Development of a high-throughput fluorescent no-wash sodium influx assay
Fig 3
Food dyes in the red-violet color range quench the background fluorescence of the sodium indicator ANG-2.
(A) Sample traces of the fluorescence levels of NaV1.7-HEK cells with ANG-2 and PSS buffer addition, with and without washing, obtained using the FLIPRTETRA. (B) Sample traces of the fluorescence level of NaV1.7-HEK cells with ANG-2 following the addition of Brilliant Black BN (1 mM), Carmine (1 mM), Ponceau 4R (1 mM), Allura Red (1 mM) or Amaranth (1 mM) obtained using the FLIPRTETRA. (C) The average relative light units corresponding to 60–100 s after addition of quenchers or buffer. Reduction in background fluorescence by Brilliant Black BN (1 mM), Carmine (1 mM), Ponceau 4R (1 mM), Allura Red (1mM) and Amaranth (1 mM) was not significantly different to washing. Statistical significance was determined using one-way ANOVA with Dunnett’s post-test, *P < 0.05 compared to wash. (D-H) Concentration-response curves for the reduction in background fluorescence of NaV1.7-HEK cells with ANG-2 by quenchers Brilliant Black BN, Carmine, Ponceau 4R, Allura Red and Amaranth. Data are presented as mean ± SEM from three wells.