Table 1. Baseline Mechanical Variables of Papillary Muscles in Adult and Senescent Rats
Values are mean ± SD.
*P < 0.05 vs. adult rats.
Lmax= initial length; CSA = cross-sectional area; RF/TF = ratio of resting force to total force; Vmax= maximum unloaded shortening velocity; maxVc = maximum shortening velocity; AF = isometric active force normalized per CSA; +dF/dt = peak of the positive force derivative normalized per CSA; maxVr = maximum lengthening velocity; −dF/dt = peak of the negative force derivative normalized per CSA; R1 =maxVc/maxVr; R2 = (+dF/dtmax)/ (−dF/dtmax).