These end products activate cell signaling pathways, including mitogen activated protein kinase pathways. Activation of the MAPK pathway results in inflammation, mucus hypersecretion and airway hyperreactivity. MAPK signaling pathways are important in many cell processes including differentiation, proliferation, activation, degranulation, and migration. Three MAPK subfamilies have been well characterized: ERK, JNK, and p38. The extracellular signalregulated kinase pathway is usually activated by mitogens and growth factors while p38 and c-Jun NH2 terminal kinase pathways are associated with chronic inflammation and are typically activated by inflammatory cytokines, heat shock, and cellular stress. Activation of MAPK signaling induces inflammatory cytokine and chemokine production in airway epithelial cells, inflammatory cells, and airway smooth muscle cells. Humans with severe asthma have increased activated p38 in airway epithelium compared to mild asthmatics or healthy controls, as demonstrated by increased immunostaining of phosphorylated p38 in airway biopsies. Inhibition of MAPKs is protective in allergen challenge models of asthma. Inhibition of p38, either pharmacologically or with antisense oligonucleotides, partially prevents airway hyperreactivity after sensitization and challenge in mice. Eosinophil influx into bronchoalveolar lavage is the dominant event in antigen challenged animals, and is prevented by a p38 inhibitor in guinea pigs and mice. Blocking p38 also prevents IL-13 Cyprodime hydrochloride induced mucus metaplasia in human and mouse airway epithelial cells. Less is known about the role of the MAP kinases in ozoneinduced hyperreactivity. Inhibiting p38 prevents ozone-induced airway hyperreactivity in mice while inhibiting JNK is partially protective. Ozone-induced increases in inflammatory cells in bronchoalveolar lavage are significantly inhibited in Jnk1 knockout mice. The experiments described here use three different MAPK inhibitors to test whether dual inhibition of both p38 and JNK MAPK pathways prevents ozone-induced inflammation and subsequent airway hyperreactivity in guinea pigs. Ozone significantly potentiated bronchoconstriction in response to electrical stimulation of the vagus nerves compared to airexposed controls as previously reported. Treatment with any of the dual MAPK inhibitors prevented ozone induced airway hyperreactivity. Vehicle treatment had no effect on vagally mediated bronchoconstriction in either air or ozone exposed animals. M2 muscarinic receptors were dysfunctional in ozone treated animals as gallamine, an M2 selective inhibitor, potentiated bronchoconstriction in response to vagal stimulation in air-exposed animals but not in ozone-exposed animals ; an effect that is consistent with BRACO 19 trihydrochloride decreased function of neuronal M2 muscarinic receptors. Ozone induced M2 receptor dysfunction was prevented by treatment with V-05-014 and V-05-015, and attenuated by treatment withV-05-013.