Table 4

Potency of fluorescein analogs to inhibit [3H]P1075 binding to rabbit skeletal muscle membranes.

CompoundR4R5R6R7RR2′R4′R5′R7′Ki
μm
FluoresceinHHHHOHHHHH>100
GalleinHHHHOHHOHOHH64  ± 1.3
DichlorofluoresceinHHHHOHClHHCl>100
Fluorescein isothiocyanateHNCSHHOHHHHH11  ± 4
Eosin YHHHHOHBrBrBrBr6.5  ± 0.7
EthyleosinHHHHOC2H5 BrBrBrBr0.2  ± 0.07
Eosin isothiocyanateHNCSHHOHBrBrBrBr2.9  ± 1
Eosin maleimideHN(CO)2CCHHOHBrBrBrBr8.7  ± 2
Eosin iodoacetamideHNHCOCH2lHHOHBrBrBrBr2.4  ± 0.5
Phloxine BClClClClOHBrBrBrBr0.2  ± 0.05
Rose bengalClClClClOHllll0.3  ± 0.1

Competition curves were obtained using 14 nm[3H]P1075, and Ki values were calculated from the Cheng and Prusoff equation (16). Values are mean ± standard error of three experiments with different membrane preparations.  


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