In vitro assessment for vascular selectivity of a new dihydropyridine derivative, NB-818.
Eur J Pharmacol
; 301(1-3): 99-106, 1996 Apr 22.
Article
em En
| MEDLINE
| ID: mdl-8773452
ABSTRACT
The vascular selectivity of NB-818 (isopropyl methyl 2-carbamoyloxymethyl-6-methyl-4-(2,3-dichlorophenyl)-1,4-dihydropyridine -3, 5-dicarboxylate), a newly synthesized dihydropyridine derivative, was evaluated in in vitro experiments. NB-818 and nifedipine concentration dependently caused a relaxant effect in rabbit femoral arteries precontracted with 60 mM K+, a negative inotropic effect in guinea-pig papillary muscles, and a negative chronotropic effect in guinea-pig right atria. The onset of these inhibitory effects of NB-818 was much slower than that of nifedipine when compared at concentrations producing the same inhibition. The relaxant effect of NB-818 was about 10 times more potent than that of nifedipine, while the negative inotropic effect of NB-818 was about 100 times less potent than that of nifedipine. As a result, NB-818 showed about 300 times higher vascular selectivity than nifedipine. The two drugs exhibited a similar potency for the negative chronotropic effect. In a whole-cell configuration with voltage clamp, the blocking effect of NB-818 on L-type Ca2+ current (ICa) in guinea-pig ventricular cells appeared much more slowly than that of nifedipine and was hardly washed out. The potency of NB-818 to block ICa was markedly enhanced under depolarized conditions (i.e. at a holding potential of -30 mV) compared to that under polarized conditions (i.e. at a holding potential of -70 mV). Such a voltage-dependent blocking action on ICa was less pronounced for nifedipine. These results indicate that NB-818 is a slow-acting Ca2+ channel antagonist with much high vascular selectivity. Its vascular selectivity may be at least in part related to the marked voltage-dependent inhibition of ICa.
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Temas:
ECOS
/
Aspectos_gerais
Bases de dados:
MEDLINE
Assunto principal:
Vasos Sanguíneos
/
Di-Hidropiridinas
/
Bloqueadores dos Canais de Cálcio
/
Músculo Liso Vascular
Limite:
Animals
Idioma:
En
Revista:
Eur J Pharmacol
Ano de publicação:
1996
Tipo de documento:
Article
País de afiliação:
Japão