Acylating phencyclidines irreversibly enhance brain calcium antagonist binding.
Phencyclidine was previously shown to allosterically increase the apparent affinity of the dihydropyridine ( [3H]nitrendipine) calcium antagonist binding site in a lysed synaptosomal membrane preparation of rat forebrain. Treatment of a similar preparation of mouse forebrain with 4-isothiocyanato-1-(1-phenylcyclohexyl) piperidine (FOURPHIT), an acylating phencyclidine derivative, resulted in a concentration dependent (0.1-10 microM), irreversible, increase in the apparent affinity of [3H]nitrendipine in contrast to the effects of phencyclidine which were reversible. The FOURPHIT isomer, 1-[1-(3-isothiocyanatophenyl) cyclohexyl] piperidine (METAPHIT), (10 microM) also irreversibly increased the apparent affinity of [3H]nitrendipine, but was much less efficacious than FOURPHIT. Phencyclidine blocked the irreversible increase in the apparent affinity of [3H]nitrendipine produced by FOURPHIT. The interactions of multivalent cations and the calcium antagonist diltiazem with the [3H]nitrendipine binding site were altered following treatment of membranes with FOURPHIT. These studies suggest that FOURPHIT irreversibly interacts with the same sites as PCP, and thus may be a useful tool with which to further probe both the behavioral and biochemical interactions between phencyclidine and the dihydropyridine calcium antagonist binding site.
D000818:Animals; D001921:Brain / Q000378:metabolism*; D008297:Male; D008566:Membranes / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D009543:Nifedipine / Q000031:analogs & derivatives* / Q000378:metabolism; D009568:Nitrendipine; D010622:Phencyclidine / Q000031:analogs & derivatives / Q000494:pharmacology*; D013268:Stimulation, Chemical
C044705:metaphit; D009568:Nitrendipine; D009543:Nifedipine; D010622:Phencyclidine