Endothelin-sensitive intracellular Ca2+ store overlaps with caffeine-sensitive one in rat aortic smooth muscle cells in primary cultures.
We made use of quin2 microfluorometry to determine the effects of endothelin (ET) on cytosolic free Ca2+ concentrations [Ca2+]i) in rat aortic smooth muscle cells in primary culture. In Ca2+-containing medium, ET induced a rapid and sustained elevation of [Ca2+]i. In the latter component, in particular, the elevation of [Ca2+]i was inhibited by diltiazem. In Ca2+-free medium, ET induced a rapid and transient [Ca2+]i elevation, which was not inhibited by diltiazem. When the caffeine-sensitive intracellular Ca2+ store was practically depleted by repeated treatment with caffeine in Ca2+-free media, ET did not elevate [Ca2+]i. Thus, it was suggested that ET induces [Ca2+]i elevation not only by extracellular Ca2+-dependent, mechanisms but also by releasing Ca2+ from the intracellular store, and that the ET-sensitive Ca2+ store may overlap with the caffeine-sensitive one, in cultured vascular smooth muscle cells.
Kai
H
H
Research Institute of Angiocardiology, Faculty of Medicine, Kyushu University, Kukuoka, Japan.
Kanaide
H
H
Nakamura
M
M
D000634:Aminoquinolines; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000378:metabolism*; D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D004110:Diltiazem / Q000494:pharmacology; D016232:Endothelins; D004730:Endothelium, Vascular / Q000502:physiology*; D005456:Fluorescent Dyes; D007700:Kinetics; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D010455:Peptides / Q000494:pharmacology*; D051381:Rats
D000634:Aminoquinolines; D016232:Endothelins; D005456:Fluorescent Dyes; D010455:Peptides; D002110:Caffeine; D004110:Diltiazem; C035739:Quin2; D002118:Calcium