Intracellular alkalinization augments capacitative Ca2+ entry in vascular smooth muscle cells.
Agonist-induced Ca2+ influx of vascular smooth muscle cells is thought to be triggered by depletion of intracellular Ca2+ stores. This study investigated the effects of intracellular alkalinization on capacitative Ca2+ entry in A7r5 rat aortic smooth muscle cells. Intracellular alkalinization was induced by NH(4)Cl. Transplasmalemmal Ca2+ influx due to Ca2+ store depletion induced by thapsigargin, which was abolished by pretreatment of the cells with SKF-96365 but not affected by that with verapamil, was significantly increased by pretreatment with NH(4)Cl. Neither 5-hydroxytryptamine-induced inositol monophosphate accumulation nor intracellular Ca2+ release from its stores was affected by NH(4)Cl. These results suggest that intracellular alkalinization acts on the process(es) after depletion of Ca2+ stores and facilitates capacitative Ca2+ entry 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
D000643:Ammonium Chloride / Q000494:pharmacology*; D000818:Animals; D001011:Aorta / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002478:Cells, Cultured; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007295:Inositol Phosphates / Q000096:biosynthesis; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D010716:Phosphatidylinositols / Q000378:metabolism; D051381:Rats; D012701:Serotonin / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology; D013997:Time Factors; D014661:Vasoconstriction / Q000187:drug effects
D015220:Calcium Channels; D007295:Inositol Phosphates; D010716:Phosphatidylinositols; D000643:Ammonium Chloride; D012701:Serotonin; D019284:Thapsigargin; D000252:Calcium-Transporting ATPases; D002118:Calcium