Figure 1. Peptide C_c activates RyR2 channels by abbreviating channel closures.

Channel opening (in this and subsequent Figures) is upwards at +40 mV (left-hand panels) and downwards at −40 mV (right-hand panels), from the closed level c to the maximum single channel current o. In (A), control activity is shown with 2 mM MgATP and 100 μM Ca²⁺ in the cis chamber (first trace), after subsequent addition of 100 nM (second trace) or 100 μM peptide (third trace), and shortly after cis perfusion with a solution containing 100 μM Ca²⁺ and lacking MgATP and peptide (fourth trace). Note that the peptide concentration following perfusion is approx. 30 nM and the channel remains activated. Average relative P_o is shown in (B), relative T_os in (C) and relative T_cs in (D) at +40 mV (left-hand panels) and −40 mV (right-hand panels). Means are for five experiments. In (C) to (D), the first symbol and broken line shows data obtained under control conditions.