RyR2-S2030 site phosphorylation level is increased by Iso stimulation. (A) Representative blot showing total RyR2 expression levels in WT (N = 8) and S2030A^+/+ (N = 10) animals. (B) Representative blot showing the level of dephosphorylation at RyR2-S2030 site in WT animals (N = 4), before (C, control) and after 100 nmol/liter Iso application. The numbers 1 and 2 identify different animals. The level of the phosphorylation was expressed as the ratio of the dephospho-RyR2-S2030 and the total RyR ODs, both normalized for the GAPDH signal. Please note that a low level of dephosphorylation corresponds to a high level of phosphorylation. (C) Representative blot showing the maximal level of dephosphorylation at the RyR2-S2030 site in WT animals (N = 4) obtained with a high dose of Iso (1 µmol/liter) combined with the phosphatase inhibitor OA (10 µmol/liter). The dephosphorylation levels were normalized to the control (100%). Iso at the concentration used in all experiments (100 nmol/liter) resulted in a decrease in the signal corresponding to an increased level of phosphorylation (69 ± 6% compared with the control). The combination of high Iso concentration and OA further decreased the signal (44.4 ± 4%). The data are expressed as mean ± SEM of all measurements. *, P < 0.05 versus control; **, P < 0.05, Iso versus OA + Iso.