Figure 3. Effects of inhibitors of OCT3 on [³H]-MPP⁺ outflow.

A, inhibition of [³H]-MPP⁺ release by 2 μM cyanine 863 (indicated by horizontal bar) in the presence of 0.5 μM desipramine. Desipramine was added to the superfusion buffer 10 min before collection of 4 min fractions was started. AUC (-4.74 %) was calculated as shown in Fig. 2B. B, same experimental approach as shown in A, but with results expressed as fractional rates. Bar indicates the presence of 2.0 μM cyanine 863. Data points are means ± s.e.m. from 3 individual cultures included in the same release experiment. C, inhibition of MPP⁺ release by 30 μM corticosterone (indicated by horizontal bar) in the presence of 0.5 μM desipramine. Desipramine was added to the superfusion buffer 10 min before collection of 4 min fractions was started. AUC (-4.02 %) was calculated as shown in Fig. 2B. D, fractional rates of radioactive outflow in the absence or presence of 2 μM cyanine 863 alone (indicated by bar). E, AUC values of [³H]-MPP⁺ outflow in the presence of cyanine 863 (0.5 and 2.0 μM), 30 μM oestradiol (Estr), or 100 μM d-tubocurarine (d-TC). Bars indicate means ± s.e.m. from 14 (0.5 μM Cy), 16 (2.0 μM Cy), 21 (30 μM Estr), and 9 individual cultures (100 μM d-TC). None of the AUC values is significantly different from zero (P > 0.05, Mann-Whitney U test). F, AUC values of MPP⁺ outflow in the presence of indicated substances. All cultures were treated with 0.5 μM desipramine 10 min before and during collection of 4 min fractions, except Cy 2.0 – Des, where 2.0 μM cyanine instead of desipramine was included in the superfusion buffer before and during the experiments, and where desipramine was probed for an inhibition of radioactive outflow. Abbreviations for substances are identical to E (plus Cortico: corticosterone). Bars indicate means ± s.e.m. from 8 (2.0 μM Cy), 6 (10 μM Cy), 6 (30 μM Estr), 6 (30 μM Cortico), 6 (100 μM d-TC), and 14 individual cultures (2.0 Cy – 0.5 μM Des). Significantly different from zero: * P < 0.05, ** P < 0.01 (Mann-Whitney U test).