title: Characteristics of the inhibition of ligand binding to serotonin receptors in rat brain membranes by verapamil.
abstract: Characteristics of the interaction of verapamil with serotonin receptors were studied in rat brain membranes using a radioligand binding technique. While verapamil competed for the [3H]ketanserin binding sites at low concentrations with the Ki value of 0.41 microM, much higher concentrations were needed to inhibit the binding of [3H]serotonin to its binding sites, indicating higher affinity of verapamil binding for 5-HT2 than 5-HT1 receptors. The inhibitory action of verapamil on the [3H]ketanserin binding was stereoselective; the (-)isomer was about ten times more potent than the (+)isomer. The interaction of verapamil with [3H]-ketanserin was competitive and reversible. While D600, a verapamil derivative, also competed for the [3H]ketanserin binding sites, nifedipine and nicardipine had practically no ability to inhibit the ligand binding to 5-HT1 or 5-HT2 receptors. Although diltiazem competed for 5-HT2 receptors, the affinity was much less than verapamil and D600.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D066298:In Vitro Techniques; D007650:Ketanserin / Q000378:metabolism; D008297:Male; D008566:Membranes / Q000378:metabolism; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000032:analysis / Q000187:drug effects* / Q000378:metabolism; D014700:Verapamil / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D011985:Receptors, Serotonin; D007650:Ketanserin; D014700:Verapamil