasing effects on rat mast cells. Neurotensin, substance P (SP), and kallidin were the most active natural peptides, followed by bradykinin; neurokinin A and B, bombesin, angiotensin and tuftsin were practically inactive. Several kinins and tachykinin-related peptides were tested in an attempt to characterize the receptors mediating histamine liberation. The order of potency of the kinins was the following: kallidin greater than [Tyr(Me)8]bradykinin = bradykinin greater than [desArg10]kallidin greater than desArg9-bradykinin, the same as that found in smooth muscle possessing receptors of the B2 type. Tachykinin-related peptides were potent stimulants and followed the order: [D-Tryp7,9,10]SP-(1-11) greater than [D-Pro2,D-Tryp7,9,10]SP-(1-11) greater than SP-(1-11) greater than SP-(1-9) greater than [D-Pro4,D-Tryp7,9,Leu11]SP-(4-11) greater than SP-(1-7) greater than SP-(4-11) greater than neurokinin A = neurokinin B, indicating that: (a) undecapeptide antagonists of SP behave as superagonists; (b) both N- and C-terminal portions of SP-(1-11) are essential for activity; and (c) receptors for the tachykinins mediating histamine release appear to be of the SP-P type.     

Ischaemic preconditioning and mast cell histamine release: microdialysis of isolated rat hearts.

The aim of this study was to investigate the feasibility of intramyocardium kinetics of histamine release by microdialysis in the isolated rat heart and ascertain if the inhibition of histamine release is implicated in the antiarrhythmic effect of preconditioning. A 30 min normothermic global ischaemia model followed by 30 min reperfusion was carried out in the control group (n= 9). In the preconditioning group (n= 8) there was a 5 min global ischaemia followed by 10 min of reperfusion. A mast cell stabilizing group received the disodium cromoglycate ( 10 micro M, n= 10). The last group received a mast cell degranulator, compound 48/80 (1micro g ml (-1), n= 10). In the control group, the histamine release during reperfusion was significantly different from the basal concentration ( 18.4 +/- 6.5 vs 1.9 +/- 0.5 nM, P< 0.05) and was associated with a maximal period of severe arrhythmias. The ischaemic preconditioning modified the histamine release kinetics with an early mast cell degranulation ( 9.7 +/- 1.5 nM) and a significant decrease in the total period of severe arrhythmias in comparison with the control group ( P< 0.05). In the disodium cromoglycate group, the histamine release during reperfusion decreased ( 3.1 +/- 0.7 nM) and was associated with a maximal period of severe arrhythmias. In the C48/80 group, the increase in the histamine released during reperfusion ( 21.2 +/- 5.0 nM) was associated with a maximal period of severe arrhythmias. These results showed firstly the feasibility of kinetic histamine release in myocardium interstitial fluid on the isolated rat heart and secondly that the inhibition of histamine release did not play a direct role in the antiarrhythmic effect of preconditioning.     

Hypotension induced by growth-hormone-releasing peptide is mediated by mast cell serotonin release in the rat.

Growth-hormone-releasing peptide (GH-RP-6) is a synthetic hexapeptide that selectively releases growth hormone (GH) when administered to a number of animals species. In the rat, maximal GH release occurs after intravenous administration of 100 micrograms/kg GH-RP-6. Intravenous administration of 5 mg/kg GH-RP-6 produced 100% lethality within 2-5 min of drug administration. Further investigative studies demonstrated that the lethal effect of GH-RP-6 was preceded by an initial hypertensive episode, followed by a rapid, profound hypotension and bradycardia. The rise and fall in blood pressure also were observed in pithed rats treated with GH-RP-6, suggesting that the central nervous system was not responsible for the changes in blood pressure. However, the GH-RP-6-induced bradycardia was not observed in pithed rats, indicating the fall in heart rate was mediated through a central reflex mechanism. No direct effects of GH-RP-6 were seen in the isolated rat aorta or canine saphenous vein. Pretreatment of conscious rats with naloxone (10 mg/kg, iv), an opiate receptor antagonist, did not prevent the hypertensive response to GH-RP-6, but the hypotension and lethality were attenuated. Pretreatment with cyproheptadine (2.5 mg/kg, iv), a dual serotonin/histamine antagonist, or ketanserin (3 mg/kg, iv), a selective serotonin antagonist, prevented the GH-RP-6-induced hypotension and lethality. Cyproheptadine unmasked a 40 mm Hg rise in mean arterial pressure which persisted for over 10 min. In addition, degranulation of mast cells with compound 48/80 inhibited the toxicity of GH-RP-6, suggesting that mast cell degranulation and the subsequent release of autocoids is responsible for the cardiovascular effects of GH-RP-6. In vitro, GH-RP-6 (10(-5) - 10(-3) M) produced a concentration-related release of histamine from rat peritoneal mast cells. However, the histamine release by GH-RP-6 (10(-4) M) was not inhibited by naloxone (10(-4) M) in isolated mast cells, suggesting either that peritoneal mast cells are not responsible or that the mast cell degranulation in vitro is not opiate mediated. In conclusion, it appears that GH-RP-6 degranulates mast cells releasing serotonin, which produces hypotension, bradycardia, and death. This degranulation of mast cells is apparently inhibited by naloxone in vivo, suggesting that opiate receptors are involved in the hypotension and lethality associated with the administration of GH-RP-6.     

Role of intracellular calcium in histamine release from rat mast cells

An aqueous extract of Panax Ginseng C.A. Meyer (G.S.) was prepared by boiling crushed G.S. roots in water. The extract obtained was adjusted to 125 mg G.S. per ml and was administered orally to mice for 5 to 6 days at the daily dose of 10, 50 and 250 mg G.S. per kg or was added to cultures of mouse spleen cells at concentrations varying between 0.25 and 8 mg G.S. per ml. The average total ginsenoside content of the G.S. roots used was determined by HPLC analysis and found to be 0.58% (w/w). Treated mice responded with enhanced antibody formation to either a primary or a secondary challenge with sheep red cells. The effects were dose-dependent. At the highest dose regimen, the primary IgM response was increased by 50% and the secondary IgG and IgM responses were increased by 50 and 100%, respectively. An even more pronounced effect was obtained with natural killer cell activity which was enhanced between 44 and 150% depending on the effector-to-target cell ratios used in the assay. In vitro, G.S. showed two main effects, an inhibition of stimulated and spontaneous lymphocyte proliferation at high, but not cytotoxic concentrations and an enhancement of interferon production particularly in non-stimulated spleen cells. The immunostimulating effects obtained in vivo are in agreement with the stimulation of interferon production observed in vitro. The inhibition of lymphocyte proliferation, however, cannot be reconciled with the immunostimulatory action of G.S. observed in vivo.     

Apomorphine-induced inhibition of histamine release in rat peritoneal mast cells.

The apomorphine-induced inhibition of histamine release in rat peritoneal mast cells was studied by means of secretagogues stimulating different pathways of mast cell activation. Apomorphine inhibited the mast cell response to all releasing agents (lysophosphatidylserine plus nerve growth factor, compound 48/80, substance P, ATP, tetradecanoylphorbolacetate, melittin). The IC50 ranged from 4 microM to 24 microM at concentrations of secretagogues releasing 30-50% of mast cell histamine. However, the potency of the drug decreased at higher secretagogue concentrations. Mast cells, pretreated with apomorphine and washed, released little histamine upon stimulation. The secretory response could be partially restored on increasing the concentration of secretagogues. The results suggest that apomorphine affects a regulatory step controlling the terminal sequence of mast cell secretory activity. As indicated by the reduced potency of the drug, the control by the apomorphine-sensitive reaction loses efficiency under conditions of massive histamine release.     

Immunological modulation of cholinergic histamine release in isolated rat mast cells

Isolated purified rat mast cells release histamine when exposed to acetylcholine according to different patterns of sensitivity. The degree of histamine release is correlated with the levels of reaginic antibodies presumably bound to the mast cell membrane. In fact, mast cells passively sensitized with mouse myeloma IgE against egg albumin or DNP2-lysine, react to acetylcholine with a release of histamine, which is proportional to the IgE concentration in the incubation medium. The histamine release induced by acetylcholine is due to the stimulation of a muscarinic receptor. Accordingly, acetylthiocholine is unable to evoke histamine release and preincubation of sensitized cells with atropine fully inhibits the cholinergic histamine release. The histamine release evoked by acetylcholine is potentiated by the exposure of sensitized cells to the specific antigen. The present results suggest that sensitization of mast cells is a crucial factor in modulating their sensitivity to acetylcholine.     

Effect of methylmercury on histamine release from rat mast cells

Methylmercury chloride (MeHgCl) is well known as a significant environmental hazard, particularly as a modulator of the immune system. As it is acknowledged that the critical effector cells in the host response participating in various biological responses are mast cells, we tried to define the possible contribution of mast cells in the development of methylmercury-evoked effects. We investigated the effects of methylmercury on the rat mast cell degranulation induced by non-immunological stimuli (the selective liberator of histamine, compound 48/80, and calcium ionophore A23187) both in vivo and in vitro. Using the cells prepared from methylmercury-intoxicated rats through a 5-day treatment of MeHgCl (10 mg/kg/day), we observed the suppression of calcium ionophore A23187- and 48/80-induced histamine release, which was enhanced with time after treatment. Similar suppression was observed in the ionophore-stimulated release, when cells were prepared from rat with a single treatment of MeHgCl (20 mg/kg). It should be noted that when cells from the control rat were pre-incubated with methylmercury in vitro at a 10(-8) M concentration for 10 min, A23187 and compound 48/80-stimulated histamine release was significantly enhanced. However, when the pre-incubation period was prolonged to 30 min, the release was suppressed. An increase in the methylmercury concentration to 10(-6) M also suppressed the histamine release. These results show that methylmercury treatment can modify mast cell function depending on concentration and time, and might provide an insight into the role of mast cells in the development of methylmercury-stimulated effects.     

Properties of hydrogen peroxide-induced histamine release from rat mast cells

Incubation of rat peritoneal mast cells with hydrogen peroxide results in a marked release of histamine. Maximal release is observed with 0.05–0.1 mM H₂O₂, but higher concentrations of H₂O₂ instead suppresses the release. Histamine release starts after about 2 min of lag time and reaches a plateau in about 10 min. Hydrogen peroxide-induced release does not exceed 50–60 per cent of total histamine if the incubations are prolonged or additional H₂O₂ is given at 10 min. This would be explained by the fact that H₂O₂ causes impairment of the histamine releasing system of mast cells simultaneously with the release of histamine. Hydrogen peroxide-induced release is not due to nonspecific lysis of the cells because lactate dehydrogenase, a cytoplasmic enzyme, is not liberated during the reaction. The reaction requires the presence of Ca²⁺, is enhanced by D₂O and suppressed by colchicine. It is not, however, affected by dibutyryl cAMP or dibutyryl cGMP. No significant alteration of intracellular levels of cyclic AMP and cyclic GMP is observed during the incubation of mast cells with 0.1 mM H₂O₂. These results indicate that microtubular functions would be involved in the releasing reaction although they are not under the control of cyclic nucleotides. Microscopic observation shows that H₂O₂-induced release is accompanied by degranulation.     

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.     

Dextran-induced release of serotonin from isolated rat peritoneal mast cells

Dextran (9 mg/ml incubate) was found to induce a serotonin (5-HT) release from isolated rat peritoneal mast cells of about 10% within an incubation period of 5 min. at 37 degrees. The extent of release was not increased by using higher concentrations of dextran or by increasing the incubation period from 5 to 20 min. The dextran-induced release of 5-HT was increased to 50-60% when the mast cells were preincubated with phosphatidylserine (PS) in doses of 2.6-4.3 microgram/ml incubate. Higher concentrations of PS alone induced a rapid 5-HT release of approximately 50-60%. The 5-HT release process studied was found to possess both similarities and dissimilarities with the previously described dextran-induced release process of histamine, also studied in isolated rat peritoneal mast cells. The results supported previous indirect evidence of a 5-HT release from mast cells in the early phase of the dextran-induced anaphylactoid reaction in the rat.     

Effects of benzodiazepines on serotonin release from rat mast cells

Ro5-4864, diazepam and chlordiazepoxide inhibited the concanavalin A-induced [14C]serotonin release from rat mast cells dose dependently with IC30 values 38, 115 and 160 microM, respectively. They also inhibited concanavalin A-induced 45Ca uptake, with IC50 values 180, 860 and 1800 microM, respectively. Clonazepam slightly inhibited serotonin release, but medazepam did not, and neither compound inhibited the calcium uptake stimulated by concanavalin A. The potencies of benzodiazepines to inhibit concanavalin A-induced serotonin release and 45Ca uptake were correlated with their binding affinities to the peripheral type of benzodiazepine binding sites. At higher concentrations, these benzodiazepines caused release of both serotonin and lactate dehydrogenase, due to their cytotoxicity. The calcium channels of mast cells are probably not voltage-dependent, as the agonists of voltage-dependent calcium channels, Bay k 8644 and YC-170, did not stimulate serotonin release. Moreover, Ro5-4864, diazepam and chlordiazepoxide inhibited A23187-induced serotonin release. Mast cells have high contents of calmodulin (602 +/- 20 ng/10(6) cells), and benzodiazepines inhibited calmodulin. The benzodiazepine inhibitory effects on the serotonin release induced by A23187 seemed to be partly due to their calmodulin-inhibiting activities. These results suggest that inhibition of serotonin release by benzodiazepines in mast cells activated by concanavalin A is mainly due to inhibition of calcium channels, which may be controlled by the peripheral type of benzodiazepine binding sites.     

Plasma membrane adenosine triphosphatases in rat peritoneal mast cells and macrophages--the relation of the mast cell enzyme to histamine release.

Adenosine triphosphatases activated by calcium or magnesium have been demonstrated on the outer surface of rat peritoneal mast cells and macrophages. The plasma membrane ATPases in the two types of cells have similar but not identical properties. Mg²⁺ is somewhat more effective than Ca²⁺ in stimulating both the enzymes. They are not influenced by sodium and potassium and not inhibited by ouabain and oligomycin. Ethacrynic acid inhibits both, but the mast cell enzyme is more sensitive to it. The enzyme on the macrophage has five to thirty-seven times higher activity (average seventeen times) than that on the mast cell. The apparent K_m of the enzymes in intact cells, incubated with adenosine triphosphate for 5 min, is estimated to be 36 μM for mast cells and 30 μM for macrophages. The optimal pH for the mast cell and the macrophage enzymes is 6.7 and 7.1 respectively. The activities of the two enzymes rise similarly with temperature up to 37° but differ at 47°, the macrophage enzyme being less active at this temperature than at 37°. Phosphatidyl serine, which stimulates anaphylactic and dextran-induced histamine release, causes about 40 per cent stimulation of the plasma membrane ATPase of mast cells in the absence of Ca²⁺ and Mg²⁺ but has no appreciable effect in their presence. No change in the mast cell enzyme could, however, be observed in relation to histamine release induced by dextran, compound $\text{48}\text{80}$ and ATP. But ethacrynic acid, which in 1 mM concentration inhibits 50 per cent of the mast cell enzyme activity, also causes pronounced inhibition of histamine release induced by all the three agents in the same concentration. The inhibition is not influenced by the presence of glucose, suggesting that ethacrynic acid does not inhibit histamine release by blocking energy metabolism. Ethacrynic acid apparently acts at another site. The site of action could very well be plasma membrane ATPase. There is also a correlation between the inhibition of the mast cell enzyme by sodium fluoride and lack of calcium and their inhibitory effect on histamine release. The possible involvement of the plasma membrane ATPase of mast cells in the process of exocytosis leading to histamine release is discussed.     

Turnover of different mast cell pools of histamine in the rat

The uptake and elimination of radiolabelled histamine was studied in the rat duodenum, where histamine is stored in a specific population of mucosal mast cells (MMC), and in the tongue, where histamine is stored in the classic connective tissue mast cell (CTMC). The specific activity of histamine was measured after one i.v. injection of its precursor, 3H-histidine. Decarboxylation of histidine and uptake of histamine occurred in both tissues. The initial specific activity of histamine was very low in the tongue but 5 times higher in the duodenum, while the endogenous duodenal histamine content was 1/6 of that in the tongue. The elimination rate of labelled histamine in the two mast cell pools was very slow. In the tongue, there was no statistically significant decrease in specific activity during the observation period of 16 days. In the duodenum, there was an exponential decrease of prelabelled histamine with an apparent half-life of 9 days. However, part of this decay of radioactivity may be accounted for by increase in the mucosal histamine pool size and MMC death. The results indicate that the rate of histamine elimination from mast cells of both types is very slow, corresponding with previous results obtained from CTMC of the peritoneal cavity.