Specific binding of 3H-mepyramine to histamine H1 receptors in intestinal smooth muscle

THE specific binding of high-affinity ligands to a wide range of pharmacological receptors has been used to obtain information on receptor numbers, distribution and the characteristics of agonist and antagonist binding. The first study of this type, by Paton and Rang 1 , was of the binding of 3 H-atropine to muscarinic receptors in guinea pig intestinal smooth muscle. The histamine H 1 receptor has not previously been studied, and here we describe the specific binding of mepyramine, an H 1 -selective antagonist 2 , to histamine H 1 receptors in homogenates of the longitudinal muscle-myenteric plexus preparation from guinea pig small intestine.