Figure 5

Depolarization in the absence of external Ca²⁺ eliminates the fast, transient Ca _i ²⁺ and force signals. Intracellular Ca²⁺ (ratio 340/380, blue) and force (red) upon depolarization from 5.9 mM K⁺ to 124 mM K⁺ in the presence of 2.5 mM external Ca²⁺ (124 mM K⁺, A) or after re-addition of 3.5 mM Ca²⁺ to 0Ca (124 K⁺/0-3.5Ca, B). Pair-wise subtraction of 124 mM K⁺/0-3.5Ca from 124 mM K⁺ signals yielded the differential curves for Ca²⁺ (C) and force (D). Results show mean ± s.e.m, n = 4.