Figure 7.

High speed Ca²⁺ imaging coupled with continuous capacitance measurements reveal a nonlinear increase in Ca²⁺ during responses with superlinear release properties. (A) Fluorescent image of Ctbp2 binding peptide labeled DBs (scale bar 1μm) with schematic in (B) showing regions selected for Ca²⁺ imaging. (C) shows stimulus above, I_Ca response responsible for eliciting the local changes in Ca²⁺ (D) as well as the capacitance changes (E). Expanding the plots from (C–E) in (F–H) focuses on the initial changes in Ca²⁺ current (F), local Ca²⁺ changes (G) and first component of capacitance (H). (I–K) focuses on the onset of the superlinear component again with the Ca²⁺ current (I), local Ca²⁺ signaling (J) and capacitance (K) signals.