3H-imipramine uptake into rat striatal slices and imipramine-induced 3H-dopamine efflux

The effect of imipramine on spontaneous efflux of radiolabelled dopamine (DA) from slices of rat striatum was examined by a superfusion method. Imipramine at concentrations of 10 - 100 microM enhanced the efflux of DA accumulated in a high-affinity uptake system in a concentration-dependent manner. This efflux of 3H-DA was not affected by conditions (Ca2+-free medium, 100 microM bretylium and 30 microM tetrodotoxin) which inhibited the release of 3H-DA by electrical stimulation. Furthermore, this imipramine-induced 3H-DA efflux was temperature-dependent. The uptake of 3H-imipramine into striatal slices was determined. This uptake was concentration- and temperature-dependent and increased linearly. These results are discussed in relation to the hypothesis that 3H-DA efflux by imipramine is connected with uptake of imipramine.