Figure 5.

Effect of cMyBP-C, Pi, and PKA on elastic and viscous moduli measured by stochastic length perturbation analysis at pCa 4.8. Elastic (A and C) and viscous (B and D) moduli plotted against oscillatory frequency for NTG_β and t/t_β mice. Black and green lines indicate 0 and 12 mM Pi conditions, respectively. Solid and dashed lines over the data represent fits to Eq. 2 after AP or PKA treatment, respectively. Vertical lines in B and D indicate the frequencies of the peak viscous moduli and are black for 0 mM Pi, green for 12 mM Pi, solid for AP, and dashed for PKA. Characteristics of the moduli were shifted to higher frequencies with lack of cMyBP-C in the t/t_β, increasing Pi, and PKA treatment. AP, alkaline phosphatase; cMyBP-C, cardiac myosin binding protein-C; NTG_β, nontransgenic; t/t_β, transgenic lacking cMyBP-C; PKA, protein kinase A.