Figure 3From: Functional expression of a proton-coupled organic cation (H+/OC) antiporter in human brain capillary endothelial cell line hCMEC/D3, a human blood–brain barrier modelEffect of extracellular pH and intracellular pH on diphenhydramine uptake by hCMEC/D3 cells. (A) Uptake of diphenhydramine (30 μM) was measured at 37°C for 15 sec at medium pH values of 6.0, 7.4 and 8.4. Each column represents the mean ± S.E. of three determinations. Asterisks show a significant difference, *P<0.05 vs pH 7.4 (control). (B) Uptake of diphenhydramine (30 μM) was measured at 37°C, pH 7.4 for 15 sec. The uptake was measured in the presence of 30 mM NH4Cl to elevate intracellular pH (pHi) (NH4Cl (acute)). To measure the uptake at acidic pHi, extracellular NH4Cl was removed after preincubation with 30 mM NH4Cl for 20 min (NH4Cl (pre)). Each column represents the mean ± S.E. of three determinations. Asterisks show a significant difference, **P<0.01 vs control.Back to article page