The bar graphs are organized into two rows, with five graphs in each row. The upper row (A to E) shows parameters at pCa 4, while the lower row (F to J) shows the same parameters at pCa 5.6. Each graph has a y-axis with units and a x-axis labeled with Sex and HFpEF, with categories M and F for sex, and minus and plus for HFpEF status. Panel A and F display steady-state stress in millinewtons per square millimeter. Panel B and G show the rate constant of force development in inverse seconds. Panel C and H depict the duration of the slow phase of relaxation in seconds. Panel D and I illustrate the rate constant of the slow phase of relaxation in inverse seconds. Panel E and J present the rate constant of the fast phase of relaxation in inverse seconds. Each bar represents the mean value with error bars indicating the standard error. Data points are scattered around the bars, representing the average value of one mouse. The graphs compare these parameters across different conditions, showing how they vary with sex and HFpEF status.
XB kinetics at the myofibril level are unchanged in HFpEF-like mice. (A–J) The upper panel (A–E) show cardiac myofibril mechanic parameters at pCa 4, while the lower panels (F–J) show the same parameters at pCa 5.6. Displayed are steady-state stress (A and F), rate constant of force development (B and G), duration of the slow phase of relaxation (C and H), rate constant of the slow phase of relaxation (D and I), and rate constant of the fast phase of relaxation (E and J). The data are presented as means ± SE. The sample sizes include n = 5, 6, 5, and 7 mice, with 3–7 myofibrils analyzed per mouse. Analysis was performed using a linear mixed model with least significant difference post hoc comparisons. Each data point represents the average value of one mouse. kACT, rate constant of force development; TREL,slow, duration of the slow phase of relaxation; kREL,slow, rate constant of the slow phase of relaxation; kREL,fast, rate constant of the fast phase of relaxation.