title: Mass spectrometry "sensor" for in vivo acetylcholine monitoring.
abstract: Developing sensors for in vivo chemical monitoring is a daunting challenge. An alternative approach is to couple sampling methods with online analytical techniques; however, such approaches are generally hampered by lower temporal resolution and slow analysis. In this work, microdialysis sampling was coupled with segmented flow electrospray ionization mass spectrometry (ESI-MS) to perform in vivo chemical monitoring. The use of segmented flow to prevent Taylor dispersion of collected zones and rapid analysis with direct ESI-MS allowed 5 s temporal resolution to be achieved. The MS "sensor" was applied to monitor acetylcholine in the brain of live rats. The detection limit of 5 nM was sufficient to monitor basal acetylcholine as well as dynamic changes elicited by microinjection of neostigmine, an inhibitor of acetylcholinesterase, that evoked rapid increases in acetycholine and tetrodotoxin, a blocker of Na(+) channels, that lowered the acetylcholine concentration. The versatility of the sensor was demonstrated by simultaneously monitoring metabolites and infused drugs.
authors.affiliation: Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States.
authors.forename: Peng
authors.initials: P
authors.lastname: Song
authors.forename: Neil D
authors.initials: ND
authors.lastname: Hershey
authors.forename: Omar S
authors.initials: OS
authors.lastname: Mabrouk
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Slaney
authors.forename: Robert T
authors.initials: RT
authors.lastname: Kennedy
mesh_terms: D000109:Acetylcholine / Q000032:analysis* / Q000378:metabolism; D000110:Acetylcholinesterase / Q000378:metabolism*; D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D017551:Microdialysis / Q000379:methods*; D008845:Microinjections; D009388:Neostigmine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D026941:Sodium Channel Blockers / Q000494:pharmacology; D015222:Sodium Channels / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013779:Tetrodotoxin / Q000494:pharmacology; D013997:Time Factors
chemical_list: D002800:Cholinesterase Inhibitors; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D009388:Neostigmine; D013779:Tetrodotoxin; D000110:Acetylcholinesterase; D000109:Acetylcholine