title: Simultaneous real-time amperometric measurement of catecholamines and serotonin at carbon fibre 'dident' microelectrodes.
abstract: Amperometry allows real-time measurement of in vivo electrochemical signals, albeit with no capacity to identify the constituents of the signal. In the present study, differential amperometry was used to monitor catecholamine and serotonin (5-HT) simultaneously at the same location. 'Dident' carbon fibre microelectrodes (microelectrodes with two working electrodes in a single assembly) were constructed and coated with Nafion to prevent poisoning on contact with brain tissue. One electrode (channel A) was held at +200 mV versus Ag/AgCl to monitor catecholamines selectively. This potential is too low to oxidise 5-HT. The second electrode (channel B), recording faradaic current at +500 mV versus Ag/AgCl, measured the sum of catecholamine and 5-HT oxidation. The 5-HT current component was the difference of channel B minus channel A. With appropriate balancing of the two channels, it is possible to record catecholamines and 5-HT simultaneously at the same dident microelectrode. Examples of measurements in striatum, cortex and locus coeruleus are shown.
authors.affiliation: Neurotransmission Laboratory, Academic Department of Anaesthesia and Intensive Care, Barts and the London School of Medicine and Dentistry, Alexandra Wing, Anaesthetic Unit, Royal London Hospital, Whitechapel, London E1 1BB, UK.
authors.forename: James M
authors.initials: JM
authors.lastname: Pennington
authors.forename: Julian
authors.initials: J
authors.lastname: Millar
authors.forename: Clinton P
authors.initials: CP
authors.lastname: L Jones
authors.forename: Catarina A
authors.initials: CA
authors.lastname: Owesson
authors.forename: Daniel P
authors.initials: DP
authors.lastname: McLaughlin
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Stamford
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000295:instrumentation / Q000379:methods*; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism; D001923:Brain Chemistry / Q000502:physiology*; D002244:Carbon / Q000737:chemistry; D000077482:Carbon Fiber; D002395:Catecholamines / Q000032:analysis*; D004594:Electrophysiology / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D008839:Microelectrodes / Q000592:standards; D008995:Monoamine Oxidase / Q000235:genetics; D009448:Neurochemistry / Q000295:instrumentation / Q000379:methods*; D009924:Organ Culture Techniques; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000032:analysis*; D018030:Silver Compounds; D013997:Time Factors
chemical_list: D000077482:Carbon Fiber; D002395:Catecholamines; D018030:Silver Compounds; D012701:Serotonin; D002244:Carbon; D008995:Monoamine Oxidase; C037548:silver chloride