Calcium buffering capacity of neuronal cell cytosol measured by flash photolysis of calcium buffer NP-EGTA.
N1E-115 mouse neuroblastoma cells were injected with a calcium buffer/indicator solution to allow both ratiometric measurement of free calcium concentration and the release of calcium ions upon UV flash. The solution contained sulforhodamine, a marker dye used to estimate the volume injected; fluo-3, a calcium indicator, and NP-EGTA, a high affinity calcium-selective buffer that is converted by UV flash to products with negligible calcium affinity. The calcium increase recorded upon UV irradiation (Delta[Ca2+]i) was small for small injection volumes, increased with larger injection volumes, but approached a plateau at the largest injection volumes. From this relation we estimate the buffering capacity of the cytosol as 1700 ions bound per ion free.
Fleet
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A
School of Biomedical Sciences, University of St. Andrews, Fife, KY16 9AJ, Scotland.
Ellis-Davies
G
G
Bolsover
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S
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D051379:Mice; D009447:Neuroblastoma / Q000378:metabolism*; D010782:Photolysis; D014407:Tumor Cells, Cultured
D002118:Calcium