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Machado JD, Montenegro P, Domínguez N. Quantal Release Analysis of Electrochemically Active Molecules Using Single-Cell Amperometry. Methods Mol Biol 2023; 2565:203-211. [PMID: 36205896 DOI: 10.1007/978-1-0716-2671-9_14] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Single-cell amperometry is a powerful technique that permits the detection of electrochemically active transmitters, such as catecholamines, histamine, or serotonin, released by exocytosis from secretory cells.Amperometry has two main characteristics that make it ideal for the study of exocytosis at the single-cell level with single-vesicle resolution quantal release. (i) It is noninvasive. The carbon fiber microelectrode can be carefully positioned on plasma membrane of a single cell, allowing the detection of the oxidation current of the secreted molecules. (ii) High temporal resolution and sensitivity. Exocytosis can be monitored with a real-time resolution that allows the determination of the kinetics release with an attomol detection sensitivity, which ensures an accurate calculation of the amount of transmitter released.Here, we compile some recommendations and advices to perform amperometry quantal analysis.
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Affiliation(s)
- José David Machado
- Dpto. Medicina Física y Farmacología, Facultad de Ciencias de la Salud, Medicina, Universidad de La Laguna, La Laguna, Tenerife, Spain.
| | - Pablo Montenegro
- Pharmacology Unit, Department of Physical Medicine and Pharmacology, Medical School, Universidad de La Laguna, Tenerife, Spain
| | - Natalia Domínguez
- Dpto. Bioquímica, Microbiología, Biología Celular y Genética, Facultad de Ciencias, Sección Biología, Universidad de La Laguna, Tenerife, Spain
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Glucagon-like peptide-1 receptor controls exocytosis in chromaffin cells by increasing full-fusion events. Cell Rep 2021; 36:109609. [PMID: 34433018 DOI: 10.1016/j.celrep.2021.109609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 07/02/2021] [Accepted: 08/04/2021] [Indexed: 11/21/2022] Open
Abstract
Agonists for glucagon-like-peptide-1 receptor (GLP-1R) are currently used for the treatment of type 2 diabetes and obesity. Their benefits have been centered on pancreas and hypothalamus, but their roles in other organ systems are not well understood. We studied the action of GLP-1R on secretions of adrenal medulla. Exendin-4, a synthetic analog of GLP-1, increases the synthesis and the release of catecholamines (CAs) by increasing cyclic AMP (cAMP) production, without apparent participation of cAMP-regulated guanine nucleotide exchange factor (Epac). Exendin-4, when incubated for 24 h, increases CA synthesis by promoting the activation of tyrosine hydroxylase. Short incubation (20 min) increases the quantum size of exocytotic events by switching exocytosis from partial to full fusion. Our results give a strong support to the role of GLP-1 in the fine control of exocytosis.
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González-Santana A, Castañeyra L, Baz-Dávila R, Estévez-Herrera J, Domínguez N, Méndez-López I, Padín JF, Castañeyra A, Machado JD, Ebert SN, Borges R. Adrenergic chromaffin cells are adrenergic even in the absence of epinephrine. J Neurochem 2019; 152:299-314. [PMID: 31677273 DOI: 10.1111/jnc.14904] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 10/24/2019] [Accepted: 10/29/2019] [Indexed: 11/30/2022]
Abstract
Adrenal chromaffin cells release epinephrine (EPI) and norepinephrine (NE) into the bloodstream as part of the homeostatic response to situations like stress. Here we utilized EPI-deficient mice generated by knocking out (KO) the phenylethanolamine N-methyltransferase (Pnmt) gene. These Pnmt-KO mice were bred to homozygosis but displayed no major phenotype. The lack of EPI was partially compensated by an increase in NE, suggesting that EPI storage was optimized in adrenergic cells. Electron microscopy showed that despite the lack of EPI, chromaffin granules retain their shape and general appearance. This indicate that granules from adrenergic or noradrenergic cells preserve their characteristics even though they contain only NE. Acute insulin injection largely reduced the EPI content in wild-type animals, with a minimal reduction in NE, whereas there was only a partial reduction in NE content in Pnmt-KO mice. The analysis of exocytosis by amperometry revealed a reduction in the quantum size (-30%) and Imax (-21%) of granules in KO cells relative to the wild-type granules, indicating a lower affinity of NE for the granule matrix of adrenergic cells. As amperometry cannot distinguish between adrenergic or noradrenergic cells, it would suggest even a larger reduction in the affinity for the matrix. Therefore, our results demonstrate that adrenergic cells retain their structural characteristics despite the almost complete absence of EPI. Furthermore, the chromaffin granule matrix from adrenergic cells is optimized to accumulate EPI, with NE being a poor substitute. Open Science: This manuscript was awarded with the Open Materials Badge For more information see: https://cos.io/our-services/open-science-badges/.
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Affiliation(s)
| | - Leandro Castañeyra
- Unidad de Farmacología, Facultad de Medicina, Universidad de la Laguna, Tenerife, Spain
| | - Rebeca Baz-Dávila
- Unidad de Farmacología, Facultad de Medicina, Universidad de la Laguna, Tenerife, Spain
| | | | - Natalia Domínguez
- INTEGRARE, Généthon, Inserm, Univ Evry, Université Paris-Saclay, Evry, France
| | - Iago Méndez-López
- Instituto Teófilo Hernando, Universidad Autónoma de Madrid, Madrid, Spain
| | - J Fernando Padín
- Instituto Teófilo Hernando, Universidad Autónoma de Madrid, Madrid, Spain.,Departamento Ciencias Médicas (Farmacología), Facultad de Medicina, Universidad de Castilla-La Mancha, Ciudad Real, Spain
| | - Agustín Castañeyra
- Departamento de Ciencias Médicas Básicas, Facultad de Medicina, Universidad de La Laguna, Tenerife, Spain
| | - José-David Machado
- Unidad de Farmacología, Facultad de Medicina, Universidad de la Laguna, Tenerife, Spain
| | - Steven N Ebert
- Division of Metabolic and Cardiovascular Sciences, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Ricardo Borges
- Unidad de Farmacología, Facultad de Medicina, Universidad de la Laguna, Tenerife, Spain
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