TRPA (and also TRPV1) receptors to augment the perception of pain. 12S-HpETE, which is the direct precursor to HxA3 and HxB3 in the ALOX12 pathway, may act only after being converted to these hepoxilins. The epoxide, 5,6-epoxy-8Z,11Z,14Z-eicosatrienoic acid (5,6-EET) made by the metabolism of arachidonic acid by any one of several cytochrome P450 enzymes (see Epoxyeicosatrienoic acid) likewise directly activates TRPA1 to amplify pain perception. Studies with mice, guinea pig, and human tissues and in guinea pigs indicate that another arachidonic acid metabolite, Prostaglandin E2, operates through its prostaglandin EP3 G protein coupled receptor to trigger cough responses. Its mechanism of action does not appear to involve direct binding to TRPA1 but rather the indirect activation and/or sensitization of TRPA1 as well as TRPV1 receptors. Genetic polymorphism in the EP3 receptor (rs11209716), has been associated with ACE inhibitor-induce cough in humans. More recently, a peptide toxin termed the wasabi receptor toxin from the Australian black rock scorpion (Urodacus manicatus) was discovered; it was shown to bind TRPA1 non-covalently in the same region as electrophiles and act as a gating modifier toxin for the receptor, stabilizing the channel in an open conformation. TRPA1 inhibition A number of small molecule inhibitors (antagonists) have been discovered which have been shown to block the function of TRPA1. At the cellular level, assays that measure agonist-activated inhibition of TRPA1-mediated calcium fluxes and electrophysiological assays have been used to characterize the potency, species specificity and mechanism of inhibition. While the earliest inhibitors, such as HC-030031, were lower potency (micromolar inhibition) and had limited TRPA1 specificity, the more recent discovery of highly potent inhibitors with low nanomolar inhibition constants, such as A-967079 and ALGX-2542 as well as high selectivity among other members the TRP superfamily and lack of interaction with other targets have provided valuable tool compounds and candidates for future drug development. Resolvin D1 (RvD1) and RvD2 (see resolvins) and maresin 1 are metabolites of the omega 3 fatty acid, docosahexaenoic acid. They are members of the specialized proresolving mediators (SPMs) class of metabolites that function to resolve diverse inflammatory reactions and diseases in animal models and, it is proposed, in humans. These SPMs also damp pain perception arising from various inflammation-based causes in animal models. The mechanism behind their pain-dampening effect involves the inhibition of TRPA1, probably (in at least certain cases) by an indirect effect wherein they activate another receptor located on neurons or