Melatonin MT₂ receptor is expressed and potentiates contraction in human airway smooth muscle

Nocturnal asthma is characterized by heightened bronchial reactivity at night, and plasma melatonin concentrations are higher in patients with nocturnal asthma symptoms. Numerous physiological effects of melatonin are mediated via its specific G protein-coupled receptors (GPCRs) named the MT 1 receptor, which couples to both G q and G i proteins, and the MT 2 receptor, which couples to G i . We investigated whether melatonin receptors are...