Analysis of Muscarinic Acetylcholine Receptor Expression and Function

Muscarinic acetylcholine receptors (mAChRs) are members of the G proteinlinked receptor superfamily and are expressed in many cell types and tissues, including brain, peripheral nerves, cardiac and smooth muscles, and exocrine glands (1,2). Five subtypes of mAChR, encoded by distinct genes, have been identified in mammals, and homologous mAChR genes have been isolated from nonmammalian vertebrates (3) and invertebrates (4). This chapter will describe techniques we have used for the analysis of the number and ligandbinding properties of muscarinic receptors in intact cells and in membrane homogenates, the measurement of coupling of mAChR to changes in intracellular second messengers, the analysis of changes in G protein expression that may contribute to changes in mAChR-mediated signaling, and the quantitative measurement of mRNAs encoding specific subtypes of mAChR.