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. 2010 Nov 22;120(12):4388–4398. doi: 10.1172/JCI32726

Figure 7. Chronic β-adrenergic stimulation causes cardiac dysfunction and remodeling of the RyR2 channel complex.

Figure 7

(A) Echocardiography of left ventricular EF (A) and LVESD (B) in WT mice and RyR2-S2808A+/+ mice during chronic Iso treatment (n = 6 in both groups; mean ± SEM; *P < 0.05 versus WT; #P < 0.05 versus WT baseline). (C) Equivalent amounts of RyR2 were immunoprecipitated with RyR2-specific antibody followed by immunoblotting for relative PKA phosphorylation of RyR2 at Ser2808, oxidation (DNP), and of calstabin2 bound to RyR2. Immunoblotting of PLN- and PKA-phosphorylated PLN was performed on whole heart lysates from WT and RyR2-S2808A+/+ mice. (D and E) Quantification summaries. Mice were continuously treated with Iso for 56 days at a dose of 30 mg/kg/d (WT, n = 3; RyR2-S2808A+/+, n = 3; mean ± SD; *P < 0.05). (F) Aliquots of cardiac lysates from WT mice treated with Iso for 1 or 28 days were incubated at 37°C before the addition of phosphatase inhibitors at the indicated times (top) to stop the RyR2 dephosphorylation reaction. (G) Quantification of RyR2 PKA phosphorylation from F (*P < 0.05). (H) Cardiac RyR2 single-channel activity measured from microsomes from Iso-treated WT and (I) RyR2-S2808A+/+ mice. Channel openings are upward, “C” indicates closed state of the channel, and dotted lines indicate levels of partial openings or subconductance states. Top dash indicates the fully open 4 pA level. The top tracings are condensed time scale (5 s) and the bottom tracings are expanded time scale (500 ms). Amplitude histograms are shown for each channel. To, average open time; Tc, average closed time. (J) Summary of WT (n = 6 channels from 3 mice) and RyR2-S2808A+/+ (n = 8 channels from 3 mice) Po. *P < 0.05.