Table 1.

Sr2+ binding affinities of buffers, indicators, and photolyzable chelators used in this study

BufferKd, Ca2+Kd, Sr2+SourceFactor Sr2+/Ca2+
CDTA0.011 μm4.4 μmMartell and Smith, 1974400
EGTA0.15 μm35 μmMartell and Smith, 1974233
HEDTA2.5 μm62 μmMartell and Smith, 197425
ATP214 μm724 μmWilson and Chin, 19913.4
fura-20.22 ± 0.007 μm (n = 3)4.8 ± 0.22 μm (n = 7)Calibration22
fura-4F1.1 μm32 ± 0.7 μm (n = 3)Calibration28
fura-6F8.4 μm134 μmCalibration16
fura-2FF6.1 μmCalibration
DMN0.005 μm0.160 μmCalibration44