Fast-scan voltammetry of biogenic amines

Baur, John E.; Kristensen, Eric W.; May, Leslie J.; Wiedemann, Donna J.; Wightman, R. Mark

doi:10.1021/ac00164a006

Cited by 299 publications

(267 citation statements)

References 25 publications

(26 reference statements)

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“…With these methods, an area with high release can be targeted for measurements during an experiment. It has long been recognized that dopamine adsorbs to carbon-fiber microelectrodes (32 ). This adsorption process has two main consequences for the voltammetric signal (33 ).…”

Section: Temporal and Spatial Resolutionmentioning

confidence: 99%

“…One of the advantages of cyclic voltammetry is multiple point identification (each cyclic voltammogram contains ϳ1000 points), which allows numerous species with unique oxidation and reduction potentials to be detected and differentiated. Fast-scan cyclic voltammetry can be used to detect catecholamines, indolamines, neurotransmitter metabolites, ascorbic acid, oxygen, nitric oxide, and pH changes (32,(42)(43)(44). The compounds detected and the ability to resolve two compounds can depend on the applied waveform.…”

Section: Chemical Selectivitymentioning

confidence: 99%

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Detecting Subsecond Dopamine Release with Fast-Scan Cyclic Voltammetry in Vivo

et al. 2003

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Section: Temporal and Spatial Resolutionmentioning

confidence: 99%

Section: Chemical Selectivitymentioning

confidence: 99%

Detecting Subsecond Dopamine Release with Fast-Scan Cyclic Voltammetry in Vivo

et al. 2003

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“…The amplitude of amperometric foot currents is typically ~5 pA. Since most catecholamine molecules will be in monovalent cationic form but two electrons are transferred per molecule in the oxidation giving rise to the amperometric current 9 , the catecholamines released during the foot signal carry an ionic current of ~2.5 pA with them. This would charge a typical bovine chromaffin granule with 2.5 fF capacitance by 1 V/ms.…”

mentioning

confidence: 99%

Exocytotic catecholamine release is not associated with cation flux through channels in the vesicle membrane but Na+ influx through the fusion pore

2007

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Release of charged neurotransmitter molecules through a narrow fusion pore requires charge compensation by other ions. It has been proposed that this may occur by ion flow from the cytosol through channels in the vesicle membrane, which would generate a net outward current. We tested this hypothesis in chromaffin cells using cell-attached patch amperometry measuring simultaneously catecholamine release from single vesicles and ionic current across the patch membrane. No detectable current was associated with catecholamine release indicating that <2% (if any) of cations enter the vesicle through its membrane. Instead we show that flux of catecholamines through the fusion pore, measured as an amperometric foot signal, decreases when the extracellular cation concentration is reduced. The results reveal that the rate of transmitter release through the fusion pore is coupled to net Na + influx through the fusion pore as predicted by electrodiffusion theory applied to fusion pore permeation and suggest a prefusion rather than postfusion role for vesicular cation channels.Neurotransmitter and hormone release occurs by exocytosis, which begins with the formation of a narrow fusion pore 1,2 . Fusion pores in mast cells and chromaffin cells have typically an initial conductance of ~330 pS 1,3 through which vesicular serotonin and catecholamines are released, respectively 4,5 . The initial fusion pore of a synaptic vesicle is typically >280 pS and release of neurotransmitter should occur with a time constant <500 μs due to the small vesicle volume 6 . Many neurotransmitters and hormones are organic ions that carry charge with them. Among these acetylcholine, serotonin and catecholamines are mostly monovalent cations at physiological or more acidic vesicular pH. Efflux of charged molecules through a narrow fusion pore would rapidly charge the small capacitance of the vesicle and a mechanism of charge compensation is required.Release of catecholamines from a single vesicle can be detected electrochemically 7 . The initial flux of catecholamines through the early narrow fusion pore can be measured as an amperometric foot signal preceding the amperometric spike 3,5,8 . The amplitude of amperometric foot currents is typically ~5 pA. Since most catecholamine molecules will be in monovalent cationic form but two electrons are transferred per molecule in the oxidation giving rise to the amperometric current 9 , the catecholamines released during the foot signal carry an ionic current of ~2.5 pA with them. This would charge a typical bovine chromaffin granule 4correspondence should be addressed to M.L. (ml95@cornell.edu).

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“…These amperometric techniques can detect quantal release of oxidizable transmitters, such as the catecholamines epinephrine and norepinephrine, using a carbon fiber or platinum microelectrode that is positioned close to the cell surface and held at a potential that is sufficiently high to oxidize the released molecules. Upon release from a vesicle, the catecholamine molecules that diffuse to the surface of the electrode are rapidly oxidized, resulting in the transfer of two electrons to the electrode [4]. The oxidation of the molecules released in a single quantal event thus generates a transient oxidation current with a duration of a few milliseconds.…”

Section: Introductionmentioning

confidence: 99%

Design of a CMOS Potentiostat Circuit for Electrochemical Detector Arrays

Ayers

Gillis

Lindau

et al. 2007

IEEE Trans. Circuits Syst. I

101

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High-throughput electrode arrays are required for advancing devices for testing the effect of drugs on cellular function. In this paper, we present design criteria for a potentiostat circuit that is capable of measuring transient amperometric oxidation currents at the surface of an electrode with submillisecond time resolution and picoampere current resolution. The potentiostat is a regulated cascode stage in which a high-gain amplifier maintains the electrode voltage through a negative feedback loop. The potentiostat uses a new shared amplifier structure in which all of the amplifiers in a given row of detectors share a common half circuit permitting us to use fewer transistors per detector. We also present measurements from a test chip that was fabricated in a 0.5-μm, 5-V CMOS process through MOSIS. Each detector occupied a layout area of 35μm × 15μm and contained eight transistors and a 50-fF integrating capacitor. The rms current noise at 2kHz bandwidth is ≈ 110fA. The maximum charge storage capacity at 2kHz is 1.26 × 10 6 electrons.

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Fast-scan voltammetry of biogenic amines

Cited by 299 publications

References 25 publications

Detecting Subsecond Dopamine Release with Fast-Scan Cyclic Voltammetry in Vivo

Detecting Subsecond Dopamine Release with Fast-Scan Cyclic Voltammetry in Vivo

Exocytotic catecholamine release is not associated with cation flux through channels in the vesicle membrane but Na+ influx through the fusion pore

Design of a CMOS Potentiostat Circuit for Electrochemical Detector Arrays

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