Skip to main content
. Author manuscript; available in PMC: 2017 Sep 27.
Published in final edited form as: Circulation. 2016 Aug 31;134(13):961–977. doi: 10.1161/CIRCULATIONAHA.116.021618

FIGURE 2. In vivo and isolated cell load dependent parameters in control and cardiac arrest.

FIGURE 2

A. Isolated twitching myocyte before (top) and during twitch in response to electrical activation demonstrating carbon fiber bending. B The sarcomere length (μm) in response to 1 Hz pacing vs time as CF stretch was applied to three different endpoint lengths demonstrates the cellular Frank-Starling effect. Between each step, the CFs were returned to baseline. Each stretch produced increased sarcomere length change. C. Carbon fiber bending (CFB) (proportional to force) vs time demonstrating the increase in both diastolic (passive) and systolic (active) single cell force, respectively. D. Stretch induced peak systolic (open squares) and baseline diastolic (filled squares) tension from a control cell. The linear fits to the data represented the EDLTR (black line) and ESLTR (gray line). In this case, the ESLTR was 22 μN/μm (R2=0.96), and the EDLTR was 6.6 μN/μm (R2=0.95). E. Stretch induced peak systolic (open squares) and baseline diastolic (filled squares) tension from a PMAD cell. In this case, the ESLTR was 11 μN/μm(R2=0.92), and the EDLTR was 6 μN/μm (R2=0.98). F. PRSWcell vs afterloadcell force for control (open squares) and PMAD (filled squares), n= 8 cells from 3 hearts and 8 cells from 2 hearts for control and PMAD, respectively. Exponential fits to the data were done using the equation FSG= y0+A1e(−x/t1). For control and PMAD, respectively, y0, A1, t1 were: 0.94 and 1.47, 9.5 and 2.7, 0.78 s and 0.54 s. R2 were 0.96 and 0.92. N= 8 cells from 3 hearts and 8 cells from 2 hearts for control and PMAD, respectively. G. Force frequency relationship (FFR) for pooled BSF (μm) vs pacing frequency for control (black squares) and PMAD (open squares) plotted with SE, n= 8 cells from 3 hearts and 8 cells from 2 hearts for control and PMAD, respectively. H. Example traces for simultaneous CICR (bottom, gray) and cellular force (top, black) measurements, shown for an isolated cell electrically paced at 1 Hz. The SL was (in μm) ~1.87,~1.94 and ~2.0 (at slack length, first, and second stretch, respectively).