Release Of Slow Reacting Substance Research Articles

Models for evaluating the anti-inflammatory effects of inhibitors of arachidonic acid metabolism.

Inhibitors of arachidonic acid metabolism were characterized by their ability to modulate slow reacting substance (SRS) and prostaglandin E2 (PGE2) release from stimulated mouse peritoneal macrophages in-vitro. Differential effects of cyclo-oxygenase (CO) and lipoxygenase (LO) enzyme inhibitors and compounds which inhibit both enzymes were demonstrated using several animal models of inflammation. Carrageenan-impregnated sponges implanted subcutaneously in rats and immune-complexes injected intraperitoneally in mice produced inflammatory responses characterized respectively by polymorphonuclear (PMN) cell infiltration and by increased vascular permeability. Dual CO/LO inhibitors (eg. BW 755c and timegadine) were capable of suppressing both parameters and reduced SRS and PGE2 formation in-vivo. In contrast, selective CO inhibitors (e.g. indomethacin, naproxen and R-830) were less active against permeability, and potentiated SRS release. Although selective CO inhibitors reduced PMN migration, this occurred at doses which exceeded those required for inhibition of PGE2. Compounds possessing LO inhibitory activity suppressed the cellular component of an Arthus type reaction in the rat pleural cavity, but were less active than selective CO inhibitors against carrageenan-induced paw oedema in rats.

Influence of Gymnema sylvestre on inflammation

The aqueous extract of Gymnema sylvestre leaves (GSE) tested on various inflammatory models showed anti-inflammatory activity by significantly inhibiting carrageenan-induced rat paw oedema and peritoneal ascites in mice. GSE elevated liver enzymes (e.g. γ-glutamyl transpeptidase (γ-GT) and Superoxide dismutase (SOD)) showing a protective mechanism against the release of slow-reacting substances and free radicals. GSE did not inhibit granuloma formation and related biochemical indices, such as hydroxyproline and collagen. GSE in high doses did not affect the integrity of the gastric mucosa and appears to be a less gastrotoxic anti-inflammatory agent when compared with other non-steroidal anti-inflammatory agents.

Inhibitory Effect of N-(3,4-Dimethoxycinnamoyl)anthranilic Ac d on Release of SRS from Alveolar Macrophages in Vitro

The effects of N-(3,4-dimethoxycinnamoyl)anthranilic acid (N-5') on the release of the slow-reacting substance (SRS) by zymosan- or Ca ionophore-stimulated rat and human alveolar macrophages (AM) were examined in vitro. Disodium cromoglycate (DSCG) was used as a control. N-5' at concentrations of 10−4—10−3 M significantly inhibited the release of SRS from both rat and human AM stimulated by zymosan. N-5' had almost the same inhibitory effect when added to the AM culture system at any time from 180 min before to 30 min after the addition of zymosan. N-5' (10−4-10−3 M) also significantly inhibited the release of SRS by Ca ionophore-stimulated rat AM. N-5' (10−6—10−3 M) had no significant effect on phagocytosis of yeast particles by rat AM DSCG (10“6—10−3 M) did not inhibit the release of SRS from the zymosan-stimulated rat AM. N-5' was concluded to have a relatively specific inhibitory effect on the non-immunological release of SRS from stimulated AM. It is postulated that N-5' inhibits the process of release of SRS from AM by acting after the initial stage.

Release of slow reacting substance from the guinea-pig lung by phospholipases A 2 of Vipera russelli snake venom

Phospholipases A 2 (PLA 2) of Vipera russelli venom were isolated by column chromatography. The ability of PLA 2 fractions to release slow reacting substance (SRS) was studied in the guinea-pig lung perfused with Krebs' solution. The relationship between the perfusion pressure change produced by PLA 2 and SRS release was also studied. Two PLA 2 fractions (II-5 and III-3; 3–100 μg), injected into the lung increased the perfusion pressure and released SRS. Pretreatment of the lung with indomethacin (10 μg) reduced the pressure response induced by the PLA 2 fractions. The SRS released in the lung effluent by PLA 2 was identified by bioassay as a mixture of thromboxane A 2 (TXA 2), prostacyclin (PGI 2) and leukotrienes. TXA 2 and PGI 2 release was also quantitated by radioimmunoassay of the degradation products TXB 2 and 6-keto-PGF 1 a , respectively. There was a positive linear correlation between the pressure increases and the ratios of TXB 2 to 6-keto-PGF 1 a ( r=0.87). It appears that the relative amounts of TXA 2 and PGI 2 released determine the effects of PLA 2 fractions on the guinea-pig lung. The release of arachidonic acid metabolites, prostaglandins and leukotrienes may account for part of the hypotensive action of PLA 2.

Inhibition of slow-reacting substance release by calmodulin blocker.

It was examined whether a calmodulin blocker could inhibit release of slow-reacting substance from human leukocytes. W-7, a specific calmodulin blocker, completely inhibited slow-reacting substance release induced by calcium ionophore or mite allergen at 5 X 10(-5) M, while W-12, which had a lower affinity to calmodulin, failed to inhibit the release even at 10(-4) M. It was suggested that calmodulin was involved in mechanisms of slow-reacting substance release. Release of PGE2 and PGF2 alpha by calcium ionophore was partially inhibited by 5 X 10(-5) M of W-7. The inhibitory effects of W-7 on slow-reacting substance release could be considered responsible for the suppression of phospholipase A2.

Release of slow reacting substance (SRS) from ocular tissues in the guinea pig

Ca ionophore A 23187 (A 23187) -or antigen-induced release of slow reacting substance (SRS) from passively sensitized ocular tissues or from ocular tissues of non-sensitized or actively sensitized guinea pigs was investigated. In non-sensitized guinea pigs, considerable amount of SRS was generated in choroid>conjunctiva>ciliary body, in this order, by A23187. However, the release from iris was negligible, and no release was observed in retina and cornea. In actively sensitized guinea pigs, similar results of the SRS release by specific antigen or A23187 were obtained from each ocular tissue in the same order as the A23187-non-sensitized tissue experiments. Furthermore, when choroid, ciliary body and iris tissue were sensitized passively by injecting antiserum of the guinea pig in vitereous humor and challenged by antigen, large amount of SRS was released from the choroid and ciliary body, less extent from the iris. The ileal contraction of guinea pig induced those SRS was almost completely inhibited by SRS-specific antagonist, FPL 55712. Although we failed to determine the types of leukotriene of the SRS released by chromatography because of very small amount of the tissue employed, it was suggested that SRS plays a role in inflammation or allergy of the uvea.

Studies on chemical mediator release from guinea pig lung fragments by Ca ionophore, A23187 (Π)

A Ca ionophore, A23187 has been thought to induce the chemical mediator release from a variety of cells by directly transporting Ca++ into the related cells. Our previous experiments on the release of histamine and slow reacting substance(SRS) from guinea pig lung fragments have suggested that A23187 activates cells prior to Ca++ influx for the release. In this report, we further examined the mode of action of A23187 in the release. The results obtained were as follows: 1) The release of histamine and SRS by A23187 was gradually increased with incubation time, reaching the maximum at 60 to 100min, as previously reported(whole stage). Under the same conditions without Ca++ & Mg++(lst stage), a small amount of both mediators was detected. 2) After 60min incubation at the 1st stage, an addition of Ca++(2nd stage) followed by 40min incubation induced the marked release of both mediators, but Mg++ did not lead to the release. The release by an addition of Ca++ at the 2nd stage was clearly different from that of the whole stage in terms of the very rapid and marked(1.5-fold in histamine & 2-fold in SRS at the whole stage) release. 3) An addition of bovine serum albumin which effectively binds with A23187, during the whole stage, caused surplus histamine and SRS release. 4) Both histamine and SRS release were dose-dependently inhibited by the treatment with diisopropyl-fluorophosphate. From the above results, it was further suggested that A23187 activates the cells prior to Ca++ influx.

Effect of benoxaprofen on release of slow-reacting substances from human lung tissue in vitro.

1. macroscopically normal human lung tissue was obtained from operative specimens removed for lung cancer and challenged with antigen or calcium ionophore. The release of histamine and slow-reacting substances was measured by fluorimetric and bioassay techniques respectively. 2. Benoxaprofen, a drug with inhibitory effects on the lipoxygenase and cyclo-oxygenase pathways, caused a dose-related reduction of release of slow-reacting substances without affecting histamine release. 3. These results with human lung tissue in vitro suggest that benoxaprofen may be used to investigate the role of slow-reacting substances in experimental and clinical asthma.

Release of a slow-reacting substance from rabbit platelets.

Washed rabbit platelets stimulated with platelet-activating factor, thrombin, or arachidonic acid, released a slow-reacting substance (SRS), whereas platelets aggregated by adenosine diphosphate did not. Production of platelet-derived SRS was neither affected by indomethacin nor aspirin but was reduced by large doses of eicosatetraynoic acid, an inhibitor of the cyclo-oxygenase and lipoxygenase. L-cysteine enhanced markedly the release of SRS from platelets. This SRS activity, which was antagonized by FPL 55712 and inactivated by arylsulfatase, followed the same elution pattern on Amberlite, silicic acid, and reverse phase high-pressure liquid chromatography columns as that described for the SRS from other origins. SRS activity released from platelets preincubated with [14C]arachidonic acid exhibited the same retention time as radioactivity in reverse phase high-pressure liquid chromatography. The release of a SRS from platelets is consistent with their implication in the pathogenesis of asthma and other lung diseases.

Effect of lipoxygenase inhibitors on release of slow-reacting substances from human lung

The effects of the lipoxygenase inhibitors nordihydroguaiaretic acid (NDG) and 3-amino-1-[m-(trifluoromethyl)-phenyl]-2-pyrazoline (BW 755C) on the release of slow-reacting substances (SRS) from human lung tissue were investigated in vitro. NDG (5 × 10 −6 M and 5 × 10 −5 M) and BW 755C (10 −5 and 10 −4 M) caused a dose-dependent inhibition of SRS release. There was a small reduction of histamine release with the higher concentration of each drug. These results suggest that lipoxygenase iny be useful in determining the role of SRS in inflammatory processes in vivo.

Release of leukotrienes C (LTC) and D (LTD) from inflammatory macrophages during phagocytosis of zymosan and bacteria.

Release of slow-reacting substance (SRS) was obtained from resident mouse peritoneal macrophages (R-M phi) upon stimulation with phagocytic stimuli (zymosan, bacteria). The release of SRS from thioglycollate elicited M phi was impaired, whereas that from BCG-elicited M phi was quantitatively unaffected. However, using a high pressure liquid chromatography separation procedure, qualitative variations between SRS released from R-M phi and BCG-M phi were observed. In both cases, LTC was the major component released from M phi, but greater amounts of LTD were released from BCG-M phi than from R-M phi. These data indicate that local environment alters leukotriene generation by M phi.

Release of slow-reacting substance of anaphylaxis from dispersed pig lung cells: effect of cyclo-oxygenase and lipoxygenase inhibitors

Study of the release of slow-reacting substance of anaphylaxis (SRS-A).from lung cells has been hampered by the lack of a suitable animal model. Using both immunologic and pharmacologic stimuli, we have obtained histamine and SRS-A release from dispersed pig lung cells containing 6% mast cells (with a histamine content of 1.9 pglcell). Lung cells dispersed from actively sensitized (with intratracheal Ascaris antigen) but not unsensitized pigs released both histamine (mean net release 33%) and SRS-A (mean release, 47 units/10 7 cells) when challenged with Ascaris antigen. Greater release of histamine (mean net release 52%) and of slow-reacting substance (SRS) (mean release 701 units/10 7 cells) was induced by challenge with the calcium ionophore A23187. The pharmacologic and physicochemical characteristics of the SRS together with its profile of enzymatic inactivation resembled those described for SRS-A released from human lung. Both antigen-induced and A23187-induced SRS(-A) release were enhanced by indomethacin, a cyclo-oxygenase inhibitor, but inhibited by both phenidone (IC 50 35 μM) and eicosatetraenoic acid (IC 50 15 μM), inhibitors of both cyclo-oxygenase and lipoxygenase, confirming that generation of SRS(-A) by either stimulus required an intact lipoxygenase pathway of arachidonic acid metabolism.

Phagocytosis stimulates the release of a slow reacting substance in cultured macrophages.

1 A slow-reacting substance (SRS) was released from non-elicited mouse peritoneal macrophages during phagocytosis of zymosan particles, whereas no detectable SRS was produced by resting cells. 2 The macrophage SRS induced a delayed and slow contraction of the guinea-pig ileum but not of the chick rectum. 3 The myotonic activity was antagonized by low concentrations of FPL 55712 (sodium 7-[3-(4-acetyl-3-hydroxy-2-propylphenoxy)-2-hydroxypropoxy]-4-oxo-8-propyl-4H-1 -benzopyran-2 carboxylate) but was not affected by mepyramine or hyoscine, and was not associated with tachyphylaxis. 4 SRS release was increased by indomethacin and was abolished by the lipoxygenase and cyclooxygenase inhibitor, BW755C (3-amino-1-[m-(trifluoromethyl)-phenyl]-2-pyrazoline). 5 Addition of exogenous arachidonic acid or cysteine enhanced SRS production.

SLOW REACTING SUBSTANCE (SRS) FROM HUMAN LEUKOCYTES : I. Release of SRS from Human Neutrophil Leukocytes by Calcium Ionophore A23187

SLOW REACTING SUBSTANCE (SRS) FROM HUMAN LEUKOCYTES : I. Release of SRS from Human Neutrophil Leukocytes by Calcium Ionophore A23187

Non-immunological release of slow-reacting substance from guinea-pig lungs.

1 During incubation with calcium ionophore A23187, sensitized and unsensitized guinea-pig chopped lung released a slow-reacting substance (SRS) and histamine. 2 SRS possessed many characteristics of slow-reacting substance of anaphylaxis (SRS-A). It was inactivated by arylsulphatase, antagonized by FPL55712 (1 microgram/ml) and more stable in alkali than acid. Furthermore, it behaved like SRS-A by stimulating archidonic acid metabolism in guinea-pig isolated perfused lungs. 3 Maximal ionophore generation of SRS in sensitized lung was greater than maximal anaphylactic generation of SRS-A but the release of histamine was not significantly different. Simultaneous challenge with antigen and ionophore produced more SRS-like or SRS-A-like activity than either stimulus alone. 4 These results have shown a non-immunological release from guinea-pig lung of SRS which was similar (or possibly identical) to SRS-A. It is suggested that in addition to mast cells, other cell types may be involved.

Release of Slow-Reacting Substance from Anaphylactic Lung Tissue and Its Modification by β-sympathomimetics

Anaphylactic release of slow-reacting substance of anaphylaxis (SRS-A) from chopped guinea pig lung was studied. The antibodies mediating the anaphylactic reaction were classified as IgG antibodies by PCA technique. Isoprenaline was found to inhibit the release of SRS-A in the concentration range 10-8-10-6M, while the beta2-selective agonist terbutaline showed inhibition in the concentration range 10-6-10-5M. The beta1-selective beta-agonist tazolol was ineffective when tested in the concentration range 10-7-10-5M. The rank order of inhibitory potency of the compounds on SRS-A release agree with that for histamine release.

Modulation of the Release of SRS-A from Bovine Lung <i>in vitr</i><i>o</i> by several Autonomic and Autacoid Agents

The immunological release of slow-reacting substance of anaphylaxis (SRS-A) from bovine lung is modulated by several autonomic and autacoid agents. Isoproterenol, a beta-adrenergic agonist, inhibited release of SRS-A, as did cyclic AMP. Phenylephrine also inhibited SRS-A release but through alpha-adrenergic mechanisms. This is in contrast to observations in human lung. Carbachol enhanced the release of bovine SRS-A. Histamine inhibited SRS-A release through the H2-receptor. Dopamine enhanced the release of SRS-A by means of a dopaminergic receptor. 5-HT did not significantly modulate SRS-A release.

The immunological release of slow-reacting substance of anaphylaxis from bovine lung.

Slow-reacting substance of anaphylaxis (SRS-A) was released immunologically from bovine lung in vitro. Polyphloretin phosphate inhibited release of SRS-A. Pretreatment of calves with aspirin potentiated SRS-A release on challenge. The partially purified SRS-A extract contracted the guinea-pig ileum and bovine pulmonary vein.

Ca++ dependence of histamine release and formation of slow reacting substance in the cat paw.

AbstractThe influence of divalent cations on the release of histamine and the formation of slow reacting substance (SRS) in the perfused cat paw induced by compound 48/80 was studied. Ca++ was found to have a stimulatory effect on both processes. Ca++ had no releasing effects per se. When the paws were perfused for 1 or 2 hrs with Ca++‐free salt solution, prior to compound 48/80, the release was depressed. Histamine release and formation of SRS were inhibited by disodium ethylene diamine tetraacetate (EDTA). In both instances the EDTA‐blockade could be reversed by Ca++, whereas Ca++, Mg++, Mn++ and Ni++ were ineffective substitutes. The EDTA‐blockade of histamine release but not that of the formation of SRS was also reversed by Sr++ and in some experiments by Ba++. The stimulatory effect of Sr++ on the release of histamine was weaker than that of Ca++. No significant stimulatory effect of Sr++ on the formation of SRS was observed. It is concluded that the release of histamine and the formation of SRS in the cat paw are Ca++‐dependent processes although in the case of histamine release Ca++ can partially be replaced by Sr++.

Inhibition of the release of slow-reacting substance of anaphylaxis in the rat with diethylcarbamazine.

SummaryThe immunologic release of SRS-Arat with intravenously administered antigen is described. Hetrazan effectively inhibits the antigen-induced release of SRS-Arat in a dose of 20 mg/kg iv. In this concentration, it has no influence on the bioassay system and does not prevent effective antibody-antigen interaction. Hetrazan does not produce an irreversible inhibition and must be present at the time of antibody-antigen interaction to effectively prevent the formation and release of SRS-Arat. Suppression of the 4-hour PCA reaction in the rat with Hetrazan plus mepyramine maleate and methysergide suggests that SRS-Arat may be a permeability factor involved in this reaction.