Effect of imipramine on high potassium evoked 3H-dopamine release in the rat striatum

The effects of three different types of dopamine (DA) uptake inhibitor, imipramine, cocaine and nomifensine, were examined on high potassium evoked 3H-DA release using tissues obtained from rat striatum by a micropuncture technique. Imipramine caused an increase in 3H-DA efflux and this imipramine-induced efflux is Ca2+-independent. Moreover, imipramine reduced the high potassium evoked release, and at 50 microM, the release by potassium stimulation was entirely abolished. These results support that imipramine depletes vesicular DA which is released by potassium stimulation as well as an inhibitory effect on DA uptake. However, nomifensine dose not have such an effect.