Abstract
The affinity of a 1, 4-dihydropyridine (DHP) type calcium channel blocker, NZ-105 ((±)-2-[benzyl(phenyl)amino]ethyl 1, 4-dihydro-2, 6-dimethyl-5 (5, 5-dimethyl-2-oxo-1, 3, 2-dioxaphosphorinan-2-yl)-4-(3-nitrophenyl)-3-pyridinecarboxylate hydrochloride ethanol), on the DHP-binding site in the central nervous system and various receptor sites were compared with nicardipine and diltiazem by the use of a receptor binding assay technique. NZ-105 exhibited a displacement effect against [3H]nimodipine in the rat brain DHP-binding site with a potency similar to that of nicardipine. Nicardipine also inhibited the specific binding of several other [3H]-labelled ligands to their receptor such as adrenergic α1, α2, β, dopamine D1, D2, opioid μ, δ, and κ-type receptors. Diltiazem also showed a similar inhibitory property. However, NZ-105 showed only weak inhibition against the binding to these receptors. These results suggest that Z-105 has strong affinity to the DHP-binding site in voltage-dependent calcium channels with higher specificity.
