The norepinephrine-sensitive Ca2+-storage site differs from the caffeine-sensitive site in vascular smooth muscle of the rat aorta.
Using microfluorometry of quin 2, a Ca2+-sensitive dye, we characterized the release and uptake of Ca2+ by the norepinephrine-sensitive Ca2+-storage site and the caffeine-sensitive one. The norepinephrine-sensitive Ca2+-storage site was readily depleted in Ca2+-free medium and almost completely replenished by loading with 1.0 mM Ca2+ solution for 3 min, whereas the caffeine-sensitive site was scarcely affected. Furthermore, norepinephrine has little effect on the caffeine-sensitive Ca2+-storage site in Ca2+-free medium, and vice versa. We conclude that the location and mechanisms of release and uptake of Ca2+ of these two Ca2+-storage sites differ in the case of rat aortic vascular smooth muscle cells in primary culture.
D000634:Aminoquinolines; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000378:metabolism; D001693:Biological Transport, Active / Q000187:drug effects; D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology*; D051381:Rats
D000634:Aminoquinolines; D002110:Caffeine; C035739:Quin2; D002118:Calcium; D009638:Norepinephrine