The neuronal M2 muscarinic receptor is a G protein-coupled receptor expressed in parasympathetic nerves that provides negative feedback for acetylcholine release. Dysfunction of neuronal M2 receptors is a mechanism for airway hyperreactivity in a variety of animal models of asthma. However, the poor specificity of available anti-M2 receptor antibodies makes quantifying M2 muscarinic receptors by immunostaining difficult, leaving unclear whether the diminished function of neuronal M2 muscarinic receptors is due to decreased protein expression. The aim of this project is to develop a novel method for measuring neuronal M2 expression in an animal model of asthma.