Figure 3.

Cytosolic [Ca²⁺] in a quiescent half-sarcomere of a fast-twitch CSQ-KO mouse fiber with increasing complexity of the internal and external Ca²⁺ fluxes. Description as in Fig. 2, with an increased RyR1 leak of a factor of 5. Case 4: Ca²⁺ exchange with the extracellular space is kept as in the WT case 3. Case 5 accounts for a greater Ca²⁺ exchange with the extracellular space, representative of the CSQ-KO situation.