Science Topics – 178
How Order and Fluctuations Cooperate to Sustain Cardiac Rhythm.
Our heartbeat is known for its regular, rhythmic pulses that sustain life, but at the microscopic level, the mechanisms behind this rhythm reveal an unexpected interplay between order and chaos. A research group led by Dr. Seine Shintani from Chubu University has discovered that when sarcomeres—the fundamental muscle units in heart cells—are heated, they exhibit self-sustained, high-frequency oscillations (HSOs). Surprisingly, these oscillations include chaotic fluctuations at the individual sarcomere level, yet collectively, the entire cell maintains a highly ordered rhythm. The researchers term this newly uncovered phenomenon "Chaordic Homeodynamics," signifying a dynamic form of homeostasis actively maintained by harnessing small chaotic fluctuations. This groundbreaking insight suggests that cells deliberately utilize controlled chaos to adapt flexibly to changing environmental conditions. The discovery not only deepens our understanding of biological rhythms but also has significant potential implications for the early detection and treatment of heart diseases. Future research into these microscopic fluctuations could unlock novel strategies for medical diagnostics and therapies, offering fresh approaches to managing cardiac health.
Chaordic Homeodynamics: The Periodic Chaos Phenomenon Observed at the Sarcomere Level and Its Physiological Significance., Seine A. Shintani, Biochemical and Biophysical Research Communications: 760, 151712, 2025.
＜Figure Legends＞
Nonlinear Analysis Reveals Chaordic Homeodynamics in Sarcomeric Oscillations
(A) Original waveforms of sarcomere length (SL) from five individual sarcomeres (gray lines), with their averaged waveform (red line) and low-frequency component (black line), demonstrate a globally periodic contraction pattern. (B) A representative high-frequency component (HFC) extracted from a single sarcomere shows constant periodicity, accompanied by large chaotic amplitude fluctuations. (C) The recurrence plot visualizes both periodicity and complexity (chaos) in the oscillation patterns, revealing intricate dynamical structures. (D, E) Lyapunov exponent analysis statistically confirms chaos by showing that the original data (red dots/lines) significantly exceed the values derived from surrogate data sets (blue: AAFT surrogates; orange: FT surrogates), verifying the presence of deterministic chaos rather than random noise.
Department of Biomedical Sciences, College of Life and Health Sciences, Chubu University