Electrochemical monitoring of biogenic amine neurotransmission in real time

Three techniques, constant-potential amperometry, high-speed chronoamperome try, and fast-scan cyclic voltammetry, have been used extensively to invest igate the rapid events associated with neurotransmission. These techniques vary in sensitivity, chemical resolution and temporal resolution. Amperomet ry provides the best temporal resolution but little chemical resolution. Fa st-scan cyclic voltammetry provides both good temporal and chemical resolut ion, while high-speed chronoamperometry offers good temporal resolution and moderate chemical resolution. The amount of chemical information which is needed for a neurochemical measurement depends upon the sample. For single cells, secondary methods, such as HPLC and capillary electrophoresis, offer extensive chemical information about the contents of a cell. With this inf ormation, chemical information is not needed during the electrochemical mea surement. Therefore, amperometry is employed to obtain the greatest tempora l resolution. However, when using more complex biological samples, such as brain slices or in vivo implantation, there is a greater demand for chemica l resolution provided by the electrochemical measurement. To bolster result s, further confirmation is sought from anatomical, physiological and pharma ceutical evidence. Within this review, the three electrochemical techniques are outlined and compared. Examples are then provided of measurements whic h have been made in the three predominant biological samples which have bee n studied: single cells, brain slices and intact animals. (C) 1999 Elsevier Science B.V. All rights reserved.