Fig. 4.

Trans-stimulation of [³H]-nicotine transport at the BBB. [³H]-nicotine brain distribution volume (V _brain; in microliter per gram) was measured after in situ mouse brain perfusion with Krebs carbonate buffer (pH_e 7.40) for 60 s, followed by a 60-s washout step without [³H]-nicotine. The last 60 s perfusion was at pH_e 6.40 without (Control) or with 10 mM of an unlabelled test compound (diphenhydramine, N-methyl naloxone, naloxone, morphine, or tramadol). Data represent the means ± SD of six to eight animals. *p < 0.05, ***p < 0.001 for comparisons between experimental and control groups