*5.8. Aβ Transport Assay in Isolated Brain Capillaries*

To determine P-gp-mediated transport of Aβ, freshly isolated brain capillaries from WT and P-gp KO mice were incubated for 1 h at room temperature with HiLyte™-hAβ<sup>42</sup> (5 µM; [18,72,86]). For each group, images of 10 capillaries were acquired by confocal microscopy (Zeiss LSM 710 inverted confocal microscope, 40× 1.2 NA water immersion objective, 488 nm line of argon laser, Carl Zeiss Inc., Thornwood, NY, USA). Images were analysed by quantitating luminal HiLyte™-hAβ<sup>42</sup> fluorescence using ImageJ software v1.48. Specific, luminal HiLyte™-hAβ<sup>42</sup> fluorescence was taken as the difference between total luminal fluorescence and fluorescence in the presence of the P-gp-specific inhibitor PSC833 (5 µM; [18,72,86]).
