Mast cells in the focus of an acute infectious inflammation]

On the model of E. coli-induced acute infectious peritonitis in rats it is established that the mast cell reaction and histamine level increase in exudate and inflamed mesentery tissue are biphase and are observed predominantly following the inflammatory agent action, in the period corresponding to the immediate phase of peritoneal cavity vessel permeability increases. The preliminary elimination of mast cells significantly inhibits a rise in the vascular permeability in the immediate phase and slightly affects the delayed phase, thus prolonging exudation. At the same time the dynamics of free histamine indicates its direct involvement in mediation and/or modulation as well as in subsequent inflammatory events. The common rules of mast cell involvement and vascular permeability increase in infectious and aseptic inflammation have been shown.     

Mast cells of the lungs in experimental hyperergic pleurisy

Reaction of mast cells, the content of free and cell histamine and serotonin in the lung tissue at early stage of inflammation were studied on the model of hyperergic pleurisy in albino rats. Intrapleural antigen injection to sensitized rats was followed by progressive degranulation of mast cells of pleural and subpleural lung tissue with release of histamine and serotonin. The maximal increase in the content of free amines was found after 15 min. The level of free amines did not differ significantly from the initial one by the first hour. The early activation of amines synthesis and their storage recovery were observed as well as reactions of the late phase of immunological activation in the mast cells as a leukocytic tissue infiltration by subsequently polymorphonuclear leukocytes and macrophages.     

Increased pulmonary vascular resistance and permebility due to arachidonate metabolism in isolated rabbit lungs

Liberation and metabolism of arachidonic acid may be the common final pathway of different stimuli on the pulmunary vascular bed. In a model of isolated, ventilated rabbit lungs, perfused with krebs Henseleit albumin buffer in a recirculating system, changes of pulmonary vascular resistance and of vascular permeability are monitored continously. The addition of free arachidonic acid or of the Ca-ionophore A 23187 to the perfusion fluid consistently evokes a biphasic increases in vascular resistance as well as an initially reversible increase in vascular permeability, followed by pulmonary edema. Both phases of increased vascular resistance are completely suppressed by inhibition of the cyclooxygenase, decreased to a large degree by inhibitors of thromnoxane synthetase, and markedly augmented by short preincubation of arachidonic acid with ram seminal vescular microsomes and by sulfhydryl reagents. The increased pulmonary vascular permeability is augmented by inhibition of cyclooxygenase and reduced by simulteneous lipoxygenase inhibition. Antagonists of histamine, serotonin and sympathic or parasympathic activity do not have any influence.PG F_2α, TxB E₂ and PG I₂ alter the pulmonary vascular resistance, but do not increase vascular permeability.In inclusion, increased availability of free arachidonic acid evokes a rise in pulmonary vascular resistance, which can be ascribed to cyclooxygenase products, especially to thromboxane, and causes a rise in vascular permeability which can be ascribed to lipoxygenase products.The findings may be related to acute pulmonary lesions with increase in vascular resistance and with vascular leakage.     

Increased pulmonary vascular resistance and permeability due to arachidonate metabolism in isolated rabbit lungs

Liberation and metabolism of arachidonic acid may be the common final pathway of different stimuli on the pulmonary vascular bed. In a model of isolated, ventilated rabbit lungs, perfused with Krebs Henseleit albumin buffer in a recirculating system, changes of pulmonary vascular resistance and of vascular permeability are monitored continuously. The addition of free arachidonic acid or of the Ca-ionophore A 23187 to the perfusion fluid consistently evokes a biphasic increase in vascular resistance as well as an initially reversible increase in vascular permeability, followed by pulmonary edema. Both phases of increased vascular resistance are completely suppressed by inhibition of the cyclooxygenase, decreased to a large degree by inhibitors of thromboxane synthetase, and markedly augmented by short preincubation of arachidonic acid with ram seminal vesicular microsomes and by sulfhydryl reagents. The increased pulmonary vascular permeability is augmented by inhibition of cyclooxygenase and reduced by simultaneous lipoxygenase inhibition. Antagonists of histamine, serotonin and sympathic or parasympathic activity do not have any influence. PG F2alpha., TxB2, PG E2 and PG I2 alter the pulmonary vascular resistance, but do not increase vascular permeability. In conclusion, increased availability of free arachidonic acid evokes a rise in pulmonary vascular resistance, which can be ascribed to cyclooxygenase products, especially to thromboxane, and causes a rise in vascular permeability which can be ascribed to lipoxygenase products. The findings may be related to acute pulmonary lesions with increase in vascular resistance and with vascular leakage.     

Modeling microcirculatory disorders using an ultraviolet laser]

Reactions of microvessels and mast cells to laser irradiation were studied in rat mesentery by applying the method of intravital microscopy. An ultra-violet laser (gamma=337 nm) was used. The diameter of the laser beam was changed from 2 to 100 mum. Different irradiation doses provoked either an increase of vascular permeability or thrombus formation or hemorrhage. Apart from the vascular wall injury, factors accompanying the damage of red blood cells and other cells of the blood may play a role in the process of thrombus formation. Changes of the vascular diameter and permeability after laser irradiation of mast cells are probably connected with the release of histamine and serotonin contained in them.     

Effect of LY53857, a selective 5HT2 receptor antagonist, on 5HT-induced increases in cutaneous vascular permeability in rats

Both serotonin and histamine increased cutaneous vascular permeability in rats; however, serotonin was approximately 100-fold more potent than histamine. LY53857 (0.1 and 1.0 mg/kg, i.p.), a selective 5HT2 receptor antagonist, blocked serotonin- but not histamine-induced increases in cutaneous vascular permeability. the alpha 1 receptor antagonist, prazosin, did not significantly affect increases in vascular permeability produced by serotonin. These data extend previous studies with LY53857 by further documenting its selectivity as a 5HT2 receptor antagonist. In addition, these results with a selective 5HT2 receptor antagonist provide evidence that 5HT2 receptor activation may be the predominant mechanism associated with vascular permeability changes induced by serotonin.     

Interactions of mast cells and leukocytes in increased vascular permeability in the focus of inflammation]

On the model of acute infectious peritonitis in rats it is shown that the mast cell depletion affected the inflammatory focus vascular permeability mainly in the immediate phase of its increase. Leukopenia inhibited the permeability both in the immediate and delayed phases. The combined depletion of mast cells and leukocytes not only inhibited the degree of vascular permeability increase but strongly affected its kinetics during exudative phase of peritonitis. The results indicate that in the natural conditions of inflammation the mast cell-leukocyte interaction in the vascular permeability increase takes place.     

Absorption and release of biogenic amines by the lung during the restorative period after hypovolemic hypotension

The processes of serotonin and histamine absorption and release by the lungs were studied in dogs during 1 to 3.5 hour hypovolemic hypotension and during 24 hours after blood retains fusion. Absorption of biogenic amines by the lungs tended to increase in all the animals under hypovolemic hypotension. In the group of non-survivors the serotonin absorption by the lungs in the post-terminal period remained increased, while in the group of survivors it came down to normal soon, though the histamine release was increased. The above processes were aggravated in the group of animals whose lungs were affected by oleic acid. It resulted in the absorption of histamine instead of its release. The intensified absorption of biogenic amines by the lungs was accompanied by a quick fall in cardiac output, by the increase in resistance of systemic and pulmonary circulation.     

Biogenic amine content and the pathomorphological shifts in different organs and tissues in a period of the hematogennic spread and fixation of botulin toxin]

In experiments on cats it was shown that 30 minutes after intravenous injection of botulinum toxin, type C, there was a fall in the catecholamine and histamine contents with a simultaneous increase of serotonin in various structures of the brain and spinal cord and in a number of inner organs as well. The metabolic changes in the biogenic amines were combined with certain pathomorphologic changes seen in the form of acute swelling, chromatolysis, destruction of some neurons of the spinal cord and brain, distrophic changes in inner organs, and an increased permeability of the blood-tissue barriers. Marked biochemical and pathomorphologic changes in the spinal cord and brain where the minimum concentration of toxin becomes manifest during its spreading allow a conclusion that botulinum neurotoxin shows its pathogenic action through a disturbed metabolism of biologically active substances.     

Effect of phenoxybenzamine on mesenteric blood flow in irradiated rats

Reactivity of the superior mesenteric artery has been studied in rat Wistar by infusion of biogenic amines (noradrénaline, dopamine, serotonin, acetylcholine and histamine) in presence of phenoxybenzamine. A decrease in reactivity of the post-synaptic alpha receptor located on the mesenteric vascular smooth muscle cell was seen three days after irradiation by 2 Kr.     

Prolonged effect of a single serotonin treatment in adult age on the serotonin and histamine content of white blood cells and mast cells of rats

Hormonal imprinting was provoked by serotonin treatment in adult age. Three weeks after treatment with 100 microg serotonin, the serotonin and histamine content of peritoneal cells (mast cells, lymphocytes and the monocyte-macrophage-granulocyte group), white blood cells (lymphocytes, granulocytes and monocytes) and thymic lymphocytes was studied by flow cytometry. The content of both amines was significantly higher in the mast cells of males and lower in females. Blood lymphocytes contained a higher serotonin and histamine level in males, and a lower serotonin level in females. The peritoneal monocyte-macrophage-granulocyte group contained less serotonin in both males and females. Thymocytes contained higher levels of both amines in females and higher histamine level in males. The experiments demonstrate that a single treatment at adult age can provoke imprinting, which alters-in the present case-the serotonin and histamine content of immune cells durably.     

Effect of leukotrienes B4, C4, and D4 on segmental pulmonary vascular pressures

Leukotrienes (LTs) C4 and D4 are vasoconstrictors and are thought to increase both systemic and pulmonary vascular permeability. However, we and others have observed that LTC4 and LTD4 cause pulmonary vasoconstriction but do not increase the fluid filtration coefficient of excised guinea pig lungs perfused with a cell-depleted perfusate. To determine what vascular segments were exposed to an LT-induced increase in intravascular hydrostatic pressure we measured pulmonary arterial (Ppa), pulmonary arterial occlusion (Po,a), venous (Po,v) and double occlusion (Pdo) pressures in isolated guinea pig lungs perfused with a cell-depleted buffered salt solution before and after injecting 4 micrograms of LTB4, LTC4, or LTD4 into the pulmonary artery. All three LTs increased airway pressures and also increased Ppa, Po,a, and Pdo. Histamine (15 micrograms) as well as serotonin (20 or 200 micrograms) had the same effect. In excised rabbit lungs, histamine and serotonin increased only Ppa, and Po,a. LTC4 had no vasoactivity. There are marked species variations with regard to the activity and site of action of histamine, serotonin, and LTC4 on the pulmonary circulation.     

Analysis of tumor-promoter-induced inflammation in rats: participation of histamine and prostaglandin E2

Inflammatory reactions induced by TPA (12-O-tetradecanoylphorbol 13-acetate)-type tumor promoters, including TPA, teleocidin and aplysiatoxin, and chemical mediators responsible for such inflammatory reactions were analyzed. The tumor promoter dissolved in a 0.8% sodium carboxymethyl cellulose solution was injected into a subcutaneous air pouch preformed on the dorsum of rats. Within 30 min after the injection, vascular permeability as measured by the leakage of labeled albumin into the pouch fluid was increased, with a concomitant increase in histamine level. This increase in vascular permeability was inhibited by a histamine antagonist, pyrilamine, and a serotonin antagonist, methysergide. Vascular permeability at 4 h was not inhibited by pyrilamine or methysergide but was inhibited by a cyclooxygenase inhibitor, indomethacin, with a parallel decrease in the prostaglandin E2 level in the pouch fluid. These results suggest that the TPA-type tumor promoters induce inflammation by the mechanism of mast cell degranulation within a short period, this being followed by the stimulation of arachidonic acid metabolism. The mechanism of the in vivo effect of the TPA-type tumor promoters is discussed and compared with in vitro effects that we have previously reported.     

Neurogenic inflammation, vascular permeability, and mast cells

Electrical stimulation (ES) of sensory nerves causes increased vascular permeability and vasodilatation, a process known as neurogenic inflammation. The purpose of this study was to assess the role of mast cells in neurogenic inflammation induced by ES of sensory nerves. ES of the rat saphenous nerve for 1, 3, 5, 15, or 30 min induced a 166 to 436% increase in the amount of 125I-albumin deposited in the skin. Through the initial 15 min of ES, the histamine content of the skin remained unchanged. However, 30 min of ES caused a 22.1% decrease in skin histamine (p less than 0.05). ES for 5 min followed by measurement of vascular permeability from 0 to 30 min thereafter resulted in maximal increases in 125I-albumin in the skin immediately after cessation of the pulse of ES. When skin histamine was measured at various intervals after a 5-min pulse of ES, no change in the histamine content was observed through the subsequent 30 min. When mast cell degranulation was assessed histologically, 5 min of ES failed to stimulate mast cell degranulation. However, 30 min of ES caused a significant increase in the proportion of degranulating mast cells. When draining venous plasma histamine was monitored before, during and after ES, no change in plasma histamine was observed. In contrast, the intradermal injection of 5 micrograms of compound 48/80 produced a significant increase in plasma histamine. In order to examine the possibility that histamine might be released but remain in the skin after ES, skin "blisters" were developed by intradermal injections of saline. There was a significant increase in the amount of 125I-albumin extravasated into blister fluid measured after 3, 5, and 10 min of ES and a significant increase in histamine after 5 or 10 min. Therefore, prolonged ES of sensory nerves can cause mast cell degranulation. However, ES causes increased vascular permeability at times when no mast cell activation can be observed. These data suggest that the initial phases of neurogenic inflammation are independent of mast cell activation.     

Angiostrongylus cantonensis: Biogenic amines in the lungs of infected rats

Levels of histamine, serotonin, norepinephrine, and dopamine were estimated sequentially in rats parasitized by the lungworm, Angiostrongylus cantonensis, between 30 and 75 days postinfection. The highest level of histamine in the infected lungs was 52.19 μg/g wet wt tissue, 13 times higher than the level found in control rats. The level of serotonin rose from the normal level of 6.41 to 10.27 μg/g wet wt tissue after the worms had lodged in the pulmonary artery for 15 days. There were no changes in norephinephrine or dopamine. Studies of host cell response to infection revealed that the increased histamine and serotonin levels corresponded to a rise in the lung population of mast cells, suggesting that these cells produced the amines.     

Acute experimental autoimmune encephalomyelitis in mice. I. Adjuvant action of Bordetella pertussis is due to vasoactive amine sensitization and increased vascular permeability of the central nervous system

Experimental autoimmune encephalomyelitis (EAE) in mice is dependent upon the use of Bordetella pertussis suspensions as an adjuvant. Intravenous administration of B. pertussis causes an increased vascular permeability in brain tissue and an increased vascular sensitivity to vasoactive amines which promotes the development of EAE. The efficacy of different batches and strains of B. pertussis in the expression of EAE closely correlates with the vasoactive amine sensitization activity of each material tested. Pertussigen, the histamine sensitizing factor (HSF), is responsible for these adjuvant properties whereas purified endotoxin is inactive. The effect of cimetidine, diphenhydramine, methysergide, reserpine, and cyproheptadine on B. pertussis induced histamine sensitivity and the expression of EAE are examined. Cyproheptadine, an agent with mixed histamine and serotonin blocking properties, blocks both B. pertussis-induced vasoactive amine sensitization and the expression of EAE.     

Effects of a Dictamnus dasycarpus T. extract on allergic models in mice

The anti-allergic effect of a 70% ethanol extract from Dictamnus dasycarpus Turcz (DDT) was studied in mice. DDT at doses of 200 and 500 mg/kg inhibited the systemic anaphylactic shock induced by compound 48/80 in a dose-dependent manner. It also inhibited dose-dependently the scratching behavior induced by compound 48/80, histamine and serotonin. An increase in the vascular permeability induced by compound 48/80, histamine and serotonin was also inhibited by DDT. In an in vitro study, DDT inhibited the histamine released from rat peritoneal mast cells induced by compound 48/80. It seems likely from these findings that DDT was effective in antagonizing certain pharmacological effects induced by compound 48/80 that occurred via both histamine and serotonin released from mast cells. In conclusion, DDT may be effective in the relief of symptoms of allergic atopic dermatitis and other allergy-related diseases.     

An extract of rat submandibular glands activates platelets and enhances cutaneous vascular permeability in rats and guinea pigs

Washed, [3H]serotonin-labeled platelets from rats and guinea pigs were stimulated in vitro with a novel protein extracted from rat submandibular salivary glands (RS-PAP) and with the phospholipid platelet- activating factor 1-0-alkyl-2-acetyl-sn-glycero-3-phosphorylcholine (AGEPC). Rat platelets, which are refractory to AGEPC stimulation, underwent shape-change, aggregation and secretion of [3H]serotonin in response to graded doses of RS-PAP and AGEPC. Intradermal injections of histamine, RS-PAP and AGEPC caused a dose-related increase in local microvascular permeability in rats, as measured by the extravasation of plasma containing Evans blue dye. Similarly, histamine, RS-PAP and AGEPC increased cutaneous vascular permeability when injected intradermally in guinea pigs. The vascular permeability induced by histamine and RS-PAP, but not by AGEPC, was partially inhibited by pretreatment with an antihistamine (diphenhydramine HCl). Pretreatment of guinea pigs with captopril, an inhibitor of angiotensin-converting enzyme (ACE), partially inhibited cutaneous responses to subsequent intradermal injections of histamine, RS-PAP and AGEPC. Regardless of pretreatment with diphenhydramine or captopril, skin test sites injected with large amounts of RS-PAP became hemorrhagic within minutes and necrotic within 12 hours.     

Acute and chronic surgical vagotomy (SV) and gastric mucosal vascular permeability in ethanol treated rats.

The role of vagus nerve was studied in the development of gastric mucosal damage induced by ethanol (ETOH). The investigations were carried out on Sprague-Dawley rats. The gastric mucosal damage was produced by i.g. administration of 1 ml 96% ETOH. Acute surgical vagotomy (ASV) was carried out 30 min, chronic surgical vagotomy (CSV) 14 days before the ETOH application. The animals were sacrificed at 0, 1, 5, 15, 60 min after ETOH. Evans blue (EB) (1 mg/100 g) was given i.v. 15 min before autopsy. The number and severity of lesions the EB accumulation of the gastric juice and gastric mucosa were noted. It was found, that: 1. The vascular permeability increased after ETOH treatment at an early state (within 1-5 min) in association to the macroscopic appearance of erosions. 2. The number and extension of lesions, the EB concentrations in gastric juice and gastric mucosa were significantly higher both after ASV and CSV. 3. Surgical vagotomy alone did not increase the vascular permeability. 4. No significant ulcer formation was observed in vagotomized rats without ETOH treatment. It was concluded, that 1. Both ASV and CSV enhanced the development of gastric mucosal injury induced by ethanol. 2. Neither acute nor chronic surgical vagotomy exerted an effect of the development of mucosal injury and vascular permeability without the application of the noxious agent. 3. The further increase of enhanced vascular permeability by vagotomy probably has an etiologic role in the aggravating effect of ASV and CSV on the development of chemical-induced lesions.     

The role of the leukocytes in increasing the vascular permeability in an infectious inflammation focus]

The model of acute infectious peritonitis in rats with vinblastine-induced leukopenia has been used to show that the leukocyte depletion significantly influences the vascular permeability of abdominal cavity during the whole period of exudation. It inhibits the vascular permeability rise both in the immediate phase and in the initial period of delayed phase (5 h). 12 hours-5 days after the inflammatory agent action the vascular permeability under conditions of primary leukopenia appears to be more than in the natural course of inflammation, that coincides with excess of the leukocyte number usual for the inflammatory focus and with its significant increase in blood. The results indicate the essential role of leukocytes both during the immediate and delayed phases of increase in the vascular permeability of inflammatory infectious focus.