Fig. 9.

Typical traces of Ca²⁺ transients in the cytosol (A), Ca²⁺ depletions in the SR lumen (B), action potential (AP; C), and Ca²⁺ changes in the cytosol during the AP (D; measured in the presence of 25 μM ryanodine) when a restitution protocol was applied. The concentration of EGTA AM in loading solution was 211 μM. The changes in cytosolic and SR Ca²⁺ concentrations and AP were normalized to the amplitude of the first peak (or nadir in the case of intra-SR Ca²⁺ transients), and the normalized traces were then superimposed. Recordings were conducted at 37°C and at a pacing frequency of 2 Hz.