leukotriene-e4 and pobilukast

Topics: Acetophenones; Animals; Asthma; Azoles; Bronchi; Chromones; Dicarboxylic Acids; Drug Evaluation; Drug Evaluation, Preclinical; Guinea Pigs; Haplorhini; Humans; Indazoles; Leukotriene E4; Receptors, Leukotriene; Receptors, Prostaglandin; SRS-A; Structure-Activity Relationship; Tetrazoles

The effect of prior inhalation of the sulfidopeptide leukotriene receptor antagonist, SK&F 104353 (963 +/- 43.7 micrograms; mean +/- SEM), on (LTC4)- and leukotriene E4 (LTE4)-induced bronchoconstriction has been studied in six subjects with asthma (six male subjects, aged 24 to 36 years). Inhalation challenges with either synthetic LTC4 or LTE4 were performed after prior inhalation of aerosolized SK&F 104353 or placebo in a double-blind, randomized fashion. Airway responsiveness to each agonist was determined by the cumulative dose of agonist required to induce a 35% fall in specific airway conductance (PD35) as determined by linear interpolation of the log dose-response curve. There was no change in baseline specific airway conductance after inhalation of either placebo or SK&F 104353. LTC4- and LTE4-induced bronchoconstrictions were significantly inhibited by aerosolized inhalation of SK&F 104353 30 minutes before challenge. The geometric mean (GM) PD35 of LTC4 on the open-therapy and placebo-therapy days was 0.043 nmol (range, 0.01 to 0.1 nmol) and 0.036 nmol (range, 0.01 to 0.1 nmol), respectively. On the treatment day with SK&F 104353, it was not possible to obtain a GM PD35 LTC4 up to a maximum concentration of 0.52 nmol LTC4 (p less than 0.01). The GM PD35 of LTE4 on the open-therapy and placebo-therapy days was 0.30 nmol (range, 0.13 to 0.76 nmol) and 0.39 nmol (range, 0.14 to 0.9 nmol), respectively. On the treatment day with SK&F 104353, it was not possible to obtain a GM PD35 LTE4 up to a maximum concentration of 5 nmol LTE4 (p less than 0.005). Thus, LTC4- and LTE4-induced bronchoconstrictions are both inhibited by SK&F 104353.

Topics: Administration, Inhalation; Adult; Asthma; Bronchoconstriction; Dicarboxylic Acids; Dose-Response Relationship, Drug; Humans; Leukotriene E4; Male; Receptors, Immunologic; Receptors, Leukotriene; SRS-A

Contractions of guinea-pig tracheal preparations to cysteinyl-leukotrienes (LTC(4), LTD(4) and LTE(4)) were characterized in organ baths, and cysteinyl-leukotriene metabolism was studied using radiolabelled agonists and RP-HPLC separation. In the presence of S-hexyl GSH (100 microM) the metabolism of [(3)H]-LTC(4) into [(3)H]-LTD(4) was inhibited and the LTC(4)-induced contractions were resistant to CysLT(1) receptor antagonism but inhibited by the dual CysLT(1)/CysLT(2) receptor antagonist BAY u9773 (0.3 - 3 microM) with a pA(2)-value of 6.8+/-0.2. In the presence of L-cysteine (5 mM), the metabolism of [(3)H]-LTD(4) into [(3)H]-LTE(4) was inhibited and the LTD(4)-induced contractions were inhibited by the CysLT(1) receptor antagonist ICI 198,615 (1 - 10 nM) with a pA(2)-value of 9.3+/-0.2. However, at higher concentrations of ICI 198,615 (30 - 300 nM) a residual contraction to LTD(4) was unmasked, and this response was inhibited by BAY u9773 (1 - 3 microM). In the presence of the combination of S-hexyl GSH with L-cysteine, the LTD(4)-induced contractions displayed the characteristics of the LTC(4) contractile responses, i.e. resistant to CysLT(1) receptor antagonism, increased maximal contractions and slower time-course. This qualitative change of the LTD(4)-induced contraction was also observed in the presence of S-decyl GSH (100 microM), GSH (10 mM) and GSSG (10 mM). S-hexyl GSH, S-decyl GSH, GSH and GSSG all stimulated a formation of [(3)H]-LTC(4) from [(3)H]-LTD(4). In conclusion, GSH and GSH-related compounds changed the pharmacology of the LTD(4)-induced contractions by stimulating the conversion of LTD(4) into LTC(4). Moreover, the results indicate that, in addition to the metabolism of LTC(4) into LTD(4) and LTE(4), also the formation of LTC(4) from LTD(4) may regulate cysteinyl-leukotriene function.

Topics: Animals; Borates; Cysteine; Dicarboxylic Acids; Dose-Response Relationship, Drug; Glutathione; Guinea Pigs; In Vitro Techniques; Indazoles; Leukotriene Antagonists; Leukotriene C4; Leukotriene D4; Leukotriene E4; Leukotrienes; Male; Membrane Proteins; Muscle Contraction; Propionates; Quinolines; Receptors, Leukotriene; Serine; SRS-A; Trachea

We report the characterization of two distinct binding sites with receptor characteristics for leukotriene (LT)D4 and LTC4 in membranes from human lung parenchyma. The use of S-decyl-glutathione allowed us to characterize a previously unidentified high affinity binding site for LTC4. Computerized analysis of binding data revealed that each leukotriene interacts with two distinct classes of binding sites (Kd = 0.015 and 105 nM for LTC4 and 0.023 and 230 nM for LTD4) and that despite cross-reactivity, the two high affinity sites are different entities. LTD4 binding sites displayed features of G protein-coupled receptors, whereas LTC4 binding sites did not show any significant modulation by guanosine-5'-(beta, gamma-imido)triphosphate or stimulation of GTPase activity. The antagonists ICI 198,615 and SKF 104353 were unselective for the high and low affinity states of LTD4 receptor, whereas only SKF 104353 was able to recognize the two [3H]LTC4 binding sites although with different affinities. These data indicate that in human lung parenchyma, LTD4 and LTC4 recognize two different binding sites; these binding sites are different entities; and for LTD4, the two binding sites represent the interconvertible affinity states of a G protein-coupled receptor, whereas for LTC4, the high affinity site is likely to be a specific LTC4 receptor.

Topics: Binding Sites; Dicarboxylic Acids; GTP Phosphohydrolases; Humans; Indazoles; Leukotriene Antagonists; Leukotriene C4; Leukotriene D4; Lung; Membrane Proteins; Receptors, Leukotriene; Tritium

Leukotrienes (LT) are potent spasmogenic agents in human isolated bronchial and pulmonary venous muscle preparations. Treatment of human isolated pulmonary veins with the L-serine borate complex (45 mM; 30 min) did not alter the LTC4 pD2 values in these preparations. The cysteinyl LT antagonists, ICI 198615, MK 571 and SKF 104353, significantly shifted to the right the LT concentration-effect curves in airways with pKB values against LTC4 of 8.4 for ICI 198615, 8.6 for MK 571 and 8.0 for SKF 104353. Similar results were found against LTD4. In contrast, these antagonists did not inhibit the LTC4 and LTD4 contractions in human pulmonary veins. LTE4 was a partial agonist on the human pulmonary veins and blocked the contractions with a pKp value of 6.3 against LTD4 and 6.6 against LTC4. An LT analog, BAY u9773, also blocked the LT contractions in bronchial and venous muscle preparations with pKp values against LTD4 and LTC4 of 6.5 and 6.7, respectively. These data provide pharmacological evidence for a second cysteinyl LT receptor in the human lung. One LT receptor (LT-1) is stimulated by all cysteinyl LT, found on airways and inhibited by the LT-1 antagonists, and a second receptor (LT-2) can also be stimulated by all cysteinyl LT and is found on pulmonary veins, resistant to LT-1 antagonists but blocked by LTE4 and the dual LT-1/LT-2 antagonist BAY u9773.

Topics: Adult; Aged; Cysteine; Dicarboxylic Acids; Female; Humans; Leukotriene E4; Lung; Male; Middle Aged; Models, Biological; Muscle Contraction; Propionates; Pulmonary Veins; Quinolines; Receptors, Immunologic; Receptors, Leukotriene; Receptors, Leukotriene B4; SRS-A

Serosal but not mucosal addition of the peptidoleukotrienes, leukotriene (LT) C4 (LTC4), LTD4 and LTE4 transiently (maximal response within 2 min) increased short-circuit current (Isc) and transepithelial conductance across stripped rabbit colonic mucosa mounted in Ussing chambers. All three peptidoleukotrienes elicited their responses in the presence of amiloride (10 microM) and were inhibited by serosal addition of the NaCl cotransport inhibitors bumetanide (100 microM) and furosemide (1 mM). The effects of the peptidoleukotrienes on Isc and transepithelial conductance were concentration-dependent with maximal effects occurring at 10 microM. Half-maximal effects were produced at 30 nM for LTC4, 50 nM for LTD4 and 450 nM for LTE4. The secretory responses to both LTD4 and LTE4 were antagonized in a concentration-dependent manner by the LTD4/LTE4 receptor antagonist, SK&F 104353 (2(S)-hydroxy-3-(R)-[(2-carboxyethyl)thio]-3-[2-(8 phenyloctyl)phenyl]propanoic acid). Complete inhibition of the LTD4 and LTE4 effects were observed at 0.1 microM SK&F 104353 and half-maximal effects were achieved at 0.6 nM SK&F 104353. At 10 microM SK&F 104353 only 50% inhibition of the LTC4-induced increase in Isc was observed. These results suggest the peptidoleukotrienes stimulate colonic Cl- secretion by receptor-mediated mechanisms and that receptors for LTC4 are distinct from those mediating the action of LTD4/LTE4.

Topics: Animals; Chlorides; Chromatography, High Pressure Liquid; Colon; Culture Techniques; Dicarboxylic Acids; Electric Stimulation; Intestinal Mucosa; Leukotriene E4; Rabbits; SRS-A

Leukotriene (LT) receptors in the guinea-pig ileum were characterized using LTB4, LTC4, LTD4 and LTE4 and the LT antagonists FPL 55712, ICI 198615 and (+/-)SKF 104353. LTB4 was inactive but the other LTs induced concentration-related contractions. LTC4 responses differed to those induced by LTD4 or LTE4. Inhibitors of LT metabolism had no significant effects on any LT responses. LTD4 contractions were inhibited by all three antagonists but a resistant response was apparent at concentrations of ICI 198615 greater than 10(-8) M. All three antagonists were weak/inactive against LTC4. LTE4 was a partial agonist which antagonized LTD4 responses but had little or no activity against LTC4 or histamine. These results suggest that two distinct LT receptor types exist on guinea-pig ileum. One type is predominantly activated by LTD4 and is antagonized by three structurally distinct LT antagonists and the partial agonist LTE4. The second type is predominantly activated by LTC4 and is insensitive to the LT antagonists.

Topics: Animals; Borates; Chromones; Cyclooxygenase Inhibitors; Cysteine; Dicarboxylic Acids; Guinea Pigs; Ileum; In Vitro Techniques; Indazoles; Indomethacin; Leukotriene E4; Male; Receptors, Immunologic; Receptors, Leukotriene; Serine; SRS-A; Stereoisomerism

The purpose of these experiments was to investigate the effects of the selective peptidoleukotriene receptor antagonist, SK&F 104353, on leukotriene (LT)C4, LTD4 and LTE4 vasopressor responses in conscious, normotensive rats. Steady-state plasma concentrations of SK&F 104353 at infusion rates of 0.2 mg/kg + 1 mg/kg/hr, 1 mg/kg + 3 mg/kg/hr or 2 mg/kg + 10 mg/kg/hr were 0.5, 1.6 and 9.4 micrograms/ml, respectively, indicating that the plasma concentrations of SK&F 104353 were related directly to the infusion rate. LTC4, LTD4 and LTE4 (0.17-170 nmol/kg i.v.) produced dose-dependent increases in mean blood pressure. The ED20 dose (i.e., dose required to increase blood pressure 20 mm Hg) of LTC4, LTD4 or LTE4 was 2.7 +/- 0.4, 2.2 +/- 0.3 and 109 +/- 17 nmol/kg, respectively. SK&F 104353 produced dose-dependent, parallel shifts to the right in the LTC4 dose-response curve. Administration of SK&F 104353 at doses of 0.2 mg/kg + 1 mg/kg/hr, 1 mg/kg + 3 mg/kg/hr or 2 mg/kg + 10 mg/kg/hr produced dose ratios (i.e., ratio of ED20 in presence of SK&F 104353 to that of the vehicle group) of 6, 12 and 26, respectively. Against LTD4 responses, SK&F 104353 at doses of 0.1 mg/kg + 0.3 mg/kg/hr or 0.2 mg/kg + 1 mg/kg/hr produced dose ratios of 3 and 9, respectively. At a dose of 1 mg/kg + 3 mg/kg/hr, there was no further increase in the dose ratio, whereas a dose of 2 mg/kg + 10 mg/kg/hr resulted in a dose ratio of greater than 100.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Blood Pressure; Dicarboxylic Acids; Leukotriene E4; Male; Prazosin; Rats; Rats, Inbred Strains; Receptors, Immunologic; Receptors, Leukotriene; SRS-A; Vasoconstriction; Vasoconstrictor Agents

Effects of the peptidoleukotriene receptor antagonist, SK&F 104353, were examined in vitro using stripped rat ileal mucosa in Ussing chambers. Changes in short-circuit current (Isc), transepithelial conductance (G1) and unidirectional and net Na+ and Cl fluxes measured in the absence or presence of SK&F 104353 (1 microM) revealed that serosal addition produced a decrease in net Na+ absorption and serosal-to-mucosal Cl- flux. Serosal addition of leukotriene (LT)D4 (10 muM) or LTE4 (10 microM) elicited transient increases in Isc and sustained decreases in G1 which were antagonized by serosal addition of SK&F 104353 in a concentration-dependent manner. Mucosal addition of SK&F 104353 (1 microM) also reduced the increase in Isc elicited by LTD4 (10 microM). LTD4 (10 microM) decreased unidirectional and net Na+ and Cl- fluxes along with G1 in the steady state. All of these changes were abolished by pretreatment with SK&F 104353 (1 microM). The intestinal secretagogues prostaglandin F2 alpha, histamine, serotonin, substance P and the thromboxane mimic, U46619, produced changes in Isc qualitatively similar to those of LTD4. However, the transient increase in Isc produced by these secretagogues was not antagonized by SK&F 104353 (1 microM). Additionally, lysbradykinin- and prostaglandin E1-induced increases in Isc were not antagonized by SK&F 104353 (1 microM). Stimulation with histamine (10 microM) or pretreatment with LTB4 (5 microM) did not alter the increase in Isc or decrease in Gt produced by the subsequent addition of LTD4 (10 microM). Pretreatment of the tissues with mepyramine (10 microM) also did not reduce the increase in Isc elicited by LTD4 (10 microM), although it inhibited completely the increase in Isc produced by histamine (10 microM).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Biological Transport; Dicarboxylic Acids; Electrolytes; Ileum; In Vitro Techniques; Intestinal Mucosa; Leukotriene E4; Male; Rats; Rats, Inbred Strains; SRS-A

SKF 104353 (2(S)-hydroxyl-3(R)-carboxyethylthio)-3-[2-(8-phenyloctyl) phenyl] propanoic acid) is a synthetic structural analog of leukotrienes D4 and E4 (LTD4, LTE4). This compound binds to guinea pig and human lung LTD4 receptors with affinities (Ki) of 5 +/- 2 and 10 +/- 3 nM, respectively. The Ki values of a reference compound, FPL 55712, were 2200 and 4500 nM, respectively, approximately 400- and 500-fold less effective than SKF 104353. LTD4- and LTE4-induced biosynthesis of thromboxane B2 has been shown to be mediated by LTD4 receptors in guinea pig lung in vitro. SKF 104353 did not induce synthesis of TxB2 in this system at concentrations of 1-20 microM. When SKF 104353 and increasing concentrations of LTD4 were incubated with guinea pig lung, the dose response curve of LTD4-induced TxB2 biosynthesis was shifted to the right with a -log[KB] = 8.4 +/- 0.2. LTD4-induced phosphatidylinositol (PI) hydrolysis in guinea pig lung has been shown to be the major signal transduction mechanism. In this system, SKF 104353 (1-20 microM) did not promote PI hydrolysis. Pretreatment of the [3H]myo-inositol-labeled guinea pig lung with SKF 104353 shifted the LTD4-induced PI hydrolysis dose response curve to the right, indicating that SKF 104353 inhibited LTD4 receptor-mediated intracellular second messenger formation. These results demonstrate that SKF 104353 is a high affinity, specific LTD4 receptor antagonist. It inhibited LTD4-induced PI hydrolysis and TxB2 biosynthesis in guinea pig lung. SKF 104353 may prove to be an important research tool for research on the activities of leukotrienes and of value therapeutically in the treatment of leukotriene-mediated diseases.

Topics: Animals; Binding, Competitive; Cell Membrane; Dicarboxylic Acids; Guinea Pigs; Humans; Leukotriene E4; Lung; Phosphatidylinositols; Receptors, Leukotriene; Receptors, Prostaglandin; SRS-A; Thromboxane B2; Type C Phospholipases