Binding Tests in Respiratory System

Purpose and Rationale Histamine receptors have been classified on the basis of pharmacological analysis (Hill et al. 1997). Histamine exerts its action via at least four receptor subtypes. The H1 receptor couples mainly to Gq/11, thereby stimulating phospholipase C, whereas the H2 receptor interacts with Gs to activate adenylyl cyclase. The histamine H3 and H4 receptors couple to Gi proteins to inhibit adenylyl cyclase and to stimulate MAPK (Hough 2001). Histamine is considered to play a major role in asthmatic attacks (Bryce et al. 2006). H1 antagonists have been used since decades as therapeutic agents. This assay is used to determine the affinity of test compounds to the histamine H1 receptor by measuring their inhibitory activities on the binding of the H1 antagonist H-pyrilamine to a plasma membrane preparation from guinea pig brain.