Distribution of Myosin Attachment Times Predicted from Viscoelastic Mechanics of Striated Muscle

Figure 6

Results of fitting elastic and viscous modulus to gamma distributed and single exponential distributed models of PDF_𝑡att(𝑡). (a, b) The shape parameter, 𝑝, and the scale parameter, 𝛽, were estimated from fitting the gamma distribution model of (16) to the measured elastic and viscous moduli. ^∗𝑃<0.05 by 𝑡-test between MyHC isoforms at same MgATP. (c) The elastic modulus recorded from one PTU 𝛽-MyHC muscle preparation at 1 mM MgATP is shown with its fit to (16), that is, the gamma distribution (GD) model. The goodness of fit is representative of the fits for all samples in this study. The A- and B-processes of (16) were then subtracted from the recorded elastic modulus to demonstrate fluctuations in the remaining C-process, which are more apparent when compared against the single exponential model (𝑝=1) of the 𝑡_att distribution (dotted line). These fluctuations are mechanical consequences of the gamma distributed 𝑡_att. (d) The corresponding viscous modulus was also subjected to fit and subtraction of A- and B-processes. The resulting C-process is compared against the single exponential model of the 𝑡_att distribution (dotted line). The asymmetry in the peak of the viscous modulus is subtle, but apparent at frequencies higher than 11 Hz.