DIRECT COMPARISON OF THE RESPONSE OF VOLTAMMETRY AND MICRODIALYSIS TOELECTRICALLY-EVOKED RELEASE OF STRIATAL DOPAMINE

Carbon fiber microelectrodes either were implanted directly into stria tal tissue or were mounted into the outlet of microdialysis probes tha t were implanted into striatal tissue, This allowed voltammetry and mi crodialysis to be used under identical in vivo experimental conditions to monitor extracellular dopamine levels dur ing electrical stimulati on of the medial forebrain bundle both before and after uptake inhibit ion with nomifensine. The marked differences between the results obtai ned with each technique cannot be explained on the basis of their inhe rent analytical attributes (sensitivity, temporal response, etc.), The results demonstrate that the microdialysis recovery factor for endoge nous dopamine increases after uptake inhibition, an observation that s tands in contradiction to the existing theory and practice of the micr odialysis technique. The observations led to the development of a nume rical model that rationalizes the observations reported herein and tha t allows in vivo voltammetry and in vivo microdialysis results to be i nterpreted within a single theoretical framework.