TRPV1 and gout: 126). In an additional animal model of MSU-induced gout, MSU injection increased tissue hydrogen peroxide levels, which stimulated TRPA1 and TRPV1 expression on sensory nerve endings, enhanced cellular infiltration and IL-1β levels, produced pain sensation and resulted in joint swelling. Both pharmacological inhibition and gene knockout of TRPA1 channels abrogated pain and oedema induced by MSU in animal models (Refs 127, 128, 129).