Table 19.2 Comparison of in vitro and in situ Kd values for various Ca2+ indicators.

Indicator Kd in vitro (nM) * Kd in situ (nM) † Cell/Tissue Type
Calcium Green-1 190 930 HeLa cells ref
Fluo-3 390 2570 Frog skeletal muscle ref
Fluo-4 345 1000 HeLa cells ref
Fura-2 145 371 U373-MG astrocytoma cell ref
Fura-2 145 350 Rabbit gastric gland ref
Indo-1 230 844 Rabbit cardiac myocyte ref
Oregon Green 488 BAPTA-1 170 430 HeLa cells ref
Rhod-2 570 720 Mouse heart ref
* Values determined at 22°C in 100 mM KCl, 10 mM MOPS, pH 7.2, 0–10 mM CaEGTA. † Values determined in the cellular environments listed in the adjacent column.