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Evidence for Distinct 5‐Hydroxytryptamine 2 Binding Site Subtypes in Cortical Membrane Preparations
Author(s) -
Pierce Pamela A.,
Peroutka Stephen J.
Publication year - 1989
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1989.tb09171.x
Subject(s) - ketanserin , binding site , population , cortex (anatomy) , cerebral cortex , biology , serotonin , receptor , 5 ht receptor , microbiology and biotechnology , chemistry , biophysics , endocrinology , biochemistry , neuroscience , medicine , environmental health
Abstract: 5‐Hydroxytryptamine (5‐HT) displays a sixfold higher affinity for 5‐HT 2 binding sites labeled by [ 3 H]ketanserin in rat (IC 50 = 200 ± 40 n M ) and human (IC 50 = 190 ± 50 n M ) cortex than for 5‐HT 2 sites in bovine cortex (IC 50 = 1,200 ± 130 n M ). The Hill slopes of the 5‐HT competition curves are 0.67 ± 0.04 in rat, 0.69 ± 0.08 in human, and 0.96 ± 0.02 in bovine cortex. Scatchard analysis of (±)‐( 3 H]4‐bromo‐2,5‐dimethoxyamphetamine ([ 3 H]DOB) binding in the rat indicates a population of binding sites with a K D of 0.38 ± 0.04 n M and a B max of 1.5 ± 0.05 pmol/g tissue. In contrast, specific [ 3 H]DOB binding cannot be detected in bovine cortical membranes. These data indicate that species variations exist in 5‐HT 2 binding site subtypes and that [ 3 H]ketanserin appears to label a homogeneous population of 5‐HT 2 binding site subtypes in bovine cortex.