Voltammetric monitoring of brain extracellular levels of serotonin, 5-hydroxyindoleacetic acid and uric acid as assessed by simultaneous microdialysis.

We have previously developed a microcomputer-assisted curve-fitting method for measuring the components of the mixed electrochemical signals recorded by differential normal pulse voltammetry in the living brain. It was initially used for resolution of the dopamine and dihydroxyphenylacetic acid components of the catechol signal (peak 2). This report shows how it can be applied to analysis of the indoleamine/uric acid (UA) components of the more complex peak 3. The voltammogram is modeled as a mixture of 3 normal curves of known parameters corresponding to the oxidation of UA, 5-hydroxyindoleacetic acid and serotonin, which is solved by non-linear iterative procedures. Performance was assessed by treatments with drugs having well-known effects on the substances monitored, pargyline and allopurinol, and by the chromatographic analysis of microdialysates collected simultaneously from the contralateral side.