Intracellular free calcium transients induced by norepinephrine in rat aortic smooth muscle cells in primary culture.
In cultured rat arterial smooth muscle cells treated with quin 2, cytosolic Ca2+ transients induced by norepinephrine were recorded microfluorometrically. In the presence or absence of extracellular Ca2+, norepinephrine induced transient and dose-dependent elevations in cytosolic Ca2+, with a similar time course, the peak levels being observed at 2 min. These transient elevations in cytosolic Ca2+ were dose-dependently inhibited by alpha-adrenergic antagonists, the order of potency being prazosin greater than phentolamine greater than yohimbine, irrespective of the presence of extracellular Ca2+. We propose that with or without extracellular Ca2+, norepinephrine activates mainly alpha-1 adrenoceptors leading to a release of Ca2+ from intracellular stores. This would explain the transient elevation in cytosolic Ca2+ in rat aortic vascular smooth muscle cells in primary culture.
D000634:Aminoquinolines; D000818:Animals; D002118:Calcium / Q000502:physiology*; D002478:Cells, Cultured; D003592:Cytophotometry; D003593:Cytoplasm / Q000502:physiology; D007700:Kinetics; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology*; D051381:Rats; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*
D000634:Aminoquinolines; D011942:Receptors, Adrenergic, alpha; C035738:Quin2-acetoxymethyl ester; D002118:Calcium; D009638:Norepinephrine