Differential cell permeability of amiloride derivatives.

(A) The structures of amiloride and the two C(5) derivatives employed in these studies are depicted. The Bn in the UCD38B structure refers to a benzyl group. (B) MDA-MB-231 cells were incubated with vehicle control or 250 µM amiloride, UCD74A or UCD38B for 10 minutes and rinsed with PBS. Treated cells were then imaged by brightfield (upper panels) or fluorescence (lower panels) microscopy, the fluorescence intensities of 20 randomly selected cells were quantified, and averages with standard error are indicated.