values (A, B) and mean recoveries (C, D) for Na-F and LY through hCMEC/D3, hBMEC, and TY10 monolayers. 24-Well tissue culture inserts from Greiner Bio-one® (transparent PET membrane, 3.0 μm pore size, 0.6 × 106 pores/cm2) were used (n = 3–5). A, B: Lowest paracellular permeability of Na-F and LY was obtained through hBMEC monolayers (5.08 ± 0.220 × 10-6 cm/s and 5.39 ± 0.364 × 10-6 cm/s, respectively). All experiments for Na-F permeability were carried out at the time indicated with a black arrow in Figures 3A-D. For LY, permeability measurements were carried out at TEER values in the same range (graphs not shown). C, D: Mean recoveries of Na-F in all experiments were in the range of 75% and 87%. For LY, mean recoveries varied between 66% and 79%. *cultured with initial medium; **cultured with growth medium 20% FBS.