The effect of apomorphine and bradykinin on uptake and release of dopamine in vitro by striatal synaptosomes of the rat.

Apomorphine (APO), 10(-5) and 10(-4) M, inhibited 3H-dopamine (DA) uptake by rat striatal synaptosomes. Bradykinin (BRS) produced a biphasic effect: at low concentration (1.6 x 10(-7) it potentiated, while in higher (1.6 x 10(-5) inhibited DA uptake. Only the low concentration of BRS potentiated the already weak effect of APO, 10(-5) M, on DA uptake. In concentrations 10(-5) and 10(-4) M, APO facilitated the release of radioactivity from synaptosomes preincubated with 3H-DA. BRS potentiated this effect, particularly that evoked by the high concentration of APO. The results indicate that BRS may potentiate the action of APO on the uptake and release of dopamine by rat striatal synaptosomes in vitro.