Rhodamine 123 distribution is altered in the presence of verapamil.

<p>A) Dye distribution and quantification experiments using rhodamine 123 (R123) were performed as described for Figure 1. Graph shows mean fluorescent intensity (± std dev.) for each treatment. Rhodamine 123 (grey bars), a substrate for mammalian ABCB1, ABCB4 and ABCB5, was excluded from the brain by 8 d.p.f. which, coincides with the onset of zebrafish Abcb/4/5 staining in the vasculature of the CNS. When 8 d.p.f. and 10 d.p.f. larvae were incubated with verapamil (white bars), an inhibitor of ABCB1, ABCB4 and ABCB5 in mammals, R123 failed to be excluded, consistent with blocked Abcb1/4/5 function. B and C) Representative images of parasagittal section of 5 d.p.f. larvae following pericardial injection of saline (B) or Rhodamine 123 (C). Fluorescence in the brain is observed following injection of Rhodamine 123. Scale bar represents 50 µm.