Arterial ultrastructure determines drug distribution. Control or atherosclerotic arteries were incubated for 24h in fluorescent drug, serial sectioned and either analyzed for compositional distribution or imaged en face using a fluorescent microscope to determine drug distribution. (a,e) oil-red-O stain for lipid. (b,f) tubulin immunostain in brown; (c,g) VerHoeff stain shows elastin as black wavy lines; (d,h) fluorescent paclitaxel deposition (green). Diet and injury decreased total elastin and tubulin levels by 40±5% and 37±5%, respectively. Concomitantly, total fluorescent paclitaxel deposition dropped 73±9% and total lipid levels increased by 28±7%.