MULTIMEMBRANE CARBON-FIBER ELECTRODES FOR PHYSIOLOGICAL MEASUREMENTS OF NITRIC-OXIDE

Carbon fiber electrodes were chemically modified with polymeric membra nes of nickel porphyrin, Nafion, immobilized ascorbic acid oxidase and either polylysine or polypyridinium to provide selectivity of anodic detection of nitric oxide (NO) in physiological systems. These composi te electrodes were demonstrated to preclude interference by physiologi cal concentrations of electroactive species and by L-arginine (L-Arg), N-nitro-L-arginine methyl ester (L-NAME) and carbon monoxide (GO). Th e composite electrode response time was 500 ms and the chronocoulometr ic detection limit was 0.5 nM NO. In situ measurement of NO was demons trated in brain slices in vitro and in the anesthetized brain in vivo with detection limits of 8 acid 173 nM NO in these tissue preparations , respectively.