The nitric oxide donor, sodium nitroprusside, increased intranuclear and cytosolic free calcium concentration in single PU5-1.8 cells.
In the present study, the effect of sodium nitroprusside (SNP), a nitric oxide (NO) releasing agent, on the intracellular free calcium concentration ([Ca2+]i) was studied. Our results demonstrate that SNP could increase [Ca2+]i in single PU5-1.8 cells, a murine macrophage cell line, as determined by confocal laser scanning microscope with calcium green-1 fluorescent probe. In the presence of hemoglobin, a NO scavenger, the effect of SNP on the Ca2+ level was suppressed. Our data also show that the intranuclear Ca2+ ([Ca2+]n) was always higher than those in cytosol. Stimulation of cells with 1mM SNP induced an immediate increase of [Ca2+]n with a delayed rise of cytosolic Ca2+ ([Ca2+]c). Interestingly, when cells were subsequently treated with 2mM SNP, an increase of [Ca2+]c with a similar pattern to the rise [Ca2+]n was observed. In Ca(2+)-free buffer, SNP also raised the [Ca2+]n and [Ca2+]c. When Ca2+ was added to the buffer, a second peak of [Ca2+]n and several spikes of [Ca2+]c were observed. These results thus indicate that 1) NO may increase both [Ca2+]n and [Ca2+]c in PU5-1.8 cells; 2) the increase of [Ca2+]n requires both internal and external Ca2+. Moreover, the diverse responses in these cells suggest that the regulation of Ca2+ in these areas may be different.
Kong
S K
SK
Department of Biochemistry, Chinese University of Hong Kong Shatin, NT.
Choy
Y M
YM
Lee
C Y
CY
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D009569:Nitric Oxide / Q000378:metabolism*; D009599:Nitroprusside / Q000494:pharmacology*
D009599:Nitroprusside; D009569:Nitric Oxide; D002118:Calcium