Figure 5. Tetanic contraction of EDL from WT and JP45/CASQ1 double KO mice.

EDL from wild-type and DKO were first incubated in a Tyrode’s solution containing 1.8 mM CaCl2. Maximal tetanic force was triggered by field stimulation 28 with a train of repetitive pulses (100 Hz of 350 ms duration) at 0.27 Hz. Tetani at 5, 20, 40 and 60s are shown. The same stimulation protocols was applied to muscle which were incubated for 10 min in a bathing solution containing 100 µM La³⁺ (traces WT La³⁺ and DKO La³⁺). The increase the force developed at the end of tetanic stimulation in EDL from KO mice was abolished by 100 mM La³⁺ a blocker of the calcium influx into muscle fibres (compare DKO left panel with middle panel). The effect of La³⁺ was reversed by 10 min long exposure of EDL muscles to a bathing solution containing Ca²⁺ (right panels).