<i>In vivo</i> adenoviral PP1βshRNA significantly augmented the Ca²⁺ transient and % sarcomere shortening in AdV-PP1βshRNA mice cardiomyocytes.

<p>Cardiomyocytes were isolated from the mouse hearts 7 days after gene transfer, followed by an analysis of sarcomere shortening and the Ca²⁺ transient using the Ionoptix system with fura-2 AM dye. Sarcomere length was calculated in a real-time manner using the SarcLen software of the Ionoptix system. <b>A</b>: Representative tracing of sarcomere shortening and Ca²⁺ transient in enzymatically isolated cardiomyocytes from the mouse heart 7 days after adenoviral transfection. <b>B</b>: Summaries of the analysis in sarcomere shortening and Ca²⁺ transients; namely, % sarcomere shortening (%SS), the maximum/minimum value of the first derivatives of sarcomere length (+dL/dt, −dL/dt, respectively), the time constant of the Ca²⁺ transient decay slope (Ca²⁺ transient Tau), and the amplitude of the Ca²⁺ transient (Ca²⁺ transient amplitude). “*” indicates p<0.01 vs. NCshRNA control group. (n = 38 in the NCshRNA group, n = 35 in the PP1βshRNA group). <b>C</b>: Immunoblots of the key SR phosphoproteins and the phospholylation levels 7 days after gene transfer. Note that the phosphorylation levels of PLN at Ser16 was augmented in the PP1βshRNA treated group compared with that of the NCshRNA treated group. <b>D</b>: Summaries of the phospholylation levels of PLN at Ser16 and RyR at 2808 in each group. “*” indicates p<0.05 vs. the NCshRNA treated group. (n = 6 in the NCshRNA group, n = 6 in the PP1βshRNA group).