The Measurement of Monoamine Neurotransmitters in Microdialysis Perfusates Using HPLC-ECD

Microdialysis is a perfusion-based sampling procedure that is now used routinely to study the chemistry of the extracellular environment of a variety of tissues in the living organism (1 ,2 ). A microdialysis probe (consisting of an inlet and outlet tube connected by an area of semipermeable membrane) is perfused at a constant flow rate with a medium (artificial cerebrospinal fluid, CSF; aCSF) that is iso-osmotic to and contains ions at the same concentration as the extracellular fluid. Analytes pass through the semipermeable membrane down their concentration gradient and are swept through the probe by the constantly moving perfusion medium. Once collected, samples can then be analyzed by a variety of different analytical procedures.