title: Endothelin-1-induced remodelling of murine adult ventricular myocytes.
abstract: The precise role of hormones binding to Gαq protein-coupled receptors (H-GαqPCRs) 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-GαqPCRs induces cellular remodelling of Ca(2+) cycling with altered PKCγ expression and promotion of arrhythmogenic cellular responses.
authors.affiliation: Institute for Molecular Cell Biology, School of Medicine, Saarland University, Building 61, 66421 Homburg/Saar, Germany.
authors.forename: Cedric
authors.initials: C
authors.lastname: Viero
authors.affiliation: Institute for Molecular Cell Biology, School of Medicine, Saarland University, Building 61, 66421 Homburg/Saar, Germany.
authors.forename: Silke
authors.initials: S
authors.lastname: Wegener
authors.affiliation: Institute for Molecular Cell Biology, School of Medicine, Saarland University, Building 61, 66421 Homburg/Saar, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Scholz
authors.affiliation: Institute for Molecular Cell Biology, School of Medicine, Saarland University, Building 61, 66421 Homburg/Saar, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Ruppenthal
authors.affiliation: Institute for Molecular Cell Biology, School of Medicine, Saarland University, Building 61, 66421 Homburg/Saar, Germany.
authors.forename: Qinghai
authors.initials: Q
authors.lastname: Tian
authors.affiliation: Institute for Molecular Cell Biology, School of Medicine, Saarland University, Building 61, 66421 Homburg/Saar, Germany.
authors.forename: Wiebke
authors.initials: W
authors.lastname: Tabellion
authors.affiliation: Institute for Molecular Cell Biology, School of Medicine, Saarland University, Building 61, 66421 Homburg/Saar, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Kreinest
authors.affiliation: Institute for Clinical and Experimental Surgery, School of Medicine, Saarland University, Building 65, 66421 Homburg/Saar, Germany.
authors.forename: Matthias W
authors.initials: MW
authors.lastname: Laschke
authors.affiliation: Institute for Molecular Cell Biology, School of Medicine, Saarland University, Building 61, 66421 Homburg/Saar, Germany. Electronic address: lars_kaestner@me.com.
authors.forename: Lars
authors.initials: L
authors.lastname: Kaestner
authors.affiliation: Institute for Molecular Cell Biology, School of Medicine, Saarland University, Building 61, 66421 Homburg/Saar, Germany. Electronic address: peter.lipp@uks.eu.
authors.forename: Peter
authors.initials: P
authors.lastname: Lipp
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D019332:Endothelin-1 / Q000008:administration & dosage*; D015918:Infusion Pumps, Implantable; D008297:Male; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D019332:Endothelin-1; D002118:Calcium
keywords: Ca(2+) signalling; Ca(2+) sparks; Chronic stimulation; Endothelin-1; G(q)-coupled receptors; Phenylephrine; Protein kinase C; Real time quantitative PCR