Disproportionation During Electrooxidation of Catecholamines at Carbon-Fiber Microelectrodes

Ciolkowski, Edward L.; Maness, Karolyn M.; Cahill, Paula S.; Wightman, R. Mark; Evans, Dennis H.; Fosset, Bruno; Amatore, Christian

doi:10.1021/ac00093a013

Cited by 106 publications

(82 citation statements)

References 30 publications

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“…The outside-out membrane-excised patch was held Ϸ1 m from the carbon fiber, which was held at ϩ700 mV for DA oxidation (14,25,26). The carbon fiber electrode did not affect voltage clamping of the patch membrane.…”

Section: Amperometrymentioning

confidence: 99%

Amphetamine induces dopamine efflux through a dopamine transporter channel

Kahlig

Binda²,

Khoshbouei³

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

260

219

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Drugs of abuse, including cocaine, amphetamine (AMPH), and heroin, elevate extracellular dopamine (DA) levels in the brain, thereby altering the activity͞plasticity of reward circuits and precipitating addiction. The physiological release of DA occurs through the calcium-dependent fusion of a synaptic vesicle with the plasma membrane. Extracellular DA is cleared by uptake through the Na ؉ ͞Cl ؊ -dependent DA transporter (DAT). In contrast, the substrate AMPH induces nonvesicular release of DA mediated by DAT. Extracellular AMPH is generally believed to trigger DA efflux through DAT by facilitating exchange for cytosolic DA. Here, in outside-out patches from heterologous cells stably expressing DAT or from dopaminergic neurons, by using ionic conditions in the patch pipette that mimic those produced by AMPH stimulation, we report that AMPH causes DAT-mediated DA efflux by two independent mechanisms: (i) a slow process consistent with an exchange mechanism and (ii) a process that results in rapid (millisecond) bursts of DA efflux through a channel-like mode of DAT. Because channel-like release of DA induced by AMPH is rapid and contains a large number of DA molecules, with a single burst of DA on par with a quantum of DA from exocytotic release of a vesicle, this burst mode of release may play a role in the synaptic actions and psychostimulant properties of AMPH and related compounds. Unlike AMPH, the endogenous substrate DA, when present on both sides of the plasma membrane, inhibits this channel-like activity, thereby suggesting that the DAT channel-like mode cannot accumulate DA against a concentration gradient.patch clamp ͉ amperometry D opamine (DA) transporter (DAT) is a member of a gene family that includes norepinephrine transporter (NET), serotonin transporter (SERT), and ␥-aminobutyric acid transporter 1 (GAT-1) (1-3). These neurotransmitter transporters are thought to play an important role in the reuptake (3, 4) and release (5, 6) of neurotransmitters. Their mechanism of transport is often described by using an alternating access model (7). In this model, the binding of cargo (DA, Na ϩ , and Cl Ϫ ) to an extracellularly oriented transporter induces a conformational rearrangement to an intracellularly oriented transporter from which the cargo is released into the cytosol, thereby completing the transport process. Consistent with this model, the recent crystal structure of the nonhomologous secondary transporter lactose permease (8) showed the transporter in what was inferred to be the ''inward-facing state'' with substrate bound within a cytoplasmic vestibule and no access route to the ''extracellular'' space.In the case of DAT, DA transport generates an electrical current because of the net movement of positive charge into the cell (9). DA efflux induced by the psychostimulant amphetamine (AMPH) is believed to result from the ability of AMPH to reverse this inward transport process, in that the inward transport of AMPH by DAT increases the number of ''inward-facing'' transporter binding sites and there...

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Section: Amperometrymentioning

confidence: 99%

Amphetamine induces dopamine efflux through a dopamine transporter channel

Kahlig

Binda²,

Khoshbouei³

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

260

219

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“…This leads to a sharp increase of the released flux of neurotransmitter that may be readily detected by amperometry using an "artificial synapse" configuration (see Figure 1A). [21][22][23][24][25][26][27][28] When this expansion terminates and the fusion pore stabilizes at its maximum opening radius R pore (see below), this flux decreases following an exponential clearing of the vesicle initial * Electrochemical Society Member.z E-mail: christian.amatore@ens.fr; zqtian@xmu.edu.cn content. [26][27][28] When monitored by amperometry at carbon fiber microelectrodes, i.e., through the 2e-oxidation of catecholamines, 23 this gives rise to the classical "spike" pattern shown in Figure 1A whose time-integration provides the detected charge Q, viz., the overall released quantity per vesicle through application of the Faraday law.…”

mentioning

confidence: 99%

How “Full” is “Full Fusion” during Exocytosis from Dense Core Vesicles? Effect of SDS on “Quantal” Release and Final Fusion Pore Size

Ren

Lin

et al. 2016

J. Electrochem. Soc.

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In this work, release was elicited from PC12 using sufficiently small concentrations of sodium dodecyl sulfate (SDS) to perturb normal release mechanism in an attempt to reveal concealed information while keeping physiologically compatible conditions. Amperometry was used to monitor and quantify the released fluxes and kinetics in individual vesicular events. This showed that stimulating release with SDS 350 μM leads to a doubling of the quantity of catecholamine cations released per event and much larger release fluxes as compared to controls (release elicited with K + 105 mM under same conditions) or SDS 250 μM. These quantitative measurements confirm our previous theoretical model and reports based on ex situ cytometric experiments on isolated PC12 vesicles, which established that release is far from being total under normal exocytotic conditions. Secondly, this establishes that the maximal size of fusion pores at the end of the "full fusion" phase is limited by some contraption unrelated to the membrane. Indeed, the present results are entirely consistent with the fact that SDS 350 μM allows the fusion pore to expand to a double size (ca. 28 nm radius) compared to controls and SDS 250 μM (ca. 14 nm radius). The considerable importance of the mechanism of vesicular exocytosis in biology and medicine [1][2][3][4][5][6] has stimulated an increasing number of reports. This high importance is evidenced, for example, by the award of two recent Nobel prizes in physiology and medicine bearing on these issues, the latest one being awarded in 2013 to James E. Rothman, Randy W. Schekman, and Thomas C. Südhof. [3][4][5][6] In neurons and endocrine cells neurotransmitters are stored and transported inside vesicles to be finally delivered at specific release sites of the outer cell membrane.7 Vesicles and cells membranes connect there through activation of SNAREs complexes following intracellular gated calcium ions influxes to form a nanometric fusion pore through which neurotransmitters can diffuse away.7-9 Most of the biochemical cellular processes regulating the formation and the intracellular traffic of these vesicles -as well as the corresponding biomolecular machineries involved -are now well established and documented. However, albeit this recognition, and after more than 20 years of important intensive and thoughtful works the crucial ultimate stages of the process which govern vesicular exocytotic events, viz., the very delivery of neurotransmitters in the extracellular space, are not fully understood beyond those relative to the transient initial fusion pore through which only a modest amount of neurotransmitters may be released 10-12 whose dimensions (ca. 1.2 nm radius) and fast dynamics (Kiss and Run) have been characterized by patch-clamp, [13][14][15][16][17][18] and very recently through amperometry. 19In endocrine cells, the main releasing stage involves a fast expansion of the initial fusion pore, generally thought to lead to a full incorporation of the former vesicle membrane into the cell one, 20 throug...

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“…Based on the square-scheme redox mechanism dominated by the adsorption/desorption processes established at classical carbon fiber disk electrodes, [17][18][19] one would expect the current peak intensities of the background corrected CVs, i p corr (v), to vary linearly with the scan rate over the range of scan rates considered in this study. However, the data reported in Figure 5a than that observed in the lower scan rate range (0.28 ± 0.01 nA.s.V −1 , Figure 5b and Table I).…”

Section: Discussionmentioning

confidence: 99%

“…with n = 2 19 and α = 0.36 as deduced from the E p i R−corr (v) vs. logv variations in Figure 4. Conversely, in the high scan rate one, one has:…”

Section: Discussionmentioning

confidence: 99%

“…2 or 3 we use a factor n rather than n 2 because the two electrons are not transferred simultaneously but sequentially through a ECEC square-scheme mechanism 60 in a sequence of two independent single electron transfer steps, 19 each one being followed by an acid-base reaction. 61 Within this framework, only the small population of h A h adsorbed dopamine molecules may be electroactive at high scan rates, giving rise to the small slope of the linear variations of i p corr (v) vs. v (Figures 5b, 5c and Table I).…”

Section: Discussionmentioning

confidence: 99%

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Surface Heterogeneities Matter in Fast Scan Cyclic Voltammetry Investigations of Catecholamines in Brain with Carbon Microelectrodes of High-Aspect Ratio: Dopamine Oxidation at Conical Carbon Microelectrodes

Oleinick

Álvarez‐Martos

Svir

et al. 2018

J. Electrochem. Soc.

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Fast Scan Cyclic Voltammetry (FSCV) at high aspect ratio carbon microelectrodes shows adequate high temporal and spatial resolution for in vivo analysis of catecholamines. Though the presence of their surface heterogeneities has been recognized since their earliest introduction for in vivo measurements in the brain, the kinetic consequences on the measurements have not been investigated and FSCV measurements are treated based on pre-and post-calibrations. We establish here that surface heterogeneities play a consequent dynamic role on the oxidation of dopamine taken as an example of catecholamines. Hence, the FSCV current peak intensities do not scale with the scan rate v or its square root. This is rationalized with a simple model involving a co-existence of at least two types of surface nanodomains with different electrochemical reactivities and different time responses. At low scan rates (<100 V s −1 ) dopamine molecules that initially adsorbed onto non-electroactive nanodomains have enough time to migrate toward highly electroactive ones so all molecules initially adsorbed on the whole electrode surface may be oxidized during one FSCV cycle. Current peak intensities then increase proportionally to the scan rate. However, above 100 V s −1 , dopamine migration between sites starts to be kinetically limited so that FSCV current peak intensities do not increase any more proportionally to the scan rate. Ultimately, i.e., above 1000 V s −1 , the dopamine exchange between sites is almost totally blocked so only dopamine molecules initially adsorbed on the electroactive surface nanodomains may be oxidized; the current peak intensities then increase again proportionally with the scan rate though with a smaller slope than that observed at small scan rates. Since carbon fibers with large aspect ratios are frequently used in brain investigations, this effect should be a concern when extracting quantitative results even when each carbon fiber response is properly pre-or post-calibrated using the exact CV waveform and scan rate used during the in vivo measurements. Release and modulation of neurotransmitters fluxes and concentrations are essential in complex organisms since they regulate many key functions by transferring information between cells such as neurons in the brain, neurons and muscle cells as well as through stimulating specific actions in endocrine-related systems. Albeit their unique and ubiquitous functions are well recognized today, the very existence and identification of neurotransmitters has long been a matter of debate up to the end of the second third of the past century, 1-3 and still needs to be better understood. This explains why characterizing fluxes and nature of neurotransmitters release is still stimulating a quest for analytical methods sufficiently accurate, specific and sensitive to investigate dynamic effluxes and flows of neurotransmitters in vivo (e.g., within a living brain) 4-6 or ex vivo (e.g., at the single endocrine cell level, 7-9 or intrasynaptically 10-12 ) with an adequate tempo...

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Disproportionation During Electrooxidation of Catecholamines at Carbon-Fiber Microelectrodes

Cited by 106 publications

References 30 publications

Amphetamine induces dopamine efflux through a dopamine transporter channel

Amphetamine induces dopamine efflux through a dopamine transporter channel

How “Full” is “Full Fusion” during Exocytosis from Dense Core Vesicles? Effect of SDS on “Quantal” Release and Final Fusion Pore Size

Surface Heterogeneities Matter in Fast Scan Cyclic Voltammetry Investigations of Catecholamines in Brain with Carbon Microelectrodes of High-Aspect Ratio: Dopamine Oxidation at Conical Carbon Microelectrodes

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