Leukotriene-induced Contraction Research Articles

Gossypol: a potent inhibitor of PAF-acether- and leukotriene-induced contractions of guinea-pig lung parenchyma strips.

Gossypol, a substance extracted from cotton plants, markedly inhibited the contractile responses of guinea-pig lung parenchyma strips stimulated with leukotriene B4 (LTB4), leukotriene D4 (LTD4) and PAF-acether but not the responses to histamine (except at high concentration). It was slightly less potent than nordihydroguaiaretic acid (NDGA) and a PAF-antagonist (BN 52021). From previously reported effects of gossypol on the cyclooxygenase and lipoxygenases, and on the similarity of the inhibition produced by NDGA and gossypol on the lung parenchyma, it is suggested that the inhibition of the myotropic activity of the lung parenchyma by gossypol is due to interactions with the formation of cyclooxygenase products within the guinea-pig lung.

Leukotriene-induced contraction is mediated by cysteinyl leukotriene receptor CysLT1 in guinea pig fundus but by CysLT1 and CysLT2 in antrum

Aims Leukotriene D 4 (LTD 4) causes contraction of the stomach through unclear receptors. The aim of the present study is to characterize the cysteinyl leukotriene receptor (CysLT) mediating leukotriene-induced muscle contraction in the stomach. Main methods We measured contraction of gastric muscle strips isolated from the guinea pig fundus and antrum caused by cysteinyl leukotrienes, including LTC 4, LTD 4 and LTE 4, as well as the dihydroxy leukotriene LTB 4 in vitro. Key findings In both fundic and antral muscle strips, LTC 4 and LTD 4 caused marked whereas LTE 4 caused moderate, concentration-dependent contractions. In contrast, LTB 4 caused only small contraction. The relative potencies for cysteinyl leukotrienes to cause contraction in both fundus and antrum were LTC 4 = LTD 4 > LTE 4. The LTD 4-induced contraction was not affected by tetrodotoxin or atropine, suggesting that the action is not neurally mediated. The LTD 4-induced contraction in the fundus was almost abolished by the CysLT 1 selective antagonist montelukast. In contrast, the LTD 4-induced contraction in the antrum was only partially inhibited by montelukast or the dual CysLT 1 and CysLT 2 antagonist BAY u9773. This antral contraction was almost abolished by the combination of montelukast and BAY u9773, indicating enhancement of inhibition. Significance The results of the present study demonstrate that cysteinyl leukotrienes LTC 4, LTD 4 and LTE 4 cause moderate to marked whereas the dihydroxy leukotriene LTB 4 causes small muscle contraction in the stomach in vitro. The leukotriene-induced contraction is mediated by CysLT 1 in fundus but by CysLT 1 and CysLT 2 in antrum.

Evaluation of Cysteinyl Leukotriene-Induced Contraction of Human Cultured Bronchial Smooth Muscle Cells

Background: Cysteinyl leukotrienes (cysLTs) are major mediators involved in bronchial asthma, particularly bronchial constriction. However, a contractile response of human bronchial smooth muscle cells (hBSMCs) to cysLTs has not been well characterized at cellular level. Methods: A contraction assay using collagen gel embedded with cultured hBSMCs was established to analyze contractile responses at cellular level. Contractile responses to several constrictors including cysLTs were evaluated in 6-day cultured gels with varying fetal bovine serum (FBS) concentrations. Results: Removal of FBS from the culture for the designated time periods resulted in increased contractile responses. CysLT-induced contraction of the gel became more pronounced and reproducible. CysLT₁R expression on the hBSMCs was significantly increased by the removal of FBS. Conclusion: Contractile responses of hBSMCs to cysLTs can be evaluated at cellular level for the first time. This experimental system may be useful for the in vitro evaluation and future development of cysLTs antagonists.

Prostacyclin modulation of contractions of the human pulmonary artery by cysteinyl–leukotrienes

The contractile response to cysteinyl–leukotrienes was studied in isolated human pulmonary arterial rings. Concentration–response curves for leukotriene C 4 were significantly potentiated by the cyclooxygenase inhibitor indomethacin (1.7 μM) and after endothelial denudation. Measurements of 6-keto prostaglandin F 1α showed that cysteinyl–leukotrienes stimulated the release of prostacyclin. A single concentration (1 μM) of either leukotriene C 4 or leukotriene D 4 resulted in both contraction and relaxation. Indomethacin abolished the relaxant phase and enhanced the amplitude of the contraction, supporting that cysteinyl–leukotriene-induced contractions of the human pulmonary artery may be functionally antagonised by the release of prostacyclin. The contractions induced by leukotriene C 4 were resistant to the two cysteinyl–leukotriene receptor antagonists MK 571 ((3-(-2(7-chloro-2-quinolinyl)ethenyl)phenyl)((3-(dimethylamino-3-oxopropyl)thio)methyl)thio propanoic acid, 1 μM) and BAY u9773 (6( R)-(4′-carboxyphenylthio)-5( S)-hydroxy-7( E),9( E),11( Z)14( Z)-eicosatetrenoic acid, 3 μM), both in the absence and presence of indomethacin. These findings suggest a functional cysteinyl–leukotriene receptor in the human pulmonary artery with antagonist properties not previously described in human tissue.

Response of the Isolated Guinea Pig Bladder to Exogenous and Endogenous Leukotrienes

Noninfectious urinary bladder inflammation is a poorly understood phenomenon, and the participation of leukotrienes (LTs) in the pathogenesis of bladder inflammation is unclear. Leukotrienes are synthesized by the bladder, and exogenous LTs induce contraction of isolated bladder segments. LTD4 and LTC4 were more potent contractile agents than LTE4. Leukotriene-induced contractions were blocked by ICI 198,615 (10−6 M. and 10−7 M.) a specific LT receptor antagonist. In the presence of indomethacin (5 × 10−6 M.), bladder contraction in response to LTD4 was increased.Endogenous LT release was studied using an experimental model of cystitis. Antigen (ovalbumin 10−6 to 10−2 mg./ml.) challenge of bladder segments isolated from actively sensitized animals induced release of LT, prostaglandin D2 and histamine. A-64077 (Zileuton), a 5-lipoxygenase (5-LO) inhibitor, significantly reduced contraction of sensitized bladder tissue in response to antigen challenge in a concentration-dependent manner and abolished LT release.These data indicate that the guinea pig urinary bladder produces sulfidopeptide-LTs that can be released upon specific stimulation. Furthermore, LTs activate specific receptors promoting bladder contraction. Our findings suggest that specific 5-LO inhibitors or LT-receptor antagonists might be useful in treating or preventing bladder inflammation.

Characterization of leukotriene-induced contraction of the guinea-pig gallbladder in vitro.

Metabolites of arachidonic acid like prostaglandins have an established role in the pathogenesis of gallstone formation and cholecystitis, but any contribution by leukotrienes is less clear. Leukotrienes might contribute to the disease process by contracting the inflamed and (or) obstructed gallbladder, resulting in further inflammatory damage and biliary pain. To better define the role of leukotrienes, we assessed their effects on gallbladder contractility in vitro. Both leukotriene C4 (LTC4) and D4 (LTD4) had a concentration-dependent excitatory effect on guinea-pig gallbladder smooth muscle. The LTD4-receptor antagonist MK-571 (1 microM) competitively depressed the contractile response, to both LTD4 and LTC4. The source of calcium was defined using ryanodine to deplete intracellular calcium stores and nifedinine to block extracellular entry. Ryanodine (10 microM) antagonized gallbladder contraction at low concentrations of LTD4 (10(-10) and 10(-9) M). Nifedipine (1 microM) had a greater inhibitory effect on the contractile response at high concentrations of LTD4 (10(-8)-10(-6) M). LTD4-induced contractions were unaffected in tissues pretreated with the neural blocker tetrodotoxin or the muscarinic antagonist atropine. Thus, leukotrienes act directly on the gallbladder smooth muscle, causing contraction at concentrations found in models of cholecystitis, suggesting that these inflammatory mediators contribute to the symptoms and morbidity associated with gallbladder disease.

Leukotriene-induced contraction of isolated guinea pig gallbladder (GB) strips.

Gallstone disease is a significant health problem; an estimated 15 million adults are affected by this biliary tract disease in North America. Cholesterol gallstone formation is accompanied by impaired GB motility. A later stage is cholecystitis- an inflammatory event which may increase smooth muscle tone, resulting in pain1. In animal models of cholecystitis, significant increases in the levels of arachidonic acid metabolites in GB perfusates has been demonstrated2. These metabolites, comprised of prostanoids (PS) and leukotrienes (LT), have traditionally been associated with many inflammatory processes3. The role of PS in the etiology of cholecystitis and gallstone formation has been well defined. However, to date, little is known regarding the role assumed by the LT’s in these disease states.

The action and metabolism of peptide leukotrienes in the isolated bullfrog lung

Leukotrienes (LTs) have been shown to cause contraction of mammalian airway smooth muscle. In this study, LTC4, LTD4, and LTE4 were tested on isolated strips of bullfrog lung. LTC4, LTD4, and LTE4 (10(-7) to 3 x 10(-10) M) stimulated lung contraction. LTC4 was the most potent, with LTD4 and LTE4 being of equal but lower potency. The cyclooxygenase inhibitors, indomethacin and ibuprofen, had no effect on the strength of leukotriene-induced contraction. In addition, the effects of three mammalian LTD4 receptor antagonists, L-649,923, L-648,051, and LY171883 were tested. All three antagonists failed to block LTC4-simulated contraction, but were effective blockers of LTD4. LTE4-stimulated contractions were significantly blunted by all three antagonists, but the extent of blockade was less than for LTD4. Significant bioconversion of [3H]LTC4 to LTD4 and LTE4 occurred in minced lung preparations but not in lung strips. Peptide leukotrienes caused contraction in amphibian lung, though the order of potency differs from mammals. Like mammals, frogs appear to have two classes of leukotriene receptors, one for LTC4 and one for LTD4-LTE4. These results support the hypothesis that leukotriene receptors have been highly conserved through evolution, despite the fact that the nature of tissue responsiveness to leukotrienes has changed over evolutionary time.

Differential effects of epithelium removal on the responsiveness of guinea-pig tracheal smooth muscle to bronchoconstrictors.

1 The influence of the epithelium on contractions produced by the peptidoleukotrienes, 5-hydroxytryptamine (5-HT) and the thromboxane mimetic, U-44069, was examined in trachea from control and ovalbumin-sensitized guinea-pigs. 2 In control tissues removal of the epithelium produced an approximately 2 to 4 fold leftward shift in leukotriene C4 (LTC4) and LTD4 concentration-response curves, but no effect on LTE4-induced contractions. Similar results were obtained in preparations from ovalbumin-sensitized animals. 3 Responses produced by 5-HT or U-44069 were similar in the presence and absence of the epithelium in control guinea-pigs. 4 Indomethacin produced contrasting effects on leukotriene-induced contractions in control guinea-pigs: an increase in sensitivity to LTC4 in the presence but not absence of the epithelium, no effect on LTD4-induced contractions and a decrease in sensitivity to LTE4 in both epithelium-containing and epithelium-free preparations. 5 These results indicate that there is selectivity in the effects of epithelium removal on agonist-induced contractions of the guinea-pig trachea. This provides further evidence for the modulatory influence of the epithelium on the reactivity of mammalian airway smooth muscle and supports the postulated existence of an epithelium-derived inhibitory factor. The observation that in intact trachea indomethacin mimics the effects of epithelium removal on LTC4-induced responses, suggests the involvement of a prostanoid(s) in this phenomenon.

Inhibition of leukotriene-induced contraction of guinea pig trachea by 5-lipoxygenase inhibitors

The effects of the 5-lipoxygenase inhibitors nordihydroguiaretic acid (NDGA), 5,8,11,14-eicosatetraynoic acid (ETYA), 1-phenyl-3-pyrazolidone (phenidone) and BW-755c, on the contractile response to LTC 4 or LTD 4 were examined on the isolated guinea pig trachea. Responses to either LTC 4 or LTD 4 or LTD 4 were obtained on indomethacin treated tissues, in the presence of either L-serine-borate complex or L-cysteine, respectively, to exhibit metabolic conversion of the leukotrienes. NDGA (30 μM) and ETYA (100 μM) produced a selective competitive antagonism of LTD 4 - induced contractions, while phenidone antagonized both LTC 4- and LTD 4 - induced responses in a non-competitive manner. In contrast, BW-755c (30 μM) did not significantly antagonize LTC 4 or LTD 4 concentration-response curves. The results suggest that leukotriene antagonism may be produced by large concentrations of some 5-lipoxygenase inhibitors.

Substituted arylmethyl phenyl ethers. 1. A novel series of 5-lipoxygenase inhibitors and leukotriene antagonists

A series of new substituted arylmethyl phenyl ethers has been prepared. These compounds were tested as inhibitors of 5-lipoxygenase (5-LO) in rat neutrophils, in vitro antagonists of leukotriene-induced contraction of guinea pig (GP) lung parenchymal strips, and inhibitors of slow reacting substance of anaphylaxis (SRS-A) mediated bronchospasm in the GP in vivo. Most representatives of this new class of potential antiallergic/antiinflammatory agents showed potent inhibition of 5-LO activity in rat PMNs. The most potent compound, 2-[[3-(1-hydroxyhexyl)phenoxy]-methyl]quinoline (33), had an I50 of 0.12 microM in the rat PMN 5-LO assay and an I50 of 3.6 microM in the leukotriene-induced contraction of GP lung parenchymal strips, and it also showed 91% inhibition of SRS-A-mediated bronchospasm in the GP in vivo at 10 mg/kg, administered intraduodenally. Some of the compounds in this series were also leukotriene antagonists in vitro, and several of them showed in vivo activity against SRS-A-mediated bronchospasm in the GP.

Suppression by 5'-methylthioadenosine of histamine or leukotriene-induced contraction in isolated guinea pig tracheal rings.

5′-Methylthioadenosine (MTA) is a naturally occurring purine nucleoside, which is produced from S-adenosylmethionine by several biosynthetic routes (1) (2) and metabolized by MTA Phosphorylase to S-methylthioribose-1-phosphate and adenine.(3) MTA has been shown to have numerous effects on cell metabolism and function(2) and recent interest has focused extensively on its anti-proliferative action.(4)(5) Snyder et al(6) suggested that MTA stimulates the adenosine receptor. There are many reports that, in the human subjects, many cells including tracheal smooth muscle cells, have the adenosine receptor.(7) The action of adenosine on tracheal muscle cells in vitro has been intensively investigated(8), but there are no reports concerning the action of MTA on tracheal smooth muscle preparations.KeywordsAdenosine ReceptorTracheal RingTracheal Smooth MuscleTracheal Smooth Muscle CellTracheal ContractionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Suppression by metylthioadenosine of histamine or leukotriene-induced contraction in isolated guinea pig tracheal rings: 141

Methylthioadenosine(MTA) is a naturally occurring purine nucleoside which has been shown to have numerous effects on cell metabolism and function. We studied the action of MTA on tracheal smooth muscle, using isolated guinea pig tracheal rings. The tracheal rings were suspended in a 10 ml organ bath, containing atropinized Krebs-Henseleit solution. When MTA was added to the medium, relaxation of isolated guinea pig tracheal rings occurred after a latent period and was dose-dependent over concentrations ranging from 50 to 1000 μM. Pretreatment of the tracheal rings with 100 μM MTA inhibited the contraction produced by varying concentrations of histamine or leukotriene D4. The inhibition caused by 100 μM MTA was dependent on histamine or leukotriene D4 concentrations, ie 51% at 0.25 μg/ml histamine, 42.5% at 1.0 μg/ml histamine, 22% at 2.0 μg/ml histamine, and 81% at 0.5 μg LTD4, 50% at 1 μg LTD and 46.2% at 2 μg LTD4. The tracheal contractions induced by a standard concentration of histamine(1 μg/ml or leukotriene D4 (1 μg) were inhibited dose-dependently by pretreatment with MTA, ie 22% (histamine), 8.4%(leukotriene D4 at 10 μM, and 58%(histamine), 25%(leukotriene D4) at 100 μM. 500 μM of MTA blocked completely the contraction induced by histamine or leukotriene D4. It seems that MTA is an important modulator of tracheal smooth muscle cell function.

Mechanism of leukotriene-induced contraction of isolated guinea pig tracheal smooth muscle.

The mechanical response of guinea pig tracheal smooth muscle to leukotriene (LT) B4, C4, D4 and E4 was investigated, and the effects of several agents on LT-induced contraction were determined. Agents used in the present study were: verapamil, a Ca-channel blocker; dibutyryl cyclic-AMP (DBcAMP); aminophylline; N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride (W-7), a calmodulin antagonist; N-(6-aminohexyl)-1-naphthalene-sulfonamide hydrochloride (W-5), resembling W-7 in structure but without calmodulin antagonism. The results were as follows: 1) LTB4 had a contractile activity, dependent on the [Ca]o concentration; it was suppressed by a [Mg]o increase to 1.2 mM and over. Little effect was observed from other drugs. 2) Contractile activities of LTC4, D4 and E4 were dose-dependent, depending upon [Ca]o as well as LTB4. 3) Verapamil (5×10−6−10−3 M), DBcAMP (3×10−6−3×10−3 M) and aminophylline (3×10−8−3×10−3 M) suppressed LTs (C4, D4, and E4, 10−8 M)-induced contraction dose-dependently. However, W-7 and W-5 did not suppress LT-induced contraction. These results suggest that the LTC4-, D4-and E4-induced responses could be explained by the effect of LTC4, D4 and E4 on increasing Ca influx through the plasma membrane.

Prostacylin modulates the responses to leukotrienes C 4 and D 4 of guinea-pig airway smooth muscle

Superfusion of lung parenchymal strips or tracheal strips from the guinea-pig with effluent from perfused isolated lungs reduced the contractions elicited by leukotriene C 4 (LTC 4) and leukotriene D 4 (LTD 4) but not those elicited by acetycholine (ACh). Incubation of the lung perfusate for 15 min at 37°C removed the inhibitory effect, as did treatment of the lungs with indomethacin (0.5 μg ml −1) suggesting that a labile cyclo-oxygenase product was causing the inhibition. Addition of prostacylin (0.8–5.0 ng ml −1) to the fluid superfusing tracheal and parenchymal strips produced a dose-related decrease in leukotriene-induced contractions, whereas 6-oxo-PGF 1α and PGE 2 were inactive. Contractions of tracheal strips induced by LTC 4 were significantly enhanced by infusion of PGF 2α. Parenchymal strips usually developed tachyphylaxis to repeated doses of LTC 4. This tachyphylaxis has less evident in the presence of indomethacin (2 μg ml −1). Contractions of parenchymal and tracheal strips to histamine, acetylcholine and the stable thromboxane mimetic U-46619 were unaffected by infusion of prostacyclin (5 ng ml −1). These results indicate that prostacyclin selectively antagonises airway smooth muscle reactivity to LTC 4 and LTD 4 by a mechanism which remains to be elucidated.

Leukotriene-induced contraction and thromboxane production in guinea-pig lung parenchymal strips.

Addition of leukotrienes (LTs)C4 and D4 to guinea-pig isolated lung parenchymal strips stimulated the production of thromboxane A2(TxA2) and prostacyclin (PGI2) as determined by radioimmunoassay of their respective degradation products, thromboxane B2(TxB2) and 6-keto-prostaglandin F1 alpha (6-keto PGF1 alpha) in the bathing medium. However, contraction of the lung strips in response to LTD4 preceded the increases in the levels of these products in the organ bath. Pretreatment of the lung strips with aspirin, indomethacin or BW 755C abolished the formation of TxA2 and PGI2 but had no significant effect (10-25% inhibition) on LT-induced contraction. By contrast, a similar concentration of indomethacin significantly inhibited LTD4-induced contractions when the agonist was administered as a bolus to superfused lung strips. It is concluded that the production of metabolites of arachidonic acid in response to the leukotrienes is not a major mechanism mediating their contractile action in peripheral lung tissues at equilibrium, but its contribution to the contractile response may vary with experimental technique.

Stimulation of arachidonic acid metabolism and generation of thromboxane A2 by leukotrienes B4, C4 and D4 in guinea-pig lung in vitro.

1 Leukotriene C4 (LTC4), LTD4, slow-reacting substance of anaphylaxis (SRS-A) (from guinea-pig lung), bradykinin (Bk) and arachidonic acid (AA) release thromboxane A2 (TxA2) and prostaglandin-like materials from guinea-pig isolated perfused lungs. 2 Release of TxA2 induced by LTC4 and LTD4 is inhibited by a thromboxane synthetase inhibitor, imidazole (2.9 mM). 3 Mepacrine (200 microM), a phospholipase inhibitor, inhibits release of TxA2 and prostaglandin-like materials caused by SRS-A and Bk but not that due to exogenous AA 4 Leukotrienes B4, C4 and D4 are approximately equipotent in inducing dose-related contractions of guinea-pig parenchymal strips (GPPs). 5 Leukotriene-induced contractions of GPPs are greatly inhibited by imidazole (2.9 mM), carboxyheptylimidazole (24 microM) and mepacrine (400 microM). 6 FPL 55712 (1.9 microM), the SRS-A antagonist, blocks contractions of GPPs induced by LTC4 and LTD4 but not those due to LTB4 or Bk. 7 Tachyphylaxis to LTB4 occurs in GPPs but not to LTC4 or LTD4. 8 These results suggest that in guinea-pig lung in vitro, LTB4, LTC4 and LTD4 activate a phospholipase with subsequent generation of cyclo-oxygenase products of which TxA2 plays an important role.

Contractile events induced by LTD4 and histamine in smooth muscle--a function of Ca2+ utilization.

Contractile events induced by LTD4 and histamine in smooth muscle--a function of Ca2+ utilization.

The effects of salbutamol, theophylline and FPL55712 on leukotriene contraction of guinea pig trachea

Contraction of guinea pig tracheal smooth muscle was induced by leukotriene C 4 or leukotriene D 4. The inhibition of the smooth muscle contraction by salbutamol and theophylline was compared with the inhibition by FPL 55712. Salbutamol (5×10 −8−5×10 −7 M) significantly inhibited the leukotriene-induced contraction. The degree of inhibition was greater than thatobserved with FPL55712 (10 −6−10 −4 M). Theophylline (10 −6−10 −4 M) did not affect the leukotriene-induced contraction, but enhanced the effect of salbutamol when these agents were combined.

Effects of salbutamol (S), theophylline (T) and FPL 55712 (FPL) on leukotriene-induced contraction of guinea pig trachea in vitro

Effects of salbutamol (S), theophylline (T) and FPL 55712 (FPL) on leukotriene-induced contraction of guinea pig trachea in vitro