A third type of calcium current in cultured human skeletal muscle cells

A third type of calcium current could be recorded on a non-negligible number of human skeletal muscle cells (normal and Duchenne dystrophic (DMD)) in primary culture. This transient current exhibited a maximum at 0 mV, a time-to-peak around 30 ms, an inactivation time constant around 70 ms and was insensitive to nifedipine. On these basis, it differentiates from T- and L-type previously described and looks like the neuronal N-type. However, this third type of current was not sensitive to omega-Cgtx, a specific N-type blocker. The occurrence and the possible role of this current are briefly discussed.