Elimination of dantrolene inhibition by PKA is not reversed by PP1. (A) Representative single-channel recordings of RyR2 that were subjected to in vitro PKA phosphorylation (PP1-PKA, described in Fig. 1) and in vitro dephosphorylation where RyR2s were first subjected to PKA phosphorylation (in the presence of CaMKII inhibitor KN93) and then maximally dephosphorylated by PP1 (PKA-PP1). An untreated sample (neither dephosphorylated nor subsequently phosphorylated, untreated) is included for comparison. Single-channel recording conditions are the same as in Fig. 1, and arrows indicate the addition of 10 μM dantrolene. Channel openings are downward current jumps from the baseline (dashed line). (B) RyR2 Po in the presence of 10 μM dantrolene relative to mean of the bracketing intervals of dantrolene washout are shown for the three incubation conditions above. The dots signify each sample (N represents the number of independent experiments). Data include mean ± SEM for each group. P values denote a significant difference in relative value to 1, which are (left to right) 9 × 10−5, 0.11, and 0.24. (C) Western blot of RyR2s subjected to incubations described in A. Source data are available for this figure: SourceData F2.
Figure 2.

Elimination of dantrolene inhibition by PKA is not reversed by PP1. (A) Representative single-channel recordings of RyR2 that were subjected to in vitro PKA phosphorylation (PP1-PKA, described in Fig. 1) and in vitro dephosphorylation where RyR2s were first subjected to PKA phosphorylation (in the presence of CaMKII inhibitor KN93) and then maximally dephosphorylated by PP1 (PKA-PP1). An untreated sample (neither dephosphorylated nor subsequently phosphorylated, untreated) is included for comparison. Single-channel recording conditions are the same as in Fig. 1, and arrows indicate the addition of 10 μM dantrolene. Channel openings are downward current jumps from the baseline (dashed line). (B) RyR2 Po in the presence of 10 μM dantrolene relative to mean of the bracketing intervals of dantrolene washout are shown for the three incubation conditions above. The dots signify each sample (N represents the number of independent experiments). Data include mean ± SEM for each group. P values denote a significant difference in relative value to 1, which are (left to right) 9 × 10−5, 0.11, and 0.24. (C) Western blot of RyR2s subjected to incubations described in A. Source data are available for this figure: SourceData F2.

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