![Figure 3. The effects of luminal Mg2+ on RYR2 open probability, Po (A), opening frequency, Fo (B), and mean open time, τo (C). (A) The membrane potential was −40 mV, which favors the flow of Ca2+ and Mg2+ from luminal to cytoplasmic baths (arrow). Increasing luminal [Ca2+] caused a decrease in channel sensitivity to luminal [Mg2+]. Data points show the mean ± SE, with labels indicating the number of samples (corresponding points in B and C have the same sample numbers). Note that the data in B and C is taken from a subset of channel recordings used in A. This is because not all recordings used in Po measurements were suitable for determining Fo and τo. The parameters derived from fitting Hill curves to the data are listed in Table I. The solid curves show theoretical fits to the data of the luminal-triggered feedthrough model as discussed in Results. The model parameters are listed in Table V.](https://cdn.rupress.org/rup/content_public/journal/jgp/132/4/10.1085_jgp.200810001/7/jgp_200810001_lw_fig3.jpeg?Expires=1773578885&Signature=L3kusrYft~0z7AQMK~stn3MzqqMrAsfyIztc-7gabg6zx2Cv8sG00C8v2IJQznYqgu1TWQ6m66MZPO~8SlPKNuWUxCQBrjwYrWWNtZn6RkJvWLNzr9Pa~g4zKPsoLUJOCDwZvE3g3lYTFdXey5L~PIx2~V8jo~buH6k54kEw7OY1usnCIKHWv6Jtl2xS~4sX-QwLB7rrQlgxC~6O99ggj9KzuCZHsCRNy11T0gK9ydJ5vnbifhkdbfltIHXXtHFebjkQNKNV~Dpo9OQ2z4YBrHFmE7W47Lqfxn4pbyZCDp05-0yvBnIkoubgAvhr2-oYIFurdcO6NsdmNGwcAwka1Q__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
The effects of luminal Mg2+ on RYR2 open probability, Po (A), opening frequency, Fo (B), and mean open time, τo (C). (A) The membrane potential was −40 mV, which favors the flow of Ca2+ and Mg2+ from luminal to cytoplasmic baths (arrow). Increasing luminal [Ca2+] caused a decrease in channel sensitivity to luminal [Mg2+]. Data points show the mean ± SE, with labels indicating the number of samples (corresponding points in B and C have the same sample numbers). Note that the data in B and C is taken from a subset of channel recordings used in A. This is because not all recordings used in Po measurements were suitable for determining Fo and τo. The parameters derived from fitting Hill curves to the data are listed in Table I. The solid curves show theoretical fits to the data of the luminal-triggered feedthrough model as discussed in Results. The model parameters are listed in Table V.
