SkEIIIK supports minimal Ca²⁺ entry during long global depolarizations. Representative Ca²⁺ transients evoked by global perfusion of 80 mM KCl Ringer's solution for normal myotubes (A), normal myotubes exposed to 100 μM Gd³⁺ (B), normal myotubes exposed to 50 μM nifedipine (C), and dysgenic myotubes expressing SkEIIIK (D). In each case, myotubes were exposed to 200 μM ryanodine for >1 h at 37°C before experiments to block the contribution of RYR1 to the Ca²⁺ transient. In experiments with SkEIIIK, a slower sampling rate was used to minimize any bleaching of the Fluo-3 dye. Expression of SkEIIIK was confirmed by electrically evoked (100 V, 5 ms) contractions (17 of 20 myotubes tested) before ryanodine treatment (see Papadopoulos et al., 2004).