Antiedematogenic effects of the polar fractions of Persea cordata Mez. (Lauraceae) on microvascular extravasation in rat skin

ETHNOPHARMACOLOGICAL RELEVANCE

Persea cordata Mez. (Lauraceae) is a medicinal plant used in veterinary ethnopharmacology, which is a popular medicine used as an anti-inflammatory and healing agent, mainly on animal skin diseases, characterized by cutaneous open wounds, in South Brazil.

AIM OF THIS STUDY

The purpose of this study was to investigate a possible antiedematogenic effect of ethyl acetate (EtAc) and butanol (BuOH) polar fractions of Persea cordata on Evans blue dye leakage induced by pro-inflammatory agents in rat skin.

MATERIALS AND METHODS

Male Wistar rats (180-200 g, n=5-6) were pretreated with a single intraperitoneal administration of EtAc or BuOH (1 to 600 mg kg(-1)) fractions followed by intravenous Evans blue dye injection (1%, 30 mg kg(-1), i.v.), 60 min before the injection of phlogistic agents. Animals received intradermal injections (0.05 ml) of carrageenan (CAR, 300 µg/site), 48/80 compound (C4880, 10 µg/site), histamine (HIS, 0.3 µg/site), serotonin (5-HT, 0.01 µg/site), dextran (DEX, 200 µg/site), bradykinin (BK, 0.003 µg/site), capsaicin (CPS, 400 µg/site), substance P (SP, 0.003 µg/site) or prostaglandin E2 (PGE2 10 nmol/site) and they were submitted to euthanasia after 60 min. Skin samples were obtained in the extravasation sites of Evans blue dye. Skin fragments were soaked in formamide at 37°C (during 24h) for Evans blue extraction. The amount of dye leakage in the tissue fragment was determined by a spectrophotometer (620 nm).

RESULTS

In a very similar manner in terms of potency and efficacy, systemic administration of EtAc and BuOH fractions caused dose-dependent inhibition of vascular Evans blue dye leakage induced by phlogistic agents in the rat skin. The results obtained (ID50 values in mgkg(-1) and maximal inhibition in %) with EtAc fraction, as follows were: CAR (34.42 and 63.0), 4880 (8.52 and 59.1), HIS (21.22 and 66.8), 5-HT (32.99 and 73.4), DEX (41.74 and 67.0), BK (34.03 and 68.0), CPS (100.7 and 77), SP (2.1 and 78.9) and PGE2 (133 and 71.0). BuOH fraction significantly inhibited CAR (25.9 and 70)-, 4880 (36.8 and 66)-, HIS (17.6 and 77)-, 5-HT (32.8 and 56)-, DEX (89.6 and 75)-, BK (28.0 and 66)-, CPS (136.37 and 71)-, SP (5.6 and 78)- and PGE2 (109.64 and 56)-induced VE, respectively.

CONCLUSION

Systemic administration of Persea cordata polar fractions exerts a non-specific inhibitory effect on microvascular leakage induced by pro-inflammatory agents in rat skin, probably to interfering with different biological systems involved in the development of the inflammatory process, reinforcing the popular use of Persea cordata as an anti-inflammatory and healing agent for skin.

Antipruritic effect of Cnidii Monnieri Fructus (fruits of Cnidium monnieri CUSSON)

Antipruritic effects of 70% ethanol extract (CM-ext) of Cnidii Monnieri Fructus (dried fruits of Cnidium monnieri CUSSON, Umberifferae) were investigated. In mice, an oral administration of CM-ext (200 and 500 mg/kg) inhibited compound 48/80-induced scratching behavior without influence on spontaneous locomotion. Isopimpinellin (3) and osthol (1), coumarin derivatives isolated from CM-ext, showed an inhibitory effect on compound 48/80-induced scratching behavior.

Peritoneal toxicity of water: a model of chronic peritonitis caused by osmotic dysequilibrium in rats

The purpose of this work was to determine whether the osmotic dysequilibrium created by intraperitoneal (i.p.) injection of pure water has any permanent, damaging toxic sequelae. Rats were injected i.p. with pure water on five successive days. Necropsies were performed 1 week after the last injection. Necropsies revealed fibrosis of peritoneal surfaces of liver and spleen, similar to the effects of chemical irritants but milder. The severity of the lesions depended on the dose of water and the number of injections. A few minutes of contact with pure water was sufficient to ensure subsequent development of fibrosis. Soon after the initial injury, the inoculum became less hypotonic and then isotonic. Isotonic or moderately hypotonic electrolyte solutions did not produce peritoneal fibrosis but very hypotonic solutions were toxic. Injection of the synthetic compound 48/80, which is known to cause discharge of mast cell granules, did not produce peritonitis, nor was contamination by endotoxin or by blood responsible for the lesions. Injection of water may be a useful method for investigating the role, if any, of mast cells and/or mesothelial cells in the toxic effects of osmotic dysequilibrium.

The growth of brown adipose tissue in cold-acclimatized rats after depletion of mast cell histamine by compound 48/80

Cold acclimatization (4-5 degree C) is accompanied by 2-3 fold increase of brown adipose tissue (BAT). This rapid growth of interscapular BAT was studied after histamine depletion. In control rats maintained at room temperature (28 +/- 2 degree C) the BAT histamine content was 23.4 +/- 5.9 (mean +/- SD) microgram/g of tissue and cold acclimatization (5 +/- 1 degree C) produced a significant increase of BAT weight, but reduced the histamine content to 8.4 +/- 1.9 microgram/g. The total weight of BAT after 20 days of acclimatization was unaffected by depletion of histamine due to compound 48/80. The low level of histamine in BAT of cold acclimatized rats could be due to a fast rate of amine utilization; alternatively an altered synthesis or storage process may occur during acclimatization.

Augmentation of allergic reactions by several pesticides

The augmentative effects of several pesticides on histamine release from mast cells of rats that had been sensitized passively by anti-dinitrophenol (DNP) monoclonal IgE antibodies were investigated in vitro. Various pesticides, especially phenthoate (PAP), chlornitrofen (CNP) and paraquat (PQ), increased histamine release. This increase was not observed in histamine release with non-antigen or induction by calcium ionophore A23187 or compound 48/80. Passive cutaneous anaphylaxis (PCA) was examined, and an increase of PCA was observed with PAP and PQ, but not with CNP, while an increase of tumor necrosis factor-alpha (TNF-alpha) production was observed with CNP and PQ, but not PAP. These results suggest that various pesticides as environmental pollutants exacerbate allergic diseases.

The mast cell: origin, morphology, distribution, and function

The mast cell remains an enigmatic cell more than 100 years after its discovery by Paul Ehrlich at the turn of the century. It is a cell that is found widely distributed in the body particularly associated with connective tissues. It can be recognised by its content of metachromatic granules when appropriately fixed and stained with metachromatic dyes such as toulidine blue. The metachromatic granules of the mast cell remain an important differentiating characteristic from other cells although it is by no means absolute. In the early days of its discovery it was thought to originate from primitive mesenchyme, thymocyte or lymphocyte. More recent evidence suggests that it may have originated from the monocyte. Current evidence points to an origin from haemopoietic tissue in the bone marrow, the progenitors differentiate from primitive cells under the influence of cytokines (IL3), migrate to other body sites and then undergo differentiation and maturation under the influence of growth and other factors. The mast cell has many functions exerted through its ability to produce a host of biologically active substances the most notable being heparin, serotonin, dopamine, tryptase and chymase. These substances may be released in response to immunological and neural stimuli. Mast cells are found to be functionally heterogeneous, possibly site specific and have the ability to adapt to their environment, producing secretions commensurate with the needs of any situation. The mast cell is involved in immunological, neoplastic, inflammatory and other conditions. Much about its function has been unravelled but there remains more to be uncovered.

Monitoring exocytosis and release from individual mast cells by capillary electrophoresis with laser-induced native fluorescence detection

The complex temporal evolution of on-column exocytotic release of serotonin and proteins from individual rat peritoneal mast cells (RPMCs) was monitored by using capillary electrophoresis. Laser-induced native fluorescence detection with 275-nm excitation was used, and a detection limit of 1.7 amol (S/N = 3; rms) was obtained for serotonin. A physiological running buffer was used to ensure that the cell remained viable throughout. The secretagogue was polymyxin B sulfate (Pmx). Following the injection of a single mast cell into the capillary, electromigration of Pmx toward and past the cell induced degranulation and release of serotonin. The time course of release was registered in the electropherograms with subsecond resolution. Subsequent introduction of SDS caused the cell to lyse completely and allowed the residual serotonin to be quantified. The average amount of serotonin observed per RPMC was 1.6 +/- 0.6 fmol; the average percentage of serotonin released was 28 +/- 14%. Events that are consistent with released serotonin from single submicrometer granules (250 aL each) were evident, each of which contained an average amount of 5.9 +/- 3 amol.

A role for mast cells in adenosine A3 receptor-mediated hypotension in the rat

1. The adenosine A3 receptor agonist, N6-2-(4-aminophenyl)ethyladenosine (APNEA) induces hypotension in the anaesthetized rat. The present experiments were carried out to explore the role of mast cells in the response. 2. Intravenous injection of APNEA (1-30 micrograms kg-1 to rats in which the A3 receptor-mediated response had been isolated by pretreatment with 8-(p-sulphophenyl) theophylline (8-SPT)), induced dose-related falls in blood pressure accompanied at higher doses by small falls in heart rate. Responses to the mast cell degranulating agent, compound 48/80 (10-300 micrograms kg-1, i.v.) were qualitatively similar to those to APNEA. 3. Pretreatment with sodium cromoglycate (0.25-20 mg kg-1, i.v.) induced dose-related, although incomplete, blockade of the hypotensive responses to APNEA. At 20 mg kg-1, sodium cromoglycate also inhibited the cardiovascular response to compound 48/80 but had no effects on those to the selective A1 receptor agonist, N6-cyclopentyladenosine (CPA) or the selective A2A receptor agonist, 2-[p-(2-carboxyethyl)phenylamino]-5'-N-ethylcarboxamidoadenosine (CGS 21680). Lodoxamide (0.01-20 mg kg-1) also blocked selectively but incompletely the response to APNEA. 4. The cardiovascular responses to compound 48/80 (10-300 micrograms kg-1, i.v.) were markedly suppressed in animals which had received repeated doses of the compound by the intraperitoneal route. Similarly APNEA was essentially devoid of cardiovascular activity in such preparations. In contrast, responses to CPA were similar in animals treated repeatedly with compound 48/80 to those obtained in control animals. 5. Plasma and serum histamine concentrations were markedly increased associated with the pronounced hypotensive responses induced by intravenous injections of APNEA (30 or 100 microg kg-1) in the presence of 8-SPT, or compound 48/80 (300 microg kg-1).6. Taken together the data implicate the mast cell in a key role in adenosine A3 receptor-mediated hypotension in the anaesthetized rat.

The inhibitory effect of magnolol on cutaneous permeability in mice is probably mediated by a nonselective vascular hyporeactivity to mediators

In the present study, we demonstrated the inhibitory effect of magnolol on the plasma leakage in passive cutaneous anaphylactic (PCA) reaction, neurogenic inflammation, dorsal skin and ear edema in mice. Hind-paw skin plasma extravasation caused by antidromic stimulation of the saphenous nerve was reduced in mice pretreated with magnolol, diphenydramine or methysergide, but not with indomethacin. Ear edema formation in the PCA reaction was reduced by magnolol in dose-dependent manner. In addition, histamine-, serotonin-, compound 48/80-, bradykinin- and substance P-induced ear edema in mice was also suppressed by magnolol. A dose- and time-dependency of the inhibitory effect of magnolol was demonstrated in histamine- and compound 48/80-induced dorsal skin edema. The maximal inhibitory effect produced by a single dose of magnolol (10 mg/kg) persisted for 1 h, and significant suppression lasted for at least 3 h. In compound 48/80-pretreated mice, the histamine content of the ear was greatly reduced. Bradykinin- and substance P-induced ear edema in compound 48/80-pretreated mice was less severe than that seen in normal mice, but was still significantly reduced by magnolol pretreatment. Moreover, the inhibitory effect of magnolol was more marked than that of diphenhydramine combined with methysergide. These results suggest that the inhibitory effect of magnolol on local edema formation probably occurs through a nonselective inhibition on vascular tissue to prevent the permeability change caused by various mediators.

Active translocation of platelets into sinusoidal and Disse spaces in the liver in response to lipopolysaccharides, interleukin-1 and tumor necrosis factor

1. Injection of lipopolysaccharides (LPS) or endotoxin into mice and rats induces a prolonged increase in serotonin (5-hydroxytryptamine: 5HT), predominantly in the liver. 2. The 5HT increase reflects the accumulation of platelets in the sinusoidal and perisinusoidal Disse spaces (spaces between endothelial cells and hepatocytes) in the liver. 3. Most of the platelets which accumulated in these spaces still retained their intact structure and a large amount of 5HT. 4. Interleukin-1 and/or tumor necrosis factor also induce the platelet response. 5. Kupffer's cells play a key role in this platelet response. 6. Anti-platelet drugs currently used, except for anti-inflammatory steroids, were ineffective in preventing the platelet response. 7. This platelet response is different from the well known platelet aggregation. 8. The possible involvement of this platelet response in insulin-independent hypoglycaemia, disseminated intravascular coagulation, septic shock, hepatitis, Shwartzman type reactions or self-defense mechanisms is discussed.

The effect of lipopolysaccharide, interleukin-1 and tumour necrosis factor on the hepatic accumulation of 5-hydroxytryptamine and platelets in the mouse

1. Injection of lipopolysaccharide (LPS; 0.5-500 microgram kg-1) into mice induced a dose-dependent, slowly developing increase in hepatic content of 5-hydroxytryptamine (5-HT). This sustained increase could not be attributed to an LPS-induced alteration of the pharmacokinetic handling of 5-HT by stimulation of its uptake or inhibition of its degradation. 2. Regional differences were apparent in the tissue content of histamine and 5-HT between mast cell-deficient (W/Wv) and normal (+/+) mice. LPS administration (0.5 mg kg-1) gave comparable increases in the hepatic level of 5-HT in mast cell-deficient and normal mice. 3. Reserpine pretreatment (1 mg kg-1) selectively reduced 5-HT levels in the blood, spleen, liver, brain and lung of normal mice. Prior treatment with this agent also abolished the LPS (0.5 mg kg-1)-induced hepatic accumulation of 5-HT. 4. Accumulation of 5-HT in the liver by LPS (0.1 mg kg-1) was temporally associated with both a fall in the levels of circulating platelets, and a reduction in the concentration of 5-HT in the blood. The LPS dose-dependent (0.5-500 micrograms kg-1) increase in hepatic 5-HT content was associated with a similar dose-dependent reduction in the circulating levels of 5-HT. 5. Interleukin-1, alpha and beta (10 micrograms kg-1) and tumour necrosis factor alpha (TNF alpha) (1 mg kg-1) significantly enhanced the accumulation of 5-HT within the liver. Administration of TNF alpha (10 micrograms kg-1) potentiated the increase in hepatic 5-HT content seen with IL-1 beta (10 micrograms kg-1). 6. Electron microscopy revealed numerous platelets in the sinusoidal and perisinusoidal Disse spaces within the liver, in animals pretreated with LPS (0.1 mg kg '). The platelets retained their intact structure and showed no evidence of degranulation. 7. These data suggest that the LPS and cytokine-induced mobilization of 5-HT in the liver is associated with the hepatic translocation of platelets. This migration appears to be independent of platelet aggregation.

Characteristics of histamine release from rat mast cells induced by a bracken toxin, braxin A1

The effect of braxin A1, a new bracken glucoside, on histamine release from isolated rat peritoneal mast cells was studied. Braxin A1 caused the release of histamine in a dose-dependent manner; the release was slow and increased gradually with time, finally reaching a maximum release of 100%. The action of braxin A1 depended on the incubation temperature in the range from 4 degrees C to 49 degrees C, while it was almost abolished at 0 degree C. The action of braxin A1 was unaffected by removing calcium or any inorganic ions from the incubation medium and by the addition of 2,4-dinitrophenol or theophylline. The mast cells exposed to braxin A1 were vitally stained with trypan blue and swelled greatly. The cell swelling was characterized by the protrusion of swollen cytoplasmic granules. The present results for braxin A1 were similar to those for the ionophore X537A except for the extracellular inorganic ion dependency, but they were different from those observed with compound 48/80. These results suggest that braxin A1 releases histamine from mast cells without both exocytosis and membrane lysis, but with a cytotoxic action on cytoplasmic membranes by a different mode of action from that of X537A.

Release of 5-hydroxytryptamine, dopamine and noradrenaline in the rat vas deferens in the presence of compound 48/80, veratridine or K+

1. The release of 5-hydroxytryptamine (5-HT), dopamine and noradrenaline (NA) from the rat isolated vas deferens was estimated by high performance liquid chromatography with electrochemical detection. 2. Compound 48/80, which is known to release 5-HT and histamine from mast cells, induced a concentration-related, rapid overflow of 5-HT from the rat isolated vas deferens, releasing about 50% of the 5-HT present in the tissue at a concentration of 300 micrograms ml-1. The drug did not induce the release of either dopamine or NA. 3. The depolarizing agents veratridine (10 microM) or K+ (100 mM) induced the release of 5-10% of the 5-HT present in the vas deferens, but did not evoke the overflow of 5-HT from isolated mast cells. 4. Veratridine induced the release of a greater proportion of the dopamine than of the NA contained in the vas deferens (41.0 +/- 5.5 vs 17.9 +/- 2.0%, after 20 min of exposure to the drug, n = 6). In contrast, K+ evoked the release of both amines equally. 5. It is concluded that in the rat vas deferens 5-HT is stored in mast cells and also in cells responsive to depolarizing stimuli. It is suggested that 5-HT could be a neuromodulator or a neurotransmitter in this organ. Veratridine and K+ induce the release of dopamine in addition to NA.

The depletion effects of chlorpromazine, reserpine and ascorbic acid on tissue histamine of guinea-pigs

1. 30 mg kg-1 chlorpromazine (CPZ) depleted more than half of the tissue histamine from lungs, stomach, ileum and skin of the normal guinea-pigs. However, the drug increased the tissue histamine content in scorbutic animals. 2. In contrast, reserpine depleted histamine from the four tested tissues in both normal and scorbutic animals, except those in the lungs of the control animals. 3. Ascorbic acid only depleted histamine from the stomach and ileum. 4. A 24 hr period was the time limit for CPZ to deplete the histamine in all the four tested tissues. 5. Histamine partially or completely recovered in the tissues after the next 24 hr.

A pharmacologic study on the histamine releasing effect of atracurium and other muscle relaxants in rat isolated ileum

In this study, the effects of histamine, antihistamines (terfenadine and mepyramine), 5-hydroxytryptamine, and muscle relaxants, atracurium, vecuronium and gallamine, on the tone and contractility of rat ileum were studied and compared in vitro. The aim of the present investigation was to measure, pharmacologically, the histamine releasing effect of muscle relaxants, e.g atracurium, vecuronium and gallamine, by comparing their contractile response in the absence and presence of antihistamines and comparing their mechanical responses with those produced by histamine and 5-hydroxytryptamine (5-HT). The results showed that the antihistamines, triludan(terfenadine) and mepyramine produced opposite effects in rat ileum. Terfenadine (0.1-20 microM) produced concentration-dependent contractions in the rat ileum, whereas mepyramine (0.1-10 microM) relaxed the muscle, e.g. by 1.2 g tension. Atracurium (0.5-500 microM), vecuronium (0.2-200 microM), and gallamine (0.1-7.0 microM) produced marked contractions (1.5-4.0 g tension) in rat ileum, and these contractions were markedly reduced by mepyramine (1.3 microM) or terfenadine (5 microM), implicating histamine release in the generation of these contractions. However, there was some residual contraction which was not blocked by mepyramine, but by 5-HT antagonist, methysergide (1 microM), indicating that a mechanism other than histamine release may be responsible for the residual contraction, i.e. release of other mediators such as 5-HT, prostaglandins, or calcium. 5-HT (0.5-500 microM) and histamine (0.5-500 microM) produced contractions in the rat ileum, but 5-HT was more effective than histamine in producing these contractions. Similarly, gall amine was more effective than atracurium and vecuronium in contracting the rat ileum.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Induction in the guinea pig of delayed hypersensitivity to compound 48/80

Intradermal injection of compound 48/80 into the nuchal area of the guinea pig in an adjuvant/water emulsion induced strong delayed hypersensitivity. Groups of 8 animals were injected weekly for 3 weeks with 100 microliter of 10%, 1%, 0.1% or 0% of compound 48/80 in the adjuvant/water emulsion. 6 of 8 animals in the highest concentration group died between 1 and 24 h after the first injection. The other concentrations produced no visible evidence of acute toxicity. 2 weeks after the last injection, the animals were challenged with an open topical application of 1%, 0.1%, 0.01%, and 0% of compound 48/80 in 3:7 propylene glycol/ethanol. The strongest reactions were found in the 0.1% induction group. Some degree of immunologic tolerance may have occurred in the 1% induction group resulting in somewhat weaker challenge responses.

Degranulation of mast cells and inhibition of the response to secretory agents by phototoxic compounds and ultraviolet radiation

The symptoms of cutaneous phototoxicity from coal tar compounds and the nonsteroidal anti-inflammatory drug benoxaprofen are characterized by wheal and flare formation which is mediated by histamine released from dermal mast cells. Rat serosal mast cells were used as an in vitro model system to study the direct effect of phototoxic compounds on mast cell degranulation. The coal tar compounds studied included acridine and pyrene. Combined exposure of cells to acridine and UVA (320 to 400 nm) radiation caused mast cells to degranulate, as assayed by the release of [3H]serotonin. Maximum [3H]serotonin release (70 to 80%) was obtained with 50 microM acridine and 300 kJ/m2 UVA. Pyrene (25 microM), when photoexcited with UVB (280 to 360 nm) radiation, caused about 80% release of [3H]serotonin. No degranulation occurred with 20 microM benoxaprofen and UVB doses up to 7.2 kJ/m2. Trypan blue staining correlated well with degranulation caused by acridine plus UVA; however, with pyrene plus UVB there was greater [3H]serotonin release than dye uptake. Excitation of photosensitizers with doses of UV radiation that did not cause trypan blue staining suppressed degranulation of mast cells in response to chemical stimulation. Acridine, pyrene, and benoxaprofen in the presence of UV radiation inhibited the mast cells from responding to compound 48/80 or the calcium ionophore, chlortetracycline. Two other phototoxic compounds, chlorpromazine and deoxytetracycline, also abolished degranulation by compound 48/80. These findings indicate that phototoxic compounds: (1) cause degranulation in the presence of high doses of UV radiation; and (2) suppress degranulation of mast cells in response to secretory stimuli at doses of UV radiation that do not cause release of mediator.

Histamine release by compound 48/80: evidence for the depletion and repletion of calcium using chlortetracycline and 45calcium

Selective release of histamine from rat peritoneal mast cells in vitro was induced by compound 48/80 (1 microgram/ml). Most of the release (75-80%) occurred in a calcium(Ca)-free medium but optimum release was obtained in the presence of 0.9 mM Ca. The release in Ca-free medium still occurred after 180 min incubation. However, prolonged incubation (180 min) in a medium containing chelating agents (EDTA or EGTA) resulted in complete inhibition of histamine release, loss of fluorescence seen with chlortetracycline (CTC) and loss of previously loaded 45Ca from the mast cells. Addition of Ca to these cells resulted in rapid restoration of fluorescence with chlortetracycline. There was also a rapid uptake of 45Ca. Partial depletion of cellular Ca (60 min incubation with EDTA) reduced the rate as well as the amount of histamine release by compound 48/80. These data provide direct evidence for the depletion of cellular Ca which is utilized by compound 48/80 to induce histamine release.

Early kinetics of Ca2+ fluxes and histamine release in rat mast cells stimulated with compound 48/80

The kinetics of Ca2+ uptake and efflux have been measured in rat peritoneal mast cells stimulated with compound 48/80 using rapid mixing and a silicone oil centrifugation technique. Responses at one-second time intervals were resolved beginning as early as three seconds after initial stimulation. The results clearly demonstrate that Ca2+ uptake occurs after the initiation of histamine release. Ca2+ efflux occurs simultaneously with histamine release. The implications of these findings are discussed and the technique is described.

Some studies on the release of histamine from mast cells treated with polymyxin

Polymyxin B produced a dose-dependent release of histamine from rat peritoneal mast cells. The response was non-cytotoxic and extremely rapid. The release was maximal in the presence of extracellular calcium ions but a substantial component persisted in the absence of the cation. This component was virtually abolished by pretreatment with the ionophore A23187 in the presence of a chelating agent and thus probably reflected the mobilization of intracellular stores of calcium. Hamster peritoneal cells also responded to polymyxin but were less reactive than those of the rat. Mouse peritoneal cells and guinea-pig lung mast cells responded only at very high concentrations. These results further emphasize the functional heterogeneity of mast cells from different sources. Histamine release from rat peritoneal mast cells was inhibited in dose-dependent fashion by cAMP analogues and anti-allergic drugs. The inhibitory effect varied inversely with the magnitude of the control secretion. With the exception of disodium cromoglycate, the test drugs were essentially equiactive in the presence and absence of extracellular calcium. These results are discussed in terms of the possible mode of action of these compounds.

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.

Evidence for intracellular histamine liberation in isolated rat mast cells

The beta-adrenoceptor blocking drug exaprolol liberated histamine from isolated rat mast cells in a dose- and time-dependent way. Histamine was liberated within seconds and was not followed by a parallel granule liberation. The inhibition of histamine liberation was induced with low temperature, low pH, high concentration of Ca2+, TTD, suramin and EDTA. Subcellular distribution of 3H-exaprolol demonstrated a quantitative relationship between histamine depletion against exaprolol uptake in isolated rat mast cell granules. A nonspecific mechanism of action in the effect of exaprolol on mast cells is discussed. It is proposed that the drug acts on mast cells due to the direct and indirect ion exchange mechanism resulted in disproportion between histamine and granule liberation.

IgE-mediated 14C-serotonin release from passively sensitized rat mast cells: comparative kinetic study with formaldehyde and ice-cold methods

The kinetics of IgE-mediated release of serotonin from passively sensitized rat mast cells in vitro was studied by stopping 14C-serotonin release with the application of formaldehyde fixative or ice-cold mast cell medium (MCM). Antigen dose-release curves of 14C-serotonin and/or histamine were comparable when mediator release was terminated with either formaldehyde at a final concentration of 1% or ice-cold MCM 15 min after antigen challenge. However, the kinetic study of immunological mediator release stopped by formaldehyde showed that the addition of antigen resulted in a progressive increase of released 14C-serotonin for 7 min, the release curve being sigmoidal, whereas the application of ice-cold MCM artificially enhanced 14C-serotonin and histamine release in the first 2 min. The results suggest that stopping IgE-mediated release of 14C-serotonin with formaldehyde is a simple, rapid and accurate method of studying the kinetics of mediator release from mast cells.

Effect of disodium cromoglycate and cyclic AMP-active drugs on cytotoxic histamine release from rat mast cells

Disodium cromoglycate and compounds which elevated levels of cyclic AMP in the mast cell variously inhibited cytotoxic histamine release induced by the surface active agents melittin, Tween 20 and Triton X-100. These results are inconsistent with the postulated effects of the drugs on receptor mediated calcium channels and alternative explanations of their action are considered.

Mechanism of action of fire ant (Solenopsis) venoms. I. Lytic release of histamine from mast cells

The mechanism of histamine release from rat mast cells by whole venom from Solenopsis geminata and S. invicta or by 2-methyl-6-undecylpiperidine HCl (C11) was investigated. Histamine release stimulated by one or more of these agents (1) occurred in normal and metabolically inactivated cells, (2) had a biphasic time course in normal and inactivated cells, (3) was temperature dependent and did not occur at 0 degrees C, (4) was accompanied by concomitant cytoplasmic enzyme release, (5) was accomplished by substantial cell swelling, and (6) was correlated with a loss of cell refractility in phase contrast microscopy. These results indicate that C11 causes initial permeability changes in the plasma membrane followed by lytic release of histamine and other cell components. The nonspecific nature of this action of the dialkylpiperidine component of the venoms provides the fire ants with a defense of general applicability.

Quantitative correlation between histamine and 35S release from isolated rat mast cells due to the beta-adrenergic blocking drug Kö 1124

An attempt was made to explain the mechanism of histamine release from isolated rat mast cells induced by the beta-adrenergic blocking drug Kö 1124. This drug at the highest concentration used released 12 times more histamine than most other investigated beta-blockers. The release of histamine with Kö 1124 was dose and temperature dependent. The maximal histamine release was at pH 8 and in the absence of calcium ions. Increased calcium concentration decreased histamine release significantly. The effect of Kö 1124 on histamine release from mast cells was inhibited only by cocaine and 2,4-dinitrophenol; other metabolic inhibitors were ineffective. The histamine release due to Kö 1124 was not followed by an equal release of 35S. Isoprenaline in equimolar concentration decreased histamine release induced by Kö 1124 significantly. The release of 35S-labelled granules was decreased or blocked by isoprenaline.

Enzymes of the mast cell granule

Rat mast cell granules contain a spectrum of enzymes as established by histochemical techniques and subcellular fractionation. However, 35% of the beta-glucuronidase, 30% of the beta-D-galactosidase, 14% of the beta-hexosaminidase and all of the acid phosphatase is not available for immunologic release from purified rat serosal mast cells, suggesting the presence of nonsecretory lysosomes containing these acid hydrolases. On the other hand, immunologic release of the majority of chymase, beta-hexosaminidase, beta-glucuronidase, beta-D-galactosidase, and arylsulfatase A occurs in parallel with histamine and thereby localizes these substances to the rat mast cell secretory granule. A molecular model of the secretory granule in the resting mast cell can now be constructed in which heparin proteoglycan is the granule matrix to which chymase and probably other proteins are ionically bound. Inhibition of chymase by serotonin stored in its active site and of chymase and acid hydrolases by their interaction with heparin probably occurs. Histamine is stored by ionic linkage to carboxyl groups of protein and heparin. Micromolar amounts of heparin glycosaminoglycans, histamine, serotonin, chymase, beta-D-hexosaminidase, beta-glucuronidase, and arylsulfatase A in secretory granules of 10(6) mast cells are 0.7--1.3 x 10(-3), 70--220 x 10(-3), 0.9--28 x 10(-3), 0.2--0.5 x 10(-3), 0.9--2.7 x 10(-6), 0.1--0.3 x 10(-6) and less than 8 x 10(-6), respectively. In addition, the total protein available for calcium ionophore-induced release from 10(6) rat mast cells is about 60 microgram, indicating that less than 50% of the granule protein can be accounted for. Recognition that mast cell secretory granules contain acid hydrolases indicates that they are modified lysosomes; their special intracellular and extracellular functions are dictated by the associated novel constituents and the stimulus for activation.

An automated fluorimetric assay for the simultaneous determinations of histamine and 5-hydroxytryptamine released from rat mast cell preparations

An automated assay suitable for the extraction and simultaneous fluorimetric determination of histamine and 5-hydroxytryptamine (5-HT) released from rat isolated peritoneal mast cells is described. The method gave good reproducibility and accuracy in use and required a sample volume of 0.5 ml for assay at a sampling rate of 30/h. The system was evaluated by assessment of its performance in the determination of histamine and 5-HT released from rat mast cells in response to compound 48/80. The detection limit for the procedure was 2 ng 5-HT base/ml and 20 ng histamine base/ml.

Histamine content of peritoneal and tissue mast cells of growing rats

The histamine and 5-hydroxytryptamine (5-HT) content of mast cells was measured in rat peritoneal mast cells (isolated by density-gradient centrifugation or in crude peritoneal cell suspensions) and in some solid, mast-cell-rich tissues (tongue, skin, and duodenum). The duodenum contains large numbers of mast cells belonging to the specific type of mucosal mast cell. The peritoneal cavity, tongue, and skin contains the classical, mature connective-tissue-type of mast cell. The approximate amine content in mast cells of solid tissues was calculated by combining the biochemical assays with cell counting. The amine content was related to the age and body weight of the rats, studied during a period of rapid body growth (25-233 days). In the connective-tissue-mast cells both amines showed an increase that was strongly correlated to age and body weight. The increment of histamine was not as large as that of 5-HT. In peritoneal mast cells the histamine content per cell was doubled during the growth period studied, whereas there was a sixfold increase of 5-HT. The estimated 5-HT content per mast cell of tongue and skin also increased in relation to body weight. The histamine/5-HT quotients in these tissues were similar, and decreased with increasing age as did the same quotients for peritoneal cells. Parallel cell counts and histamine assays indicated that the mucosal mast cells contained much less histamine than the connective-tissue mast cells, and this findings was supported by histochemical observations. The observations did not suggest that histamine is stored else-where than in mast cells. In the mucosal mast cells, too, the histamine content appeared to increase as a function of age and body weight. Duodenal 5-HT, which is to a large extent contained in enterochromaffin cells, did not increase in relation to body growth.

Histamine-releasing effect of a corticotrophin derivative. II. Mechanism of action of histamine release by C 44 680-Ba, compared with that of Cpd. 48/80, dextran and triton

The mechanism of the histamine-liberating action of the synthetic polypeptide C 44 680-Ba, an alkyl-prolyl derivative of beta 1-19 corticotrophin, was investigated and compared with those of Compound 48/80, dextran, Melittin and Triton X-100. It was found that the release of histamine from rat peritoneal cells induced by the polypeptide is dependent on temperature, pH, calcium ions and energy-providing processes. In regard to these criteria, the mode of action of this histamine liberator resembles that of Compound 48/80 but is quite distinct from that of the unspecific substance Triton X-100.

Role of 5-hydroxytryptamine in the vasoconstrictor action of compound 48/80 in the rat femoral vasculature

1. The effect of compound 48/80 on the rat femoral vasculature was examined by means of a cross-circulation technique. 2. Intra-arterial injection of increasing doses (1.5 to 15 microgram) of compound 48/80 caused dose-dependent vasoconstriction preceded by transient vasodilatation. The vasoconstriction was significantly reduced in reserpine-treated preparations and converted to vasodilatation by methysergide. 3. When the vasoconstrictor response to a large dose (300 microgram) of adenosine was abolished by repeated administration, the response to compound 48/80 remained unaltered. 4. The present results indicate that the femoral arterial vasoconstriction by compound 48/80 in the rat is mediated by the release of 5-hydroxytryptamine (5-HT); this 5-HT may be liberated from a different storage site from that released by adenosine.

Ultrastructural localization of peroxidase in leukocytes of rat bone marrow and blood

The differentiation of leukocytes in the bone marrow and blood of normal adult male rats was studied by electron microscopy and peroxidase cytochemistry. Tissue samples were fixed in glutaraldehyde, or paraformaldehyde-glutaraldehyde, and incubated in a peroxidase medium containing 3,3'-diaminobenzidine and H2O2 ad pH 7.6. Mature cells of blood were identified, and then the earlier stages of maturation in bone marrow were analyzed. In immature cells of four cell lines, neutrophils, monocytes, basophils, and eosinophils, peroxidase is synthesized and could be demonstrated in the rough endoplasmic reticulum (RER), Golgi complex, and in cytoplasmic granules. Later in maturation, reaction product for peroxidase could not be found in RER or Golgi complex, indicating that peroxidase synthesis had ceased. In two cell lines, neutrophils and monocytes, peroxidase-negative granules were formed, and the mature cells contained two populations of cytochemically distinct granules. All granules of mature eosinophils were peroxidase-positive. In mature basophils, some granules were clearly peroxidase-positive; others displayed variable density, making interpretation uncertain. Mast cells were never seen in blood, but were abundant in bone marrow; peroxidase was never found in their granules by either electron microscopic cytochemistry or a variety of light microscopic methods. Hence, these cells differ from basophils, not only in morphology but also in the enzyme content of their granules.

Some pharmacological properties of the venom, venom fractions and pure toxin of the yellow-bellied sea snake Pelamis platurus

The effects of the crude venom, four partially purified venom fractions and pure toxin (Pelamis toxin alpha) from yellow-bellied sea snake, Pelamis platurus, on respiration, blood pressure, heart and skeletal muscle of rabbits have been examined. Results indicated that crude venom, a partially purified toxic fraction and Pelamis toxin alpha caused initial respiratory stimulant effects followed by respiratory paralysis. In most cases, respiratory paralysis occurred before a profound fall in arterial pressure. Depression of the twitch response to nerve stimulation was observed in the tibialis anterior muscle. No significant change in the electrocardiogram was seen. Three partially purified non-toxic fractions of the crude venom induced transient respiratory stimulant effects. It was concluded that the crude venom and Pelamis toxin alpha had an identical mode of action and that they caused respiratory paralysis in rabbits.