Affiliation:
1. Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland
2. Neuroscience Center and Institute of Biomedicine, Faculty of Medicine, University of Helsinki, P.O. Box 63, 00014 Helsinki, Finland
Abstract
Calcium (Ca) channels are necessary for cardiac excitation-contraction (e-c) coupling, but Ca channel composition of fish hearts is still largely unknown. To this end, we determined transcript expression of Ca channels in the heart of zebrafish (Danio rerio), a popular model species. Altogether 18 Ca 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 Ca channels (Cav2.1a, Cav2.1b, Cav2.2a, Cav2.2b, Cav2.3a, Cav2.3b) were expressed. In the ventricle, T-type channels formed 54.9%, L-type channels 41.1% and P/Q-, N- and R-type Ca channels 4.0% of the Ca channel transcripts. In the atrium, the relative expression of T-type and L-type Ca channel transcripts was 64.1% and 33.8%, respectively (others accounted for 2.1%). Thus, at the transcript level T-type Ca channels are prevalent in zebrafish atrium and ventricle. At the functional level, peak densities of ventricular T-type (ICaT) and L-type (ICaL) Ca current were 6.3±0.8 and 7.7±0.8 pA pF−1, respectively. ICaT mediated a sizeable sarcolemmal Ca influx into ventricular myocyte: increment in total cellular Ca content via ICaT was 41.2±7.3 µmol L−1, which was 31.7% of the combined Ca influx (129 µmol L−1) via ICaT and ICaL (88.5±20.5 µmol L−1). The diversity of expressed Ca 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.
Funder
Jane ja Aatos Erkon Säätiö
Publisher
The Company of Biologists
Subject
Insect Science,Molecular Biology,Animal Science and Zoology,Aquatic Science,Physiology,Ecology, Evolution, Behavior and Systematics
Cited by
24 articles.
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