The classification of prostaglandin DP‐receptors in platelets and vasculature using BW A868C, a novel, selective and potent competitive antagonist

Abstract

1 BW A868C, a novel compound, behaved as a simple competitive antagonist in a human washed platelet aggregation assay. Anti-aggregatory concentration-effect curves to BW 245C were displaced in a parallel manner. The shifts accorded with a Schild plot slope of unity and a pKB of 9.26. 2 Inhibition of platelet aggregation by prostaglandin D2 (PGD2) was antagonized with a similar potency, as were the relaxation effects of BW 245C and PGD2 in the rabbit jugular vein. BW A868C can, therefore, be classified as a DP-receptor antagonist.3 Actions of BW A868C at other prostaglandin receptors (IP, EP,, EP2, TP and FP) were excluded at concentrations up to 1,000 times higher than the DP-receptor affinity. 4 Analyses of BW 245C-and PGD2-mediated effects were complicated by additional agonist receptor interactions which were revealed by BW A868C. In rabbit jugular vein a resistant phase of agonism was detectable, indicating that both agonists exerted effects through another receptor (possibly EP2). Also, PGD2, in addition to its anti-aggregatory effect on platelets, demonstrated a pro-aggregatory action in the presence of BW A868C. 5 The contractile effects of PGD2 in guinea-pig tracheal strips were resistant to 10 tM BW A868C indicating that they were not mediated through DP-receptors. 6 To our knowledge this is the first account of a well-classified competitive antagonist at the DP-receptor. Its potency and selectivity make it an important new tool in prostanoid receptor classification and identification.

Prostaglandin DP receptors positively coupled to adenylyl cyclase in embryonic bovine tracheal (EBTr) cells: pharmacological characterization using agonists and antagonists

“…This phenomenon of increased e cacy of BW245C was also observed in HEK 293 cells expressing the recombinant human DP receptor (Boie et al, 1995) where it was attributed to a subpopulation of endogenous EP receptors. BW245C is known to have activity at EP 2 receptors (Giles et al, 1989;Matsugi et al, 1995). However, in our studies since PGE 1 , PGE 2 and a variety of their EP-receptor-analogues were weak stimulators of the cyclase response in the EBTr cells, the apparent higher intrinsic activity of BW245C appear not to be due to stimulation of EP receptors in this cell-line.…”

“…Our data agreed well with the published results for PGD 2 and ZK110841 in the EBTr cell line . Interestingly, whilst the potency ratio of BW245C and PGD 2 in the EBTr cell assay system was approximately two, the ratio observed in human platelets was close to 30 (Giles et al, 1989;. This probably re¯ected di erences in the e ciency and degree of receptor-e ector coupling and/or di erences in receptor reserves in the two systems.…”

Prostaglandin D2 DP1 receptor is beneficial in ischemic stroke and in acute exicitotoxicity in young and old mice

“…BW245C is a selective DP1 agonist with high binding affinity (Ki= 250 nM) toward mouse DP1 (Kiriyama et al 1997;Narumiya et al 1999); it has been shown to increase intracellular levels of cAMP and activate adenylyl cyclase (Ientile et al 1983). Earlier studies proposed that BW245C had nonspecific effects through EP2 and EP4 receptors (Giles et al 1989;Hamid-Bloomfield and Whittle 1989;Matsugi et al 1995;Rangachari et al 1995); however, these effects were reported to be species specific. Nevertheless, nonspecific effects of BW245C in neurological settings have not been reported in mice.…”

Hierarchy of eosinophil chemoattractants: role of p38 mitogen‐activated protein kinase

“…However, eosinophils also express the DP receptor [13], which is a second receptor for PGD 2 , and DPdeficient mice have reduced pulmonary responses to allergen [14]. The DP receptor mediates the inhibition of platelet aggregation and mediator release from neutrophils, and vasodilation [15,16], but the role of DP in eosinophil function and allergic disease is unclear.…”

“…However, eosinophils also express the DP receptor [13], which is a second receptor for PGD 2 , and DPdeficient mice have reduced pulmonary responses to allergen [14]. The DP receptor mediates the inhibition of platelet aggregation and mediator release from neutrophils, and vasodilation [15,16], but the role of DP in eosinophil function and allergic disease is unclear.The eicosanoid 5-oxo-6,8,11,14-eicosa-tetraenoic acid (5-oxo-ETE) arises from the 5-lipoxygenase pathway. It is finally formed from 5-hydroxy-ETE by a highly specific dehydrogenase expressed in several inflammatory cells [17][18][19], and oxidative stress is a major stimulus for its release [20].…”