Functional implications of Ca2+ mobilizing properties for nitric oxide production in aortic endothelium.
We have investigated the relationship between Ca2+ mobilization and the cellular production of nitric oxide (NO) by using fura-2 and diaminofluorescein-2 (DAF-2), an NO-sensitive dye, in bovine aortic endothelial cells (BAEC). High concentrations of ATP (100 microM) or thapsigargin (1 micro M) depleted intracellular Ca2+ store sites with a single Ca2+ transient, and induced an increase in DAF-2 fluorescence even in Ca2+-free solution, thereby indicating that store depletion leads to NO production. The same level of increase in DAF-2 fluorescence was elicited by low concentrations of ATP (1 micro M), which induced Ca2+ oscillations but did not deplete store sites, only in the presence of extracellular Ca2+. Furthermore, inhibition of ATP (1 micro M)-induced Ca2+ entry with La3+ suppressed DAF-2 fluorescence. ATP (0.3 micro M), applied in Ca2+-free, Mn2+-containing solution induced Mn2+ entry-coupled fura-2 quenching, repeating shortly after each oscillation peak. These results indicate that NO is produced preferentially by entered Ca2+, and that Ca2+ oscillations, which are induced by low levels of stimulation, play a significant role in NO production by strongly modulating Ca2+ entry.
Koyama
Tetsuya
T
Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University, 812-82, Fukuoka, Japan.
Kimura
Chiwaka
C
Park
Sung Jin
SJ
Oike
Masahiro
M
Ito
Yushi
Y
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019793:Fluorescein; D005456:Fluorescent Dyes; D009569:Nitric Oxide / Q000096:biosynthesis*; D019284:Thapsigargin / Q000494:pharmacology
D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D009569:Nitric Oxide; D000001:Calcimycin; D019284:Thapsigargin; D000255:Adenosine Triphosphate; D002118:Calcium; D019793:Fluorescein