Microdialysis recovery of serotonin released in spinal cord dorsal horn

Methods for making and using hollow microdialysis fibers suitable for recovering extracellular substances from discrete regions of the spinal cord are described. After placement of the fiber, artificial cerebrospinal fluid was pushed through it at a low (4-5 microliters/min) rate. The perfusate was collected and samples analyzed on a high performance liquid chromatograph with an electrochemical detector. Serotonin, 5-hydroxyindole acetic acid and norepinephrine were recovered and identified. Single unit extracellular recordings were made during the perfusion and collection; thus simultaneous observation of neurotransmitter release and modulation of single cell activity is now possible.