The Dmca1D channel mediates Ca²⁺ inward currents in Drosophila embryonic muscles

Abstract

We studied, in a genetic model organism, Drosophila melanogaster, the channel mechanisms underlying membrane excitation in the embryonic body wall muscle whose biophysical properties have been poorly characterized. The inward current underlying the action potential was solely mediated by a high-threshold class of voltage-gated Ca²⁺ channels, which exhibited slow inactivation, Ca²⁺ permeability with saturation at high [Ca²⁺]_OUT, and sensitivity to a Ca²⁺ channel blocker, Cd²⁺. The Ca²⁺ current in the embryonic muscle was completely eliminated in Dmca1D mutants, indicating that the Dmca1D-encoded Ca²⁺ channel is the major mediator of inward currents in the body wall muscles throughout the embryonic and larval stages.

Keywords:

• Ca²⁺ permeability
• Ca²⁺ channel gating
• mutants
• skeletal muscle
• whole-cell patch clamp

Acknowledgements

We thank M. Yoshihara for technical supervision on the electrophysiological experiments, M. Suyama for secretarial assistance, and the Bloomington Stock Center and the Drosophila Genetic Resource Center for fly stocks. This work was supported in part by Grants-in-Aid for Scientific Research (26113702, 26114502, 24113502, and 23220007 to D.Y., and 24570082 and 23115702 to M.K.) from the Japanese Government Ministry of Education, Culture, Sports, Science and Technology (MEXT) to D.Y., the Japan-France Bilateral Joint Research Project Grant from Japan Society for the Promotion of Science (JSPS) to D.Y., a Life Science Grant from the Takeda Science Foundation to D.Y., and a Grant-in-Aid for JSPS fellows (14J07885) to Y.H.

Declaration of interest

The authors report no declarations of interest. The authors alone are responsible for the content and writing of the paper.