Diverse effects of monensin on capacitative Ca2+ entry and release of stored Ca2+ in vascular smooth muscle cells.
The effects of monensin, an activator of Na(+)/H(+) exchanger (NHE), on capacitative Ca(2+) entry (CCE) were investigated using A7r5 cells. Capacitative Ca(2+) entry was induced by elevation of extracellular Ca(2+) concentrations of A7r5 cells in which stored Ca(2+) had been depleted by previous administration of thapsigargin. Capacitative Ca(2+) entry was abolished by pretreatment of the cells with SKF-96365 (1-[beta-(3-[4-methoxyphenyl]propoxy)-4-methoxyphenethyl]-1H-imidazole hydrochloride) but was not affected by pretreatment with verapamil. Monensin significantly increased capacitative Ca(2+) entry. On the other hand, 5-hydroxytryptamine-induced inositol monophosphate accumulation and subsequent intracellular Ca(2+) release from its stores were significantly inhibited by monensin, while thapsigargin-induced Ca(2+) release was not affected by monensin. These results suggest that monensin has diverse actions on capacitative Ca(2+) entry and agonist-induced release of stored Ca(2+) in vascular smooth muscle cells.
Wakabayashi
Ichiro
I
Department of Hygiene and Preventive Medicine, School of Medicine, Yamagata University, Iida-Nishi 2-2-2, Yamagata 990-9585, Japan. wakabaya@med.id.yamagata-u.ac.jp
Marumo
Mikio
M
Sotoda
Yoko
Y
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D007476:Ionophores / Q000494:pharmacology*; D008985:Monensin / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010716:Phosphatidylinositols / Q000096:biosynthesis; D012701:Serotonin / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology
D007476:Ionophores; D010716:Phosphatidylinositols; D012701:Serotonin; D019284:Thapsigargin; D008985:Monensin; D002118:Calcium