Science Topics – 169
In striated muscles (cardiac and skeletal muscles), under solution conditions intermediate between contraction and relaxation, the sarcomeres, which are the minimum functional units of contraction, enter an oscillating state (sarcomeric oscillation (SO) state) where they repeatedly contract and relax. There is a tendency to This time, we defined the instantaneous amplitude and phase of both SO, which is the contraction and relaxation of sarcomeres, and the periodic displacement of the Z line that partitions the sarcomere (named sarcosynced oscillation (SSO)), and investigated the breakdown. We have developed a wave analysis method that also captures waveforms as part of the process. We then applied this analysis to skeletal muscle SO that occurs under constant, unchanging calcium concentration conditions. As a result, the interaction between SO and SSO was clearly visualized when the propagating waves generated by sarcomere populations travel in one direction or collide (Figure). It has been found that a "hole" in the instantaneous amplitude accompanied by a sudden jump in the instantaneous phase in SSO can be observed as an indicator characterizing SO (Figure). Even if it is not possible to measure the length of each individual sarcomere, this wave characteristic can be captured by measuring how the striated muscle itself waves. Therefore, this wave characteristic is expected to serve as a basis for evaluating whether the mechanical characteristics of the muscle contraction system of the heart and skeletal muscles inside the human body are normal or abnormal.
Hole behavior captured by analysis of instantaneous amplitude and phase of sarcosynced oscillations reveals wave characteristics of sarcomeric oscillations., Seine A. Shintani, Biochemical and Biophysical Research Communications: 691, 149339, 2023.
＜Figure Legends＞
Interaction between sarcomeric oscillations and Z-line vibrations that partition sarcomeres (sarcocinded oscillations) and their wave characteristics
A. Time-series data of vibrations of 31 consecutive Z-lines of skeletal muscle myofibrils in sarcomeric oscillation state (sarcocinded oscillation)
B. Time series data of sarcomere length change oscillations (sarcomeric oscillations) of 30 consecutive nodes defined as the distance between the Z lines
C. Spatio-temporal distribution of instantaneous amplitude of sarcosynced oscillation
D. Spatiotemporal distribution of instantaneous amplitude of sarcomeric oscillations
E. Spatiotemporal distribution of instantaneous phase of sarcosynced oscillation
F. Spatiotemporal distribution of instantaneous phase of sarcomeric oscillation
G. Changes in the instantaneous amplitude and phase of the sarcosynced oscillation at 4 seconds in the figure. A concavity in the instantaneous amplitude accompanied by a sudden jump in the instantaneous phase that occurs at a distance of 25 μm is an SD hole.
H. Changes in instantaneous amplitude and phase of sarcomeric oscillation at 4 seconds in the figure
Department of Biomedical Sciences, College of Life and Health Sciences, Chubu University