Rotating disk electrode voltammetric measurements of dopamine transporter activity: an analytical evaluation

Rotating disk electrode (RDE) voltammetry at glassy carbon electrodes in 300- to 500-microL volumes has been shown in the literature by this laboratory and others to be useful in measuring dopamine and norepinephrine inward transport and release in preparations from rat brain and in expression systems. However, an analytical evaluation of the technique has not been made, and it is presented here in studies in striatal suspensions and human embryonic kidney cells expressing the human transporter for dopamine. The RDE was found to be able to measure dopamine and its metabolites with linear responses over the range of physiologically relevant concentrations with practical limits of quantification in the 10 to 50 nM range without signal and/or signal to noise enhancements. Response times of the technique were found to vary between 20 and 60 ms depending on rotation rate. Release and inward transport velocities were shown to be kinetically resolved. The glassy carbon electrode was found to be useful for several years at physiological temperatures without significant changes in electrochemical surface area, residual current, or response factors. Some sources of error in the measurement of release and inward transport values of velocity were noted and described.