The firing frequency of spontaneous action potentials and their corresponding evoked exocytosis are increased in chromaffin cells of CCl -induced cirrhotic rats with respect to control rats.

08:00 EDT 22nd October 2018 | BioPortfolio

Summary of "The firing frequency of spontaneous action potentials and their corresponding evoked exocytosis are increased in chromaffin cells of CCl -induced cirrhotic rats with respect to control rats."

High catecolamine plasma levels due to Sympathetic Nervous System (SNS) overactivity contribute to cirrhosis progression. The aim of the present study was to investigate whether chromaffin cells of the adrenal gland might potentiate the deleterious effect exerted by this overactivity. Electrophysiological patch-clamp and amperometric experiments with carbon-fibre electrodes were conducted in single chromaffin cells of control and CCl -induced cirrhotic rats. The spontaneous action potential (sAP) firing frequency was increased in chromaffin cells of cirrhotic rats with respect to control rats. The exocytosis evoked by that firing was also increased. However, exocytosis elicited by ACh did not vary between control and cirrhotic rats. Exocytosis triggered by depolarizing pulses was also unchanged. Amperometric recordings confirmed the lack of increased catecholamine charge released in cirrhosis after ACh or depolarization stimuli. However, the amperometric spikes exhibited faster kinetics of release. The overall Ca entry through voltage-dependent Ca channels (VDCC), or in particular through Cav1 channels, did not vary between chromaffin cells of control and cirrhotic rats. The inhibition of VDCC by methionine-enkephaline or ATP was not either altered, but it was increased by adrenaline in cells of cirrhotic rats. When a cocktail composed by the three neurotransmitters was tested in order to approach a situation closer to the physiological condition, the inhibition of VDCC was similar between both types of cells. In summary, chromaffin cells of the adrenal gland might contribute to exacerbate the SNS overactivity in cirrhosis due to an increased exocytosis elicited by an enhanced spontaneous electrical activity. This article is protected by copyright. All rights reserved.


Journal Details

This article was published in the following journal.

Name: Journal of neurochemistry
ISSN: 1471-4159


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