An alternative pathway for metabolism of leukotriene D₄: effects on contractions to cysteinyl‐leukotrienes in the guinea‐pig trachea

Abstract

1 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. 2 In the presence of S-hexyl GSH (100 mM) the metabolism of [ (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 mM). 4 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 mM), GSH (10 mM) and GSSG (10 mM). 5 S-hexyl GSH, S-decyl GSH, GSH and GSSG all stimulated a formation of [

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

“…This is in agreement with a previous study showing a difference in the antagonist sensitivity between LTC 4 and LTD 4 in gastric smooth muscle cells and suggests that both CysLT 1 and CysLT 2 might mediate leukotriene-induced contraction not only in the antrum but also in the fundus (DeLegge et al, 1993;Bäck et al, 2001).…”

“…Tetrodotoxin was obtained from Tocris Cookson, Avonmouth Bristol, UK. L-serine borate was prepared from L-serine and boric acid solutions and buffered at pH 7.4 with NaOH (Bäck et al, 2001).…”

“…1). In some contraction experiments with LTC 4 , the preparations were incubated for 30 min with L-serine borate, 45 mM, before beginning the experiments to inhibit the metabolism of LTC 4 into LTD 4 (Bäck et al, 2001). For studies using atropine and tetrodotoxin, the muscle strips were exposed to the indicated concentrations of these agents for 6 min and 15 min, respectively, and then to the various concentrations of leukotrienes (Chang et al, 2008;Goldenberg and Subers, 1983;Huang, 2009;von Schrenck et al, 1989).…”

Guinea pig cysteinyl leukotriene receptor 2 (gpCysLT2) mediates cell proliferation and intracellular calcium mobilization by LTC4 and LTD4

“…4C). Previous reports showed functional antagonism of Bay-u9773 to the contraction activities of CysLT2 in organ bath assay of guinea pig (18,19). We showed that Bay-u9773 behaved as an antagonist and a partial agonist for gpCysLT2 in intracellular calcium response as well as other species (23) and that Bay-u9773 induced cellular proliferation by itself and with the following stimulation of LTC4.…”

“…Based on functional smooth muscle studies, it was reported that gpCysLT2 was expressed in the ileum (18) and trachea (19). We investigated the tissue distribution of guinea pig CysLT2 gene by quantitative real time PCR (Fig.…”