Figure 5.

Force-velocity measurements with human myocardium. Representative mechanics experiments measuring force-velocity and power. Panels show raw force and raw length traces superposed (top two rows) and force-velocity and force-power curves (bottom two rows) for a single representative preparation measured under control conditions (left column, 0 pN-Bleb) and in the presence of 50 μM pN-Bleb (right column). The symbols showing force, power, and shortening velocity are drawn in the same color as the raw traces from which they were calculated. As described in the Section Methods and by Haynes et al. (2014), these data were obtained by first activating the preparation in pCa 4.5 solution and then allowing it to shorten against loads ranging from 0 to 100% isometric force in successive trials. The shortening velocity was calculated for each trial from the slope of the muscle length against time trace. Similarly, the mean force during shortening was calculated from the force record. Each single trial thus yielded a single data point on the force-velocity plot. Power values were calculated as the product of force and velocity.