Endothelin-1-induced remodelling of murine adult ventricular myocytes. Issue 1 (January 2016)

• Record Type: Journal Article
• Authors: Viero, Cedric; Wegener, Silke; Scholz, Anke; Ruppenthal, Sandra; Tian, Qinghai; Tabellion, Wiebke; Kreinest, Michael; Laschke, Matthias W.; Kaestner, Lars; Lipp, Peter
• Is Part Of: Cell calcium. Volume 59:Issue 1(2016)
• Page Start: 41
• Page End: 53
• Publication Date: 2016-01
• Subjects: Endothelin-1 -- Phenylephrine -- Gq-coupled receptors -- Chronic stimulation -- Ca2+ sparks -- Ca2+ signalling -- Real time quantitative PCR -- Protein kinase C; Calcium -- Metabolism -- Periodicals; Vertebrates -- Physiology -- Periodicals; Calcium -- Physiological effect -- Periodicals; Cell physiology -- Periodicals; Calcium in the body -- Periodicals; 572.516
• DOI: 10.1016/j.ceca.2015.12.005
• Languages: English
• ISSNs: 0143-4160

Abstract

Graphical abstract: Chronic stimulation of rat adult cardiomyocytes with hormones signalling through Gq proteins induces cellular remodelling associated with increased arrhythmogenicity (ECT-extra calcium transients) (A), malfunctional calcium handling (B) and altered gene expression (DIV-days in vitro) (C). Highlights: Chronic (>1 week) Gq stimulation can be mimicked in a single cell model of adult cardiomyocytes. Endothelin-1 and phenylephrine increase cell arrhythmogenicity through genomic regulation. Expression of cardiac PKCγ is regulated by endothelin-1 and phenylephrine stimulation. Chronic endothelin-1 stimulation leads to a desensitization of its inotropic response in vivo . Abstract: The precise role of hormones binding to Gαq protein-coupled receptors (H-Gαq PCRs) in chronic heart diseases remains poorly understood. To address this, we used a model of cultured adult rat ventricular myocytes stimulated with endothelin-1 (ET-1) or phenylephrine (PE) over a period of 8 days in vitro (DIV). Chronically treated cells showed an increased number of arrhythmogenic Ca 2+ transients when electrically paced at 0.5 Hz. While their post-rest behaviour was preserved, from DIV6 onwards the amplitude of caffeine-evoked Ca 2+ transients was increased in hormone-treated cells, suggesting an elevated sarcoplasmic reticulum Ca 2+ load. The duration of electrically evoked global Ca 2+ transients gradually increased over the culturing time indicating decreased activity of processes removing cytosolic Ca 2+ . In treated cells, spontaneous Ca 2+ sparks displayed smaller amplitudes from DIV6 onwards, and a slower decay period for PE (from DIV3) and for ET-1 (from DIV6). This cellular functional remodelling was associated with changes in gene expression: chronic ET-1 treatment decreased PKCγ transcripts, whereas PE increased PKCγ and SERCA2a transcripts as probed by qPCR. Western blot analysis confirmed the upregulation of PKCγ with PE. To study ET-1 receptor desensitization in vivo, osmotic minipumps containing either NaCl or ET-1 were implanted in mice and Ca 2+ signalling was studied in acutely isolated ventricular myocytes after 2 weeks of chronic treatment. Interestingly, while cellular responses to isoproterenol stimulation were preserved in ET-1 treated animals, the inotropic response of myocytes to ET-1 stimulation was abrogated. We therefore conclude that chronic stimulation of cardiac myocytes by H-Gαq PCRs induces cellular remodelling of Ca 2+ cycling with altered PKCγ expression and promotion of arrhythmogenic cellular responses.