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Open accessJournal ArticleDOI: 10.1002/CBIC.202000622

Electrochemical Quantification of Neurotransmitters in Single Live Cell Vesicles Shows Exocytosis is Predominantly Partial

02 Mar 2021-ChemBioChem (John Wiley & Sons, Ltd)-Vol. 22, Iss: 5, pp 807-813
Abstract: Exocytosis plays an essential role in the communication between cells in the nervous system. Understanding the regulation of neurotransmitter release during exocytosis and the amount of neurotransmitter content that is stored in vesicles is of importance, as it provides fundamental insights to understand how the brain works and how neurons elicit a certain behavior. In this minireview, we summarize recent progress in amperometric measurements for monitoring exocytosis in single cells and electrochemical cytometry measurements of vesicular neurotransmitter content in individual vesicles. Important steps have increased our understanding of the different mechanisms of exocytosis. Increasing evidence is firmly establishing that partial release is the primary mechanism of release in multiple cell types.

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Topics: Exocytosis (62%)
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Open accessJournal ArticleDOI: 10.1039/D1RA01553B
03 Jun 2021-RSC Advances
Abstract: The development of minimally invasive and easy-to-use sensor devices is of current interest for ultrasensitive detection and signal recognition of Alzheimer's disease (AD) biomarkers. Over the years, tremendous effort has been made on diagnostic platforms specifically targeting neurological markers for AD in order to replace the conventional, laborious, and invasive sampling-based approaches. However, the sophistication of analytical outcomes, marker inaccessibility, and material validity strongly limit the current strategies towards effectively predicting AD. Recently, with the promising progress in biosensor technology, the realization of a clinically applicable sensing platform has become a potential option to enable early diagnosis of AD and other neurodegenerative diseases. In this review, various types of biosensors, which include electrochemical, fluorescent, plasmonic, photoelectrochemical, and field-effect transistor (FET)-based sensor configurations, with better clinical applicability and analytical performance towards AD are highlighted. Moreover, the feasibility of these sensors to achieve point-of-care (POC) diagnosis is also discussed. Furthermore, by grafting nanoscale materials into biosensor architecture, the remarkable enhancement in durability, functionality, and analytical outcome of sensor devices is presented. Finally, future perspectives on further translational and commercialization pathways of clinically driven biosensor devices for AD are discussed and summarized.

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1 Citations


Journal ArticleDOI: 10.1016/J.COELEC.2021.100751
Abstract: In this article, we have summarized the recent important results related to the electrochemical detection of vesicular exocytosis by amperometry with microelectrodes over the past three years. In this fascinating scientific field that began 40 years ago, the historical carbon fiber amperometry method still continues to be used to address biological questions by the pioneered groups of the field but also by other research groups thus showing this has become an indispensable routine technique for analyzing exocytosis. Furthermore, new methodologies (coupling with fluorescence, use of nanoelectrodes, microarrays) have blossomed and demonstrated how new analytical methods could be built to push back the limits of the initial technique.

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1 Citations


Open accessJournal ArticleDOI: 10.1002/ANIE.202108193
07 Aug 2021-Angewandte Chemie
Abstract: Electrochemical methods were used to explore the exocytotic nature of serotonin (5-HT) release in human carcinoid BON cells, an in vitro human enterochromaffin cell model, to understand the mechanisms operating the release of gut-derived 5-HT in the intestinal mucosal epithelium. We show that the fractional vesicular 5-HT release in BON cells is 80 % compared to previous work in pancreatic beta cells (34 %). The fractional release increased from 80 % in control BON cells to 87 % with 5-HT preincubation and nearly 100 % with the combination of 5-HT and the 5-HT4 autoreceptor agonist, cisapride. Thus, partial release is the primary mechanism of exocytosis in BON cells, resulting in a variable amount of the vesicular content being released. Factors that control secretion of 5-HT from enterochromaffin cells or BON cells are important as partial release provides a mechanism for development of effective therapeutic strategies to treat gastrointestinal diseases.

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Topics: Enterochromaffin cell (59%), Exocytosis (52%), Serotonin (50%) ... show more

Journal ArticleDOI: 10.1002/CHEM.202101263
Mengjie Chen1, Si-Min Lu1, Yue-Yi Peng1, Zhifeng Ding2  +1 moreInstitutions (2)
Abstract: The nanoparticle-based electrocatalysts' performance is directly related to their working conditions. In general, a number of nanoparticles are uncontrollably fixed on a millimetre-sized electrode for electrochemical measurements. However, it is hard to reveal the maximum electrocatalytic activity owing to the aggregation and detachment of nanoparticles on the electrode surface. To solve this problem, here, we take the hydrogen evolution reaction (HER) catalyzed by palladium nanoparticles (Pd NPs) as a model system to track the electrocatalytic activity of single Pd NPs by stochastic collision electrochemistry and ensemble electrochemistry, respectively. Compared with the nanoparticle fixed working condition, Pd NPs in the nanoparticle diffused working condition results in a 2-5 orders magnitude enhancement of electrocatalytic activity for HER at various bias potential. Stochastic collision electrochemistry with high temporal resolution gives further insights into the accurate study of NPs' electrocatalytic performance, enabling to dramatically enhance electrocatalytic efficiency.

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46 results found


Open accessJournal ArticleDOI: 10.1113/JPHYSIOL.1954.SP005129
Abstract: In this paper a further study is made of the spontaneous synaptic potentials in frog muscle (Fatt & Katz, 1952a), and their relation to the end-plate response. It has been suggested that the end-plate potential (e.p.p.) at a single nerve-muscle junction is built up statistically of small all-or-none units which are identical in size with the spontaneous 'miniature e.p.p.'s'. The latter, therefore, could be regarded as the least unit, or the 'quantum', of end-plate response. A convenient picture of how hundreds of such quanta, each capable of producing a miniature potential of 0 5-1 0 mV, can build up an e.p.p. of, say, 70-80 mV is provided by the hypothesis that separate parcels of acetylcholine (ACh), released from discrete spots of the nerve endings, short-circuit the muscle membrane. The unit changes of membrane conductance produced at many parallel spots summate and lead to an intense depolarization of the muscle fibre. Although this is a plausible view, there is no direct proof that the normal e.p.p. is made up in this quantal fashion. The evidence comes from experiments in which the 'quantum content' of the e.p.p. had been reduced to a small number by lowering the external calcium concentration (Fatt & Katz, 1952 a). It was then found that the size of the end-plate response approached that of the spontaneous potential and at the same time exhibited large random fluctuations, apparently involving steps of unit size. Similar observations were made by Castillo & Engbaek (1954) on muscles treated with Mg-rich solutions. The statistical behaviour of the end-plate response under these conditions has been investigated in more detail and subjected to a quantitative analysis.

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1,954 Citations


Open accessJournal ArticleDOI: 10.1113/JPHYSIOL.1952.SP004735
Abstract: The present study arose from the chance observation that end-plates of resting muscle fibres are the seat of spontaneous electric discharges which have the character of miniature end-plate potentials. The occurrence of spontaneous subthreshold activity at an apparently normal synapse is of some general interest, and a full description will be given here of observations which have been briefly reported elsewhere (Fatt & Katz, 1950a).

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Topics: Motor nerve (62%), Subthreshold conduction (58%)

1,685 Citations


Journal ArticleDOI: 10.1038/356060A0
Robert H. Chow1, L. von Rueden1, Erwin Neher1Institutions (1)
05 Mar 1992-Nature
Abstract: In synapses, a rise in presynaptic intracellular calcium leads to secretory vesicle fusion in less than a millisecond, as indicated by the short delay from excitation to postsynaptic signal. In nonsynaptic secretory cells, studies at high time resolution have been limited by the lack of a detector as fast and sensitive as the postsynaptic membrane. Electrochemical methods may be sensitive enough to detect catecholamines released from single vesicles. Here, we show that under voltage-clamp conditions, stochastically occurring signals can be recorded from adrenal chromaffin cells using a carbon-fibre electrode as an electrochemical detector. These signals obey statistics characteristic for quantal release; however, in contrast to neuronal transmitter release, secretion occurs with a significant delay after short step depolarizations. Furthermore, we identify a pedestal or 'foot' at the onset of unitary events which may represent the slow leak of catecholamine molecules out of a narrow 'fusion pore' before the pore dilates for complete exocytosis.

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Topics: Secretory Vesicle (57%), Vesicle fusion (57%), Vesicle lumen (56%) ... show more

783 Citations


Journal ArticleDOI: 10.1038/328814A0
L. J. Breckenridge1, Wolfhard Almers1Institutions (1)
01 Aug 1987-Nature
Abstract: Exocytosis, or the fusion of cytoplasmic vesicles with the cell membrane, occurs in nearly all eukaryotic cells, but its mechanism is not understood. Morphological1,2 and electrophysiological studies3–5 have suggested that membrane fusion begins with the formation of a 'fusion pore', a narrow channel across the closely adjacent membranes of vesicle and cell that forms the first connection of the vesicle lumen with the cell exterior and later dilates to allow release of vesicle contents. We used the patch clamp technique to study exocytosis of single giant secretory vesicles in mast cells of beige mice4,5. The first opening of the fusion pore was found to generate a brief current transient, whose size and direction indicated an initial pore conductance of about 230 pS and a lumen-positive vesicle membrane potential. In time-resolved a.c. admittance measurements, the pore conductance was found to increase to much larger values within milliseconds, as if the pore dilated soon after opening. We conclude that the earliest fusion event may be the formation of a structure similar to an ion channel. Its conductance is of the same order of magnitude as that of a single gap junction channel, the only other known channel that spans two membranes.

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Topics: Vesicle fusion (67%), Vesicle lumen (66%), Porosome (65%) ... show more

405 Citations


Open accessJournal ArticleDOI: 10.1016/S0021-9258(18)77173-1
Abstract: Nicotinic receptor-mediated secretion of catecholamines from individual cultured bovine adrenal medullary chromaffin cells was measured and characterized with a voltametric microelectrode placed adjacent to the cells. Nicotine-induced secretion is associated with a large increase in chemical spikes that is temporally resolved into the apparent secretion of discrete packets of attomole quantities of easily oxidized molecules. These data are consistent with direct chemical measurement of single exocytotic events.

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Topics: Chromaffin cell (60%), Adrenal medulla (53%), Exocytosis (53%) ... show more

224 Citations