Monitoring Amino Acid Neurotransmitter Release in the Brain by In Vivo Microdialysis

Microdialysis is a frequently used technique to collect continuously in vivo various endogenous chemical substances from the extracellular space of discrete brain regions. In comparison to other sampling methods (such as the push-pull technique), microdialysis causes only minor tissue trauma. This feature makes microdialysis the technique of choice when studying in vivo extracellular transmitter levels in relationship to diverse physiological and pathophysiological processes in several species, including humans (1 ,2 ). Because of limitations of the technique, microdialysis methods are unsuitable for analysts of rapid, transient changes in extracellular transmitter levels. The microdialysis technique is, however, well suited to detect slow alterations in neurotransmitter concentrations, as occurring, for example, during ischemia (3 ).