pf-04418948 and butaprost

Prostaglandin E2 (PGE2) is a regulator of gastrointestinal motility that might be involved in impaired motor function associated to gut inflammation. The aim of the present work is to pharmacologically characterize responses to exogenous and endogenous PGE2 in the mouse colon targeting EP2 and EP4 receptors.. Wild type (WT) and EP2 receptor knockout (EP2-KO) mice were used to characterize PGE2 and butaprost (EP2 receptor agonist) effects on smooth muscle resting membrane potential and myogenic contractility in circularly oriented colonic preparations.. In WT animals, PGE2 and butaprost concentration-dependently inhibited spontaneous contractions and hyperpolarized smooth muscle cells. Combination of both EP2 (PF-04418948 0.1μM) and EP4 receptor antagonists (L-161,982 10μM) was needed to block both electrical and mechanical PGE2 responses. Butaprost inhibitory responses (both electrical and mechanical) were totally abolished by PF-04418948 0.1μM. In EP2-KO mice, PGE2 (but not butaprost) concentration-dependently inhibited spontaneous contractions and hyperpolarized smooth muscle cells. In EP2-KO mice, PGE2 inhibition of spontaneous contractility and hyperpolarization was fully antagonized by L-161,982 10μM. In WT animals, EP2 and EP4 receptor antagonists caused a smooth muscle depolarization and an increase in spontaneous mechanical activity.. PGE2 responses in murine circular colonic layer are mediated by post-junctional EP2 and EP4 receptors. PF-04418948 and L-161,982 are selective EP2 and EP4 receptor antagonists that inhibit PGE2 responses. These antagonists might be useful pharmacological tools to limit prostaglandin effects associated to dismotility in gut inflammatory processes.

Topics: Alprostadil; Animals; Azetidines; Colon; Dinoprostone; Female; In Vitro Techniques; Male; Mice, Knockout; Muscle Contraction; Muscle, Smooth; Receptors, Prostaglandin E, EP2 Subtype; Receptors, Prostaglandin E, EP4 Subtype; Thiophenes; Triazoles

Studies of the role of the prostaglandin EP(2) receptor) have been limited by the availability of potent and selective antagonist tools. Here we describe the in vitro/in vivo pharmacological characterization of a novel EP(2) receptor antagonist, PF-04418948 (1-(4-fluorobenzoyl)-3-{[(6-methoxy-2-naphthyl)oxy]methyl} azetidine-3-carboxylic acid).. Functional antagonist potency was assessed in cell-based systems expressing human EP(2) receptors and native tissue preparations from human, dog and mouse. The selectivity of PF-04418948 was assessed against related receptors and a panel of GPCRs, ion channels and enzymes. The ability of PF-04418948 to pharmacologically block EP(2) receptor function in vivo was tested in rats.. PF-04418948 inhibited prostaglandin E(2)(PGE(2))-induced increase in cAMP in cells expressing EP(2) receptors with a functional K(B) value of 1.8 nM. In human myometrium, PF-04418948 produced a parallel, rightward shift of the butaprost-induced inhibition of the contractions induced by electrical field stimulation with an apparent K(B) of 5.4 nM. In dog bronchiole and mouse trachea, PF-04418948 produced parallel rightward shifts of the PGE(2)-induced relaxation curve with a K(B) of 2.5 nM and an apparent K(B) of 1.3 nM respectively. Reversal of the PGE(2)-induced relaxation in the mouse trachea by PF-04418948 produced an IC(50) value of 2.7 nM. Given orally, PF-04418948 attenuated the butaprost-induced cutaneous blood flow response in rats. PF-04418948 was selective for EP(2) receptors over homologous and unrelated receptors, enzymes and channels.. PF-04418948 is an orally active, potent and selective surmountable EP(2) receptor antagonist that should aid further elaboration of EP(2) receptor function.

Topics: Alprostadil; Animals; Azetidines; Bronchioles; Carboxylic Acids; CHO Cells; Cricetinae; Cyclic AMP; Dinoprostone; Dogs; Female; Humans; In Vitro Techniques; Male; Mice; Mice, Inbred C57BL; Muscle Contraction; Myometrium; Rats; Rats, Sprague-Dawley; Receptors, Prostaglandin E, EP2 Subtype; Regional Blood Flow; Skin; Trachea