3H]mepyramine binding to histamine H 1 receptors in bovine retina

Abstract

The promethazine-sensitive [ 3H]mepyramine binding was used to determine the presence of histamine H 1 receptors in membranes from bovine retina. Specific mepyramine binding to retinal membranes was reversible, saturable and of high affinity. The apparent dissociation constant (K D=2.2±0.4 nM) and the density of binding sites (B max=60.9±5.1 fmol/mg protein), obtained in equilibrium studies, were similar to those found in bovine brain cortex. Binding was stereospecific and the inhibitory potencies of H 1 and H 2 antagonists indicated that [ 3H]mepyramine binding sites in the retina have characteristics of H 1 receptors.