| Title: | DEVELOPMENTAL CHANGES OF L-TYPE AND T-TYPE CA2+ CHANNELS IN CARDIAC CELLS |
| DOI No: | 10.1142/9789812702234_0057 |
| Source: | ADVANCES IN ELECTROCARDIOLOGY 2004 (pp 230-238)
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| Author(s): | KENJI YASUI
Department of Circulation, Division of Regulation of Organ Function, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Japan, Hoshigaoka Clinic, Nagoya 464-0026, Japan
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| Abstract: | Regeneration therapy by using bone marrow- or ES cell-derived cells is highlighted for the treatment of failing hearts. These cells have electrophysiological properties similar to embryonic cardiac myocytes. Information available on molecular basis of Ca2+ channels in embryonic hearts is still limited. We investigated the expression of L-type (Cav1.1-1.3) and T-type (Cav3.1-3.2) Ca2+ channels, by a real-time PCR and whole-cell patch clamp in mouse ventricles from an early embryonic stage to adulthood. 1) L-type: At 9.5 dpc, Cav1.1, Cav1.2 and Cav1.3 mRNAs were expressed (Cav1.3 and Cav1.2 were dominant subtypes). With development Cav1.2 increased, Cav1.3 decreased and Cav1.1 became undetectable. Activation and inactivation curves at 9.5 dpc were shifted to the left, compared with those at 18 dpc and adult. 2) T-type: Cav3.2 mRNA was the predominant subtype at both 9.5 dpc and 18 dpc. Cav3.1 mRNA increased with development, but remained low compared with Cav3.2 mRNA. At adult, Cav3.1 is greater than Cav3.2. T-type Ca2+ current was observed only in the embryonic period, and Ni2+ sensitivity suggested that Cav3.2 underlies the functional T-type Ca2+ channels. In conclusions, Cav1.3 and Cav3.2 channels are functionally expressed in early embryonic mouse ventricular cells. Those channels might be responsible for their potent spontaneous activity. |
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