Quantitation of in vivo measurements with carbon fiber microelectrodes

Fast-scan cyclic voltammetry (FSCV) at carbon fiber disk microelectrodes an d quantitative microdialysis were used to measure striatal concentration ch anges of N-acetyl-p-aminophenol (APAP, acetaminophen) following an intraper itoneal injection of 75 mg/kg APAP in rats. The goal of this work was to de termine which in vitro calibration procedure, precalibration or postcalibra tion, gave the most accurate results when using carbon fiber microelectrode s in vivo. Voltammetric detection of APAP in vivo was complicated with norm al electrodes by interference from pH changes. An electrode treatment was u sed to minimize electrode sensitivity to pH and this allowed successful APA P detection. In vitro calibrations of the treated carbon fiber disk microel ectrodes before and after the in vivo experiment were used to calculate APA P concentration changes measured in vivo and compared to microdialysis resu lts. The maximal striatal APAP concentration determined by microdialysis, a djusted for in vitro recovery, was 23.I mu M. The electrochemical results w ere approximately two times greater (postcalibration) or smaller (precalibr ation) than the microdialysis result. (C) 2000 Elsevier Science B.V. All ri ghts reserved.