Figure 4.

A (±)Methamphetamine (methamph) increased both non-vesicular and vesicular [³H]dopamine release from rat striatum. For the experimental procedure, see Figure 2A,B. (A) The releasing effect of (±)methamphetamine on resting [³H]dopamine efflux was concentration-dependent in a range of 1 to 10 µmol/L. The estimated concentration of (±)methamphetamine that increased resting [³H]dopamine release by 50% above control release was 3.2 µmol/L. One-way ANOVA followed by the Dunnett’s test, F(3,20) = 35.14, p < 0.001, (±)methamphetamine in 6.75 and 10 μmol/L concentrations significantly increased non-vesicular [³H]dopamine release, p < 0.01, mean ± S.E.M., n = 4-8. (B) (±)Methamphetamine was added to striatal slices from fraction 8 in a concentration of 6.75 µmol/L and maintained throughout the experiment. Resting [³H]dopamine release (defined as fractional release between fractions 8 and 17) was 0.37 ± 0.08 in control and 4.27 ± 0.46 percent of the content in the presence of (±)methamphetamine, p < 0.001. The electrical stimulation-induced [³H]dopamine release (S2/S1) was 0.89 ± 0.03 in control and 1.86 ± 0.32 in response to (±)methamphetamine, p < 0.01. Student t-statistics for two-means, mean ± S.E.M., n = 8-8.