Fig. 2.

Effects of Mg²⁺/ATP treatment on RyR2 channel gating. a Representative current fluctuations through a single RyR2 channel that demonstrated no increase in P _o after Mg²⁺/ATP treatment. b Mean P _o from experiments where P _o was equivalent or reduced after Mg²⁺/ATP treatment. Mean ± SEM (n = 7). c Representative current fluctuations through a single RyR2 channel where P _o increased after Mg²⁺/ATP treatment. d Mean channel P _o from experiments where P _o increased after Mg²⁺/ATP treatment. Mean ± SEM (n = 10). e Histogram showing the mean channel P _o of all experiments (regardless of whether P _o increased or decreased) in the presence of 50 μM cytosolic Ca²⁺, before and after Mg²⁺/ATP treatment. Open circles show channel P _o for the individual experiments. Mean ± SEM (n = 17, **P < 0.01). f Histogram illustrating the effect of PP1 treatment on RyR2 channels that displayed increased P _o after Mg²⁺/ATP treatment. Control P _o was determined in the presence of 50 μM cytosolic Ca²⁺ alone. The cytosolic face of the channel was then treated for 5 min in the presence of 1 mM ATP and 5 mM Mg²⁺ and washed back to control conditions. The cytosolic face of each channel was then incubated in the presence of a maximum of 12.5 units of PP1, for 10 min, before being washed out to control conditions. Mean ± SD (n = 3)