Effects of SK&F 96365, an inhibitor of receptor-mediated Ca2+ entry, on Ca2+ influx and catecholamine secretion in bovine adrenal chromaffin cells.
SK&F 96365 (1-[3-(4-methoxyphenyl)propoxyl]-1-(4-methoxyphenyl)ethyl-1H- imidazole HCl) (1-50 microM), an inhibitor of receptor-mediated Ca2+ entry, reduced both acetylcholine (ACh)- and 56 mM K+ (high K+)-induced 45Ca2+ influxes and catecholamine secretion in bovine adrenal chromaffin cells. However, SK&F 96365 at lower concentrations (1-3 microM) inhibited only ACh-induced 45Ca2+ influx and secretion but not their high K(+)-induction. In Na(+)-free medium, ACh-induced 45Ca2+ influx and secretion were also considerably decreased by SK&F 96365 at low concentrations (1-3 microM). These results suggest that in the chromaffin cells, not only voltage-sensitive calcium channels but also ACh receptor-operated calcium channels at least in part contribute to the influx of Ca2+ which triggers the catecholamine secretion from the cells when the cells are exposed by ACh.
Tachikawa
E
E
Department of Pharmacology, School of Medicine, Iwate Medical University, Morioka, japan.
Takahashi
S
S
Mizuma
K
K
Kondo
Y
Y
Kashimoto
T
T
Takahashi
E
E
D000109:Acetylcholine / Q000494:pharmacology; D000313:Adrenal Medulla / Q000187:drug effects*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects* / Q000378:metabolism; D002395:Catecholamines / Q000378:metabolism; D002417:Cattle; D005089:Exocytosis / Q000187:drug effects; D007093:Imidazoles / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D011978:Receptors, Nicotinic / Q000187:drug effects*; D015222:Sodium Channels / Q000378:metabolism
D015220:Calcium Channels; D002395:Catecholamines; D007093:Imidazoles; D011978:Receptors, Nicotinic; D015222:Sodium Channels; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole; D000109:Acetylcholine; D011188:Potassium; D002118:Calcium