Figure 2.

Effect of cooling on the equatorial reflections. (A) Equatorial intensity distributions (perpendicular to the trabecular axis) from one intact trabecula at five temperatures. Magenta, 39°C; orange, 27°C; green, 22°C; cyan, 17°C; blue, 7°C. (B) Corresponding profiles in one demembranated trabecula in the presence of 3% Dextran. Total exposure time, 40 ms. Vertical continuous and dashed lines, position of 1,0 and 1,1 reflections in intact trabecula at 38°C, respectively. (C and D) Spacing of 1,0 reflection (d₁₀) and ratio of equatorial intensities (I₁₁/I₁₀). Gray circles and line, intact trabeculae; empty circles and dashed black line, demembranated trabeculae in the absence of Dextran; black circles and continuous line, demembranated trabeculae in the presence of 3% Dextran. Mean ± SE; n = 5 intact trabeculae and n = 4 demembranated trabeculae. Gray square in C and D, diastolic value in intact trabeculae paced at 1 Hz (T = 26.4°C; data from Brunello et al., 2020); gray diamond in D, peak force value in intact trabeculae (T = 26.4°C; data from Brunello et al., 2020); black diamond in D, maximal calcium activation ([Ca²⁺] = 20 µM; 3% Dextran; T = 27°C; from Brunello et al., 2020). (E and F) Intensity of 1,0 (I₁₀, circles) and 1,1 (I₁₁, triangles) reflections from intact (E; gray symbols) and demembranated trabeculae (F; black symbols, 3% Dextran; white symbols, no Dextran). Mean ± SE; n = 5 intact trabeculae and n = 4 demembranated trabeculae. Data in E normalized by I₁₀ at 39°C; data in F normalized by I₁₀ at 38°C in the presence of Dextran. a.u., arbitrary unit.