CHARACTERIZATION AND TISSUE DISTRIBUTION OF H-3 HISTAMINE-RECEPTORS IN GUINEA-PIGS BY N-ALPHA-METHYLHISTAMINE

We have used [3H]Nα-methylhistamine to characterize H3-binding in the guinea pig brain and to study its tissue distribution. Kinetic and equilibrium binding experiments indicate a single class of high affinity sites in membranes isolated from guinea pig brain tissue (Kd = 0.4 nM, Bmax = 41 fmol/mg of protein). Competition binding experiments have confirmed that this ligand associates with H3-receptors and, under the conditions used in these experiments, does not bind to H1- or H2-receptors. Although there was some binding in the ileum and large intestine, H3-binding was found primarily in the central nervous system. © 1990.