Figure 3

Effect 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.