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Updated: Jul 27, 2026

Primary Culture of Adult Rat Heart Myocytes
Published on: June 16, 2009
Growth and function of the embryonic heart depend upon the cardiac-specific L-type calcium channel alpha1 subunit
1Department of Medicine, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
Abstract:
The heart must function from the moment of its embryonic assembly, but the molecular underpinnings of the first heart beat are not known, nor whether function determines form at this early stage. Here, we find by positional cloning that the embryonic lethal island beat (isl) mutation in zebrafish disrupts the alpha1 C L-type calcium channel subunit (C-LTCC). The isl atrium is relatively normal in size, and individual cells contract chaotically, in a pattern resembling atrial fibrillation. The ventricle is completely silent. Unlike another mutation with a silent ventricle, isl fails to acquire the normal number of myocytes. Thus, calcium signaling via C-LTCC can regulate heart growth independently of contraction, and plays distinctive roles in fashioning both form and function of the two developing chambers.
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