Evidence for distinct 5-hydroxytryptamine2 binding site subtypes in cortical membrane preparations.
5-Hydroxytryptamine (5-HT) displays a sixfold higher affinity for 5-HT2 binding sites labeled by [3H]ketanserin in rat (IC50 = 200 +/- 40 nM) and human (IC50 = 190 +/- 50 nM) cortex than for 5-HT2 sites in bovine cortex (IC50 = 1,200 +/- 130 nM). 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 (+/-)-[3H]4-bromo-2,5-dimethoxyamphetamine ([3H]DOB) binding in the rat indicates a population of binding sites with a KD of 0.38 +/- 0.04 nM and a Bmax of 1.5 +/- 0.05 pmol/g tissue. In contrast, specific [3H]DOB binding cannot be detected in bovine cortical membranes. These data indicate that species variations exist in 5-HT2 binding site subtypes and that [3H]ketanserin appears to label a homogeneous population of 5-HT2 binding site subtypes in bovine cortex.
Pierce
P A
PA
Department of Neurology, Stanford University Medical Center, California 94305.
Peroutka
S J
SJ
D004290:DOM 2,5-Dimethoxy-4-Methylamphetamine / Q000031:analogs & derivatives / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism*; D006801:Humans; D007650:Ketanserin / Q000378:metabolism; D051381:Rats; D011985:Receptors, Serotonin / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism; D013045:Species Specificity
D011985:Receptors, Serotonin; D004290:DOM 2,5-Dimethoxy-4-Methylamphetamine; C003943:2,5-dimethoxy-4-bromoamphetamine; D012701:Serotonin; D007650:Ketanserin