A Theoretical Description of Microdialysis with Mass Transport Coupled to Chemical Events

Yang, Hua; Peters, Jennifer L.; Allen, C. R.; Chern, Shyh-Shi; Coalson, and Rob D.; Michael, Adrian C.

doi:10.1021/ac991186r

Cited by 42 publications

(58 citation statements)

References 23 publications

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“…These concentrations are consistent with those in the literature when accounting for differences in in vitro recovery of the dialysis probes [3,[23][24][25]. (Although in vitro recovery is not always an accurate reflection of in vivo recovery [26], this correction facilitates comparison to literature values.) Basal concentrations of taurine, glutamine and serine are not listed because the peaks for these analytes were typically off-scale when the detector settings were optimized for sensitivity; however, use of automatic gain control or data acquisition boards with greater dynamic range will allow these compounds to quantified from the same electropherograms as the lower level compounds.…”

Section: Selectivitysupporting

confidence: 84%

In vivomonitoring of amine neurotransmitters using microdialysis with on-line capillary electrophoresis

2001

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Microdialysis sampling was coupled via a flow-gated interface on-line to capillary electrophoresis with laser-induced fluorescence (LIF) detection for in vivo monitoring of neuroactive amino acids and amines. In the instrument, analytes are derivatized precolumn with o-phthaldehyde and beta-mercaptoethanol to form fluorescent isoindole products. The instrument was improved over previous designs by incorporating a sheath-flow cuvette for reduced background in LIF detection which improved sensitivity by 15-fold. The methodology was improved by utilizing a voltage ramped injection which allowed generation of 500000 theoretical plates with 20 s separations. Resolution of the isoindole derivatives was further improved by addition of hydroxypropyl-modified beta-cyclodextrin to the electrophoresis buffer. The new instrumentation and methods allow resolution and detection of glutamate, gamma-aminobutyric acid, glycine, aspartate, serine, taurine, glutamine and dopamine (if levels are elevated) collected from in vivo sampling probes every 20 s. The technique is suited to continuous monitoring for dynamic measurements of these compounds in vivo.

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Section: Selectivitysupporting

confidence: 84%

In vivomonitoring of amine neurotransmitters using microdialysis with on-line capillary electrophoresis

2001

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“…In contrast, microdialysis results report increases of Ϸ8-fold, which would correspond to 40 nM extracellular dopamine (3), a value more than an order of magnitude less than the current estimate. Although disturbances of the tissue with either probe (44)(45)(46) or errors in calibration may account for this large difference, differences in sampling region are also a likely factor. The carbon-fiber electrode is Ϸ40-fold shorter and 50-fold smaller in diameter than typical microdialysis probes.…”

Section: Discussionmentioning

confidence: 99%

Real-time measurement of dopamine fluctuations after cocaine in the brain of behaving rats

Heien

Khan

Ariansen

et al. 2005

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

439

469

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Dopamine neurotransmission has been implicated in the modulation of many cognitive processes. Both rapid (phasic) and slower (tonic) changes in its extracellular concentration contribute to its complex actions. Fast in vivo electrochemical techniques can measure extracellular dopamine on a rapid time scale but without the selectivity afforded with slower techniques that use chemical separations. Cyclic voltammetry improves chemical resolution over other electrochemical methods, and it can resolve dopamine changes in the brains of behaving rodents over short epochs (<10 s). With this method, however, selective detection of slower dopamine changes is still elusive. Here we demonstrate that principal component regression of cyclic voltammetry data enables quantification of changes in dopamine and extracellular pH. Using this method, we show that cocaine modifies dopamine release in two ways: dopamine concentration transients increase in frequency and magnitude, whereas a gradual increase in steady-state dopamine concentration occurs over 90 s.cyclic voltammetry ͉ nucleus accumbens ͉ principal component regression F ast changes in the extracellular concentration of neurotransmitter can arise from phasic neuronal firing, whereas longlasting changes are associated with tonic firing (1). Dopaminergic neurons exhibit both of these firing patterns. Phasic activity accompanies salient stimuli, whereas tonic firing regulates the steady-state extracellular concentration (2). For this reason, chemical sensors for dopamine should be able to operate on a wide range of time scales in behaving animals. Microdialysis, a commonly used in vivo chemical sampling technique, is well suited to measure the minute-to-minute changes (tonic) that occur after uptake inhibition by agents such as cocaine (3,4). In vivo voltammetry, another approach for dopamine sampling, can measure much faster events, enabling phasic dopamine changes to be measured (5).A limitation of all voltammetric techniques has been their chemical selectivity. Fast-scan cyclic voltammetry at carbonfiber microelectrodes (6) provides rapid measurements and yields a chemical signature, the cyclic voltammogram, that allows distinction among electroactive molecules that are present in the brain. The electrode is highly sensitive to dopamine relative to dihydroxyphenylacetic acid and ascorbate, two major interferants, and the voltammogram of dopamine is distinct from those for a variety of neurochemical substances, although it is the same as that for norepinephrine (7). However, measurements in behaving rats have revealed that rapid dopamine changes are usually accompanied by other rapid changes in the electrochemical signal (5,8,9). Measurements with ion-selective electrodes demonstrated that these signals arise from a change in the pH of the brain extracellular fluid (10). Therefore, an objective method is needed to resolve the detected chemical events, assign them to specific compounds, and evaluate their temporal characteristics.Voltammetric electrodes are similar to othe...

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“…A 5.5-fold increase in PEA for a microdialysis probe versus a 90 m capillary sampling method was noted. A random walk simulation demonstrated that microdialysis perturbs metabolic processes (Yang et al, 2000a). Amperometric probes are not free from perturbation due to consumption of the analyte; however, the difference in flux consumption is ca.…”

Section: Physiological Host Responsementioning

confidence: 99%

Biosensors for real-time in vivo measurements

Wilson

Gifford

2005

Biosensors and Bioelectronics

592

351

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A Theoretical Description of Microdialysis with Mass Transport Coupled to Chemical Events

Cited by 42 publications

References 23 publications

In vivomonitoring of amine neurotransmitters using microdialysis with on-line capillary electrophoresis

In vivomonitoring of amine neurotransmitters using microdialysis with on-line capillary electrophoresis

Real-time measurement of dopamine fluctuations after cocaine in the brain of behaving rats

Biosensors for real-time in vivo measurements

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