Figure 13.

A framework for interpreting tetracaine-dependent changes in Ca_T–Ca_M curves. (A) If withdrawal of tetracaine is accompanied by onset of a Ca²⁺ leak through the RYRs, the steady state Ca_T–Ca_M curve is shifted leftward, as indicated by the arrow. (B) If withdrawal of tetracaine is accompanied by a decrease in $k_{\mathrm{l}\mathrm{e}\mathrm{a}\mathrm{k}}^{\mathrm{T}}$ and no RYR leak, then the Ca_T–Ca_M curve shifts upward if $k_{\mathrm{l}\mathrm{e}\mathrm{a}\mathrm{k}}^{\mathrm{T}}$ decreases (blue dashed curve) or downward if $k_{\mathrm{l}\mathrm{e}\mathrm{a}\mathrm{k}}^{\mathrm{T}}$ increases (blue dotted curve). (C) If withdrawal of tetracaine results in onset of an RYR Ca²⁺ leak and a decrease in $k_{\mathrm{l}\mathrm{e}\mathrm{a}\mathrm{k}}^{\mathrm{T}},$ then the Ca_T–Ca_M curve is shifted leftward and upward.