CICR Ca2+ gain. Figure 12: High gain associated with CICR. Voltage clamp protocol used is a 50 ms step pulse to 10 mv from a holding potential of -40 mv. (A) Gain formulation by comparison of Ca2+ flux through the DHP sensitive and RyR sensitive Ca2+ channels. The voltage dependence of gain measured using this method is shown in the inset. (B) Gain formulation by comparison of cytosolic calcium transient formed in the presence and absence of RyR Ca2+ release.