Figure 5.

pABA treated bEnd.3 cells: Effect of transport inhibitors on CoQ₁₀ transport. CoQ₁₀ (pre-incubated in serum) transport across pABA treated (1 mM; 5 days) bEnd.3 cells on Transwell filters assayed over 60 min. Inhibitors added apically and basally two hours before assay were BLT-1 (10 µM) for SR-B1, FPS-ZM1 (1 µM) for RAGE, RAP (0.5 µM) for LRP-1/LDLR and verapamil (0.1 mM) for p-glycoprotein. Apparent permeability, Papp, shown for (a) Apical to Basal CoQ₁₀ transport, (b) Basal to Apical CoQ₁₀ transport. (c) The “net” transport of CoQ₁₀ across bEnd.3 cells, calculated from the difference between A to B transport (blood to brain) and B to A transport (brain to blood). “Net” transport in pABA treated control cells was Apical to Basal, toward the brain side. * Treatment with RAGE inhibitor, FPS-ZM1 (1 µM), abolished “net” A to B transport. ^† Treatment with LRP-1/LDLR inhibitor RAP (0.5 µM), enhanced “net” +ve transport toward the brain side (A to B). The SR-B1 and p-glycoprotein inhibitors BLT-1 (10 µM) and Verapamil (0.1 mM), had no significant effect on “net” transport. (d) Schematic summary of CoQ₁₀ transport across a CoQ₁₀ deficient BBB. “Net” transport shifts toward to the brain side. Uptake via RAGE but SR-B1 is absent. Leaky tight junctions facilitate extra transfer across the BBB. Efflux via LRP-1 is retained. (e) Transport of the CoQ₁₀ analogue, idebenone. Apical to Basal transport exceeded Basal to Apical, meaning there was “net” transport toward the brain. n = 6; values are mean ± SEM * p < 0.05. (f) FITC-40 Apical to Basal transport; n = 4–7; values are mean ± SEM; * p < 0.05, ** p < 0.01; ANOVA single factor; post-hoc Bonferroni.