Regulation of dopamine uptake in rat striatal tissue by NMDA receptors as measured using rotating disk electrode voltammetry

Rotating disk electrode (RDE) voltammetry was used to examine the effect of N-methyl- d-aspartate (NMDA) on the initial velocity of dopamine (DA) uptake in suspensions of rat striatal tissue. Transport velocities were determined by measuring the rate of clearance of 2 μM DA added to the tissue suspension. NMDA (200 μM) was found to increase the initial velocity of DA transport from 548 ± 28 to 803 ± 63 pmol/s per g tissue (mean ± SEM; P < 0.005). The increase was reversed by the competitive NMDA antagonist AP5, and thus appears to be receptor-mediated. In a separate experiment, lower concentrations of NMDA (20–100 μM) yielded a high correlation ( r = 0.96; P < 0.05) of velocity versus concentration. Kainic acid (10 μM) also was found to increase the initial rate of uptake, from 505 ± 34 to 702 ± 71 pmol/s per g ( P < 0.05). The results of this study indicate that the rate of DA uptake in the striatum can be modulated in vitro by presynaptic ionotropic glutamate receptors.