PUBLICATION

Expression of calcium channel transcripts in the zebrafish heart: dominance of T-type channels

Authors
Haverinen, J., Hassinen, M., Dash, S.N., Vornanen, M.
ID
ZDB-PUB-180510-1
Date
2018
Source
The Journal of experimental biology   221(Pt 10): (Journal)
Registered Authors
Keywords
Adult zebrafish, Calcium channels, Cardiac myocytes, T-type Ca2+ current, Zebrafish heart
MeSH Terms
  • Animals
  • Calcium/metabolism
  • Calcium Channels/genetics
  • Calcium Channels/metabolism*
  • Calcium Channels, T-Type/genetics
  • Calcium Channels, T-Type/metabolism
  • Gene Expression Regulation*
  • Heart Atria/metabolism
  • Heart Ventricles/metabolism
  • Muscle Cells/metabolism
  • Patch-Clamp Techniques
  • Zebrafish/genetics
  • Zebrafish/physiology*
PubMed
29739832 Full text @ J. Exp. Biol.
Abstract
Calcium channels are necessary for cardiac excitation-contraction (E-C) coupling, but Ca2+ channel composition of fish hearts is still largely unknown. To this end, we determined transcript expression of Ca2+ channels in the heart of zebrafish (Danio rerio), a popular model species. Altogether, 18 Ca2+ channel α-subunit genes were expressed in both atrium and ventricle. Transcripts for 7 L-type (Cav1.1a, Cav1.1b, Cav1.2, Cav1.3a, Cav1.3b, Cav1.4a, Cav1.4b), 5 T-type (Cav3.1, Cav3.2a, Cav3.2b, Cav3.3a, Cav3.3b) and 6 P/Q-, N- and R-type (Cav2.1a, Cav2.1b, Cav2.2a, Cav2.2b, Cav2.3a, Cav2.3b) Ca2+ channels were expressed. In the ventricle, T-type channels formed 54.9%, L-type channels 41.1% and P/Q-, N- and R-type channels 4.0% of the Ca2+ channel transcripts. In the atrium, the relative expression of T-type and L-type Ca2+ channel transcripts was 64.1% and 33.8%, respectively (others accounted for 2.1%). Thus, at the transcript level, T-type Ca2+ channels are prevalent in zebrafish atrium and ventricle. At the functional level, peak densities of ventricular T-type (ICaT) and L-type (ICaL) Ca2+ current were 6.3±0.8 and 7.7±0.8 pA pF-1, respectively. ICaT mediated a sizeable sarcolemmal Ca2+ influx into ventricular myocytes: the increment in total cellular Ca2+ content via ICaT was 41.2±7.3 µmol l-1, which was 31.7% of the combined Ca2+ influx (129 µmol l-1) via ICaT and ICaL (88.5±20.5 µmol l-1). The diversity of expressed Ca2+ channel genes in zebrafish heart is high, but dominated by the members of the T-type subfamily. The large ventricular ICaT is likely to play a significant role in E-C coupling.
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