Quantification of rhodamine B (RhB) dye accumulation in zebrafish embryos. (A) Amounts of RhB accumulated in 1 hpf, 6 hpf, 12 hpf, 24 hpf and 48 hpf zebrafish embryos that, simultaneously to RhB, were exposed to various concentrations of transporter inhibitors cyclosporin A (CsA), PSC833 or MK571. (B) Amounts of RhB accumulated in 48 hpf zebrafish embryos upon morpholino knock-down of Abcb4 (Abcb4-SP-MO/Abcb4-ATG-MO) or Abcb5 (Abcb5-SP-MO). Controls contained dye only (ctrl, ctrl-MO), the morpholino control (ctrl-MO) served to exclude unspecific morpholino effects on dye accumulation in the embryos. Experiments with CsA (5 μM CsA, ctrl-MO + 5 μM CsA) were set up as comparisons for the effects of this pharmacologic transporter inhibitor on RhB accumulation in the embryos. Values are means +/− standard deviations from three independent experiments. Statistically significant differences from controls were determined with one-way analysis of variance (ANOVA), followed by Dunnett’s test and are indicated by asterisks (P <0.05).