Simultaneous measurements of Ca2+ and nitric oxide in bradykinin-stimulated vascular endothelial cells.
The production of endothelium-derived relaxing factor (EDRF), known to be nitric oxide (NO), is triggered by a rise in the cytoplasmic calcium concentration ([Ca2+]i) subsequent to receptor binding of vasoactive agonists. In vascular endothelial cells, NO is synthesized from L-arginine by the Ca2+/calmodulin-dependent NO synthase. In this study, we report the first simultaneous measurements of [Ca2+]i and [NO] at the level of single endothelial cells. In cultured bovine aortic endothelial cells, extracellular application of bradykinin (BK, 10 to 20 mumol/L) caused transient (sometimes oscillatory) increase in [Ca2+]i, which was measured with the fluorescent Ca2+ indicator fura 2 and fluorescence imaging microscopy. BK caused an increase in [Ca2+]i, primarily through release from intracellular stores. Under identical experimental conditions, BK caused a transient increase in [NO], which was measured by application of a porphyrinic NO microsensor. [NO] peaked at approximately 0.5 mumol/L. Simultaneous measurements of [Ca2+]i and [NO] in BK-stimulated endothelial cells revealed that a transient increase in [Ca2+]i was rapidly followed by an increase in [NO] that outlasted the [Ca2+]i transient.
Blatter
L A
LA
Department of Physiology, Loyola University Chicago, Maywood, Ill, USA.
Taha
Z
Z
Mesaros
S
S
Shacklock
P S
PS
Wier
W G
WG
Malinski
T
T
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D002118:Calcium / Q000032:analysis*; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009569:Nitric Oxide / Q000032:analysis*
D009569:Nitric Oxide; D001920:Bradykinin; D002118:Calcium