title: In vitro continuous amperometric monitoring of 5-hydroxytryptamine release from enterochromaffin cells of the guinea pig ileum.
abstract: A diamond microelectrode was used to sensitively, reproducibly and stably record overflow of 5-hydroxytryptamine (5-HT, serotonin) from enterochromaffin cells (EC) of the intenstinal mucosal layer. 5-HT is an important neurotransmitter and paracrine signalling molecule in the gastrointestinal tract. The diamond microelectrode was formed by overcoating a sharpened 76 microm diameter Pt wire with a thin layer of conducting diamond. After insulation with polypropylene, the conically-shaped microelectrode had a diameter of about 10 microm at the tip and 80 microm at the cylindrical portion. The exposed length was 100-200 microm. Continuous amperometry with the microelectrode poised at a detection potential of 700 mV vs. Ag|AgCl was used to measure 5-HT overflow as an oxidation current. 5-HT overflow was elicited by both mechanical and electrical stimulation. Some minor electrode fouling, a common problem with the oxidative detection of 5-HT, was seen for diamond but the response stabilized enabling recording in vitro. Both 5-HT and the paracrine hormone, melatonin, were detected in the extracellular solution. The 5-HT oxidation current increased in the presence of the serotonin transporter (SERT) inhibitor, fluoxetine (1 microM), providing evidence that the oxidation current was associated with 5-HT.
authors.affiliation: Department of Bioengineering, Imperial College London, London, SW7 2AZ, UK. bhavik.a.patel@imperial.ac.uk
authors.forename: Bhavik Anil
authors.initials: BA
authors.lastname: Patel
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Bian
authors.forename: Veronika
authors.initials: V
authors.lastname: Quaiserová-Mocko
authors.forename: James J
authors.initials: JJ
authors.lastname: Galligan
authors.forename: Greg M
authors.initials: GM
authors.lastname: Swain
mesh_terms: D000818:Animals; D002244:Carbon; D018130:Diamond; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods; D004759:Enterochromaffin Cells / Q000187:drug effects / Q000378:metabolism*; D005473:Fluoxetine / Q000494:pharmacology; D006168:Guinea Pigs; D007082:Ileum; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism*; D008839:Microelectrodes; D012701:Serotonin / Q000378:metabolism*; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology
chemical_list: D002244:Carbon; D018130:Diamond; D005473:Fluoxetine; D012701:Serotonin; D017367:Selective Serotonin Reuptake Inhibitors