The dataset provides fluorescence images of myocytes in subepicardial myocardium of Langendorff-perfused rat hearts, which were rapidly-frozen (RF) during different contractile state including systole, diastole, and ventricular fibrillation (VF). The RF hearts were subsequently fixed with acetone and paraformaldehyde (PFA) by freeze-substitution procedure, then α-actinin in myocytes of them was immuno-stained with fluorescence labels. As control, hearts rapidly-frozen under mechanical relaxation induced by 2,3-butanedione monoxime (BDM), hearts fixed with PFA solely, hearts rapidly-frozen after PFA-fixation were also prepared.
See details in Tamura et. al. (2025) bioRxiv.
Shoko Tamura, Kentaro Mochizuki, Yasuaki Kumamoto, Yuma Morishita, Masahito Yamanaka, Wen-Jin Ho, Yoshinori Harada, Katsumasa Fujita, Hideo Tanaka (2026) Phase-targeting rapid cryofixation of the beating heart and histological analysis unveil contractile state-dependent sarcomere dynamics., Scientific reports
Published in 2026 Feb 28 (Electronic publication in Feb. 28, 2026, midnight )
(Abstract) The heart is a functional syncytium consisting of numerous cardiomyocytes that repetitively exhibit coordinated contractions/relaxations. However, the extent to which myocyte sarcomere arrangements in the heart differ across beats is unknown. To examine this, we conducted cardiac phase-targeting rapid cryofixation of Langendorff-perfused rat hearts. We adjusted the timepoint of cryogen exposure to the electrically paced heart and observed phase-dependent differences in the sarcomere length (SL) of subepicardial myocytes by alpha-actinin immunohistochemistry, namely a significantly shorter SL during systole than during diastole. We detected spatially inhomogeneous SL distributions by generating a heatmap of the myocardium. For peak systole the SL heatmap exhibited nearly uniform SL shortening within and among the individual myocytes with some myocardia exhibiting nonuniform SLs. During diastole, the heart showed predominant SL elongation, which was also accompanied by patchy distributions of locally short-SL regions, reflecting inhomogeneous SLs. This SL inhomogeneity was attenuated by pharmacological relaxation by 2,3-butanedione monoxime. The heatmap of the rapidly-frozen heart during ventricular fibrillation also revealed inhomogeneous SLs within and among individual myocytes. Overall, cardiac phase-targeting cryofixation unveiled in-depth behaviors on SL in the heart. Our cryofixation strategy will open a new horizon to clarify precise spatiotemporal changes in sarcomere structures and understand cardiac functions.
Tamura, Shoko, Mochizuki, Kentaro, Kumamoto, Yasuaki, Morishita, Yuma, Yamanaka, Masahito, Ho, Wen Jin, Harada, Yoshinori, Fujita, Katsumasa, Tanaka, Hideo (2025/01/01), Phase-targeting rapid cryofixation of the beating heart and histological analysis unveil contractile state-dependent sarcomere dynamics, bioRxiv, 2025.11.15.688585
Published in 2025/01/01
(Abstract) None