title: Enhancement of brain calcium antagonist binding by phencyclidine and related compounds.
abstract: The abilities of compounds structurally or pharmacologically related to phencyclidine to increase the apparent affinity of the [3H]dihydropyridine calcium channel antagonist [3H]nitrendipine were examined in lysed synaptosomal membrane preparations of rat brain. The p-bromo analog of phencyclidine (1-(1-(4-bromophenyl)cyclohexyl)piperidine) was the most efficacious compound tested in enhancing the apparent affinity of [3H]nitrendipine. The efficacy of this compound was approximately two-fold greater than PCP. The stereoisomers of PCMP (1-(1-phenylcyclohexyl-3-methylpiperidine) were also more efficacious than phencyclidine, although only a small degree of stereoselectivity was observed. Levoxadrol, dexoxadrol and the enantiomers of ketamine did not potentiate [3H]nitrendipine binding. The enantiomers of SKF 10047 (n-allylormetazocine), dextrorphan, levorphanol and the ion channel toxins histrionicotoxin and pumiliotoxin-B also increased the apparent affinity of [3H]nitrendipine, while several local anesthetics and mu-opiate receptor ligands were without effect. These studies suggest that the ability of phencyclidine and structurally related compounds to increase the apparent affinity of [3H]nitrendipine is not mediated through an interaction with phencyclidine receptors, but may represent a unique site for allosteric modulation of neuronal dihydropyridine calcium channel antagonist binding sites.
mesh_terms: D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000378:metabolism*; D004110:Diltiazem / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009294:Narcotics / Q000494:pharmacology; D009498:Neurotoxins / Q000494:pharmacology; D009543:Nifedipine / Q000031:analogs & derivatives / Q000378:metabolism; D009568:Nitrendipine; D010622:Phencyclidine / Q000031:analogs & derivatives / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D000779:Anesthetics, Local; D002121:Calcium Channel Blockers; D009294:Narcotics; D009498:Neurotoxins; D009568:Nitrendipine; D004110:Diltiazem; D009543:Nifedipine; D010622:Phencyclidine