Quantitative determination of acetylcholine in microdialysis samples using liquid chromatography/atmospheric pressure spray ionization mass spectrometry

Keski‐Rahkonen, Pekka; Lehtonen, Marko; Ihalainen, Jouni; Sarajärvi, Timo; Auriola, Seppo

doi:10.1002/rcm.3162

Cited by 42 publications

(53 citation statements)

References 22 publications

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“…The authors improved the method by including the choice of IS, a tetradeuterated analogue (ACh-1,1,2,2-d 4 ), for ACh quantifi cation. The authors considered a deuterated ACh (1,1,2,2-d 4 ) with considerably less incorporation of the stable isotope than the N,N,N-trimethyl-d 9 analog (Keski-Rahkonen et al, 2007) as an IS. In addition, one important feature of isotope dilution quantitative MS analysis has not been considered by the previous (Keski- Rahkonen et al, 2007) implementation of LC-ESI-MS-MS assay for ACh in rat brain microdialysates.…”

Section: Liquid Chromatography Mass Spectrometry Chromatographymentioning

confidence: 99%

“…The major advantage of this method is the ability to monitor ACh in its free form without having to use a cholinesterase inhibitor in the perfusate. Keski-Rahkonen et al (2007) achieved chromatographic separation in 3 min on a reversed-phase column with isocratic conditions using a highly aqueous mobile phase consisting of 0.05% (v/v) of trifl uoro acetic acid as an ion pairing agent. The Prokai et al, 2008 linearity was maintained over the range of 0.15-73 nM, providing a concentration range that is signifi cantly wider than that of the existing LC-MS methods.…”

Section: Liquid Chromatography Mass Spectrometry Chromatographymentioning

confidence: 99%

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Quantification of acetylcholine, an essential neurotransmitter, in brain microdialysis samples by liquid chromatography mass spectrometry

Nirogi

Mudigonda

Kandikere

et al. 2009

Biomedical Chromatography

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Chemical neurotransmission has been the subject of intensive investigations in recent years. Acetylcholine is an essential neurotransmitter in the central nervous system as it has an effect on alertness, memory and learning. Enzymatic hydrolysis of acetylcholine in the synaptic cleft is fast and quickly metabolizes to choline and acetate by acetylcholinesterase. Hence the concentration in the extracellular fluid of the brain is low (0.1-6 nm). Techniques such as microdialysis are routinely employed to measure acetylcholine levels in living brain systems and the microdialysis sample volumes are usually less than 50 microL. In order to develop medicine for the diseases associated with cognitive dysfunction like mild cognitive impairment, Alzheimer's disease, schizophrenia and Parkinson's disease, or to study the mechanism of the illness, it is important to measure the concentration of acetylcholine in the extracellular fluid of the brain. Recently considerable attention has been focused on the development of chromatographic-mass spectrometric techniques to provide more sensitive and accurate quantification of acetylcholine collected from in-vivo brain microdialysis experiments. This review will provide a brief overview of acetylcholine biosynthesis, microdialysis technique and liquid chromatography mass spectrometry, which is being used to quantitate extracellular levels of acetylcholine.

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Section: Liquid Chromatography Mass Spectrometry Chromatographymentioning

confidence: 99%

Section: Liquid Chromatography Mass Spectrometry Chromatographymentioning

confidence: 99%

Quantification of acetylcholine, an essential neurotransmitter, in brain microdialysis samples by liquid chromatography mass spectrometry

Nirogi

Mudigonda

Kandikere

et al. 2009

Biomedical Chromatography

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“…Indeed many recent studies have proposed mechanisms without a consideration of past work or without the use of well-established methods (such as isotopic labeling or theoretical modeling), prompting a recent editorial [1]. A prime example of such mechanistic confusion that can be found in the MS literature is on the important neurotransmitter acetylcholine (ACh), which has been widely studied over several decades using various MS-based approaches [2][3][4][5][6][7][8]. ACh fragments to give two main products: an ion at m/z 87, arising from loss of trimethylamine, and formation of trimethylammonium, Me 3 NH ϩ .…”

mentioning

confidence: 99%

“…These involve: the ester oxygen acting as a neighboring nucleophile to yield the 1-methyl-oxiranium ion, B of Scheme 1 [5,6,8]; intramolecular proton transfer coupled with elimination of trimethylamine to provide 1-(vinyloxy)-ethanol-1-ium, C of Scheme 1 [7]. Thus it is worth considering both of these alternative product ion structures in more detail.…”

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confidence: 99%

How does acetylcholine lose trimethylamine? A density functional theory study of four competing mechanisms

Lioe

Barlow

O’Hair

2009

J. Am. Soc. Mass Spectrom.

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Low-energy collision-induced dissociation (CID) of acetylcholine (ACh) yields only two fragment ions: the dominant C 4 H 7 O 2 ϩ ion at m/z 87, arising from trimethylamine loss; and protonated trimethylamine at m/z 60. Since the literature is replete with conflicting mechanisms for the loss of trimethylamine from ACh, in this article density functional theory (DFT) calculations are used to assess four competing mechanisms: (1) Path A involves a neighboring group attack to form a five-membered ring product, 2-methyl-1,3-dioxolan-2-ylium cation; (2) Path B is a neighboring group attack to form a three-membered ring product, 1-methyloxiranium ion; (3) Path C involves an intramolecular elimination reaction to form C¢O protonated vinylacetate; and (4) Path D is a 1,2-hydride migration reaction forming CH 2 -protonated vinylacetate. At the MP2/6-311ϩϩG(2d,p)//B3-LYP/6-31ϩG(d,p) level of theory path A is the kinetically favored pathway, with a transition-state energy barrier of 37.7 kcal mol Ϫ1 relative to the most stable conformer of ACh. The lowest energy pathway for the formation of protonated trimethylamine was also calculated to proceed via path A, involving proton transfer within the ion-molecule complex intermediate, with the exocylic methyl group being the proton donor. To confirm the site of proton transfer, low-energy CID of acetyl-d 3 -choline (d 3 -ACh) was carried out, which revealed loss of trimethylamine and the formation of Me 3 ND ϩ . (J Am Soc Mass Spectrom 2009, 20, 238 -246)

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“…ACh has been detected by various methods, such as liquid chromatography/electrochemical (LC-EC) method [36][37][38], liquid chromatography/electrospray ionization/ mass spectrometry (LC-ESI-MS) [8,[39][40][41][42], liquid chromatography/atmospheric pressure chemical ionization/mass spectrometry (LC-APCI-MS) [43], as well as MALDI-TOF-MS with CHCA as the matrix [12]. The performances of these methods have been listed in detail on Table 3.…”

Section: Quantitative Methods Validation and Calibration Curvesmentioning

confidence: 99%

High Throughput Enzyme Inhibitor Screening by Functionalized Magnetic Carbonaceous Microspheres and Graphene Oxide-Based MALDI-TOF-MS

Liu

et al. 2011

J. Am. Soc. Mass Spectrom.

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In this work, a high throughput methodology for screening enzyme inhibitors has been demonstrated by combining enzyme immobilized magnetic carbonaceous microspheres and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with grapheme oxide as matrix. First, model enzyme acetylcholinesterase (AChE) was immobilized onto the 3-glycidoxypropyltrimethoxysilane (GLYMO)-modified magnetic carbonaceous (MC) microspheres, displaying a high enzyme activity and stability, and also facilitating the separation of enzyme from substrate and product. The efficiency of immobilized AChE was monitored by biochemical assay, which was carried out by mixing enzyme-immobilized MC microspheres with model substrate acetylcholine (ACh), and subsequent quantitative determination of substrate ACh and product choline using graphene oxide-based MALDI-TOF-MS with no background inference. The limit of detection (LOD) for ACh was 0.25 fmol/μL, and excellent linearity (R 2 =0.9998) was maintained over the range of 0.5 and 250 fmol/μL. Choline was quantified over the range of 0.05 and 15 pmol/μL, also with excellent linearity (R 2 =0.9994) and low LOD (0.15 fmol/μL). Good accuracy and precision were obtained for all concentrations within the range of the standard curves. All together, eight compounds (four known AChE inhibitors and four control chemical compounds with no AChE inhibit effect) were tested with our promoted methodology, and the obtained results demonstrated that our high throughput screening methodology could be a great help to the routine enzyme inhibitor screening.

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Quantitative determination of acetylcholine in microdialysis samples using liquid chromatography/atmospheric pressure spray ionization mass spectrometry

Cited by 42 publications

References 22 publications

Quantification of acetylcholine, an essential neurotransmitter, in brain microdialysis samples by liquid chromatography mass spectrometry

Quantification of acetylcholine, an essential neurotransmitter, in brain microdialysis samples by liquid chromatography mass spectrometry

How does acetylcholine lose trimethylamine? A density functional theory study of four competing mechanisms

High Throughput Enzyme Inhibitor Screening by Functionalized Magnetic Carbonaceous Microspheres and Graphene Oxide-Based MALDI-TOF-MS

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