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Dynamic Homeostasis Driven by
Chaos hidden in the micro‑world of the heart — the secret rhythm that emerges from order and fluctuation
Chaos hidden in the micro‑world of the heart — the secret rhythm that emerges from order and fluctuation
At first glance, the human heart beats with remarkable regularity. Yet at the sub‑cellular level, within each sarcomere (the smallest contractile unit), a far more intricate mechanism is at work. This article explains in detail the phenomenon of heat‑induced sarcomere self‑oscillations (HSOs) discovered by the group led by Seine A. Shintani at Chubu University. When cardiomyocytes are observed at slightly above body temperature (38–42 °C), individual sarcomeres oscillate spontaneously at high speed, and their amplitudes exhibit large, chaotic fluctuations. Strikingly, the entire cell still maintains a stable, periodic contraction–relaxation rhythm, revealing a delicate coexistence of micro‑scale chaos and macro‑scale order.
By measuring sarcomere length with nanometer precision and applying nonlinear analyses such as Lyapunov exponents and recurrence‑plot mapping, the study statistically proves for the first time that this behavior is not random noise but genuine biological chaos intentionally utilized by the cell. The author names this mechanism “Chaordic Homeodynamics,” in which order and chaos coexist to uphold dynamic homeostasis. In other words, the cell intentionally embraces small chaotic fluctuations to remain highly robust and adaptable to environmental changes and stress.
This discovery opens avenues for ultra‑early biomarkers of rhythm disorders and age‑related cardiac disease, and it may inform the design of artificial organs and bio‑inspired engineering. It offers a new biophysical perspective: living systems strategically balance order and chaos to achieve extraordinary adaptability and flexibility.
Figure description
The figure presents multiple analyses of time‑dependent sarcomere length:
(A) Whole‑cell waveform (red) averaged from five sarcomeres, with the low‑frequency component (black), demonstrating sustained periodic beating.
(B) High‑frequency component of a single sarcomere, showing constant period but strongly fluctuating amplitude — evidence of chaotic behavior.
(C) Recurrence plot visualizing the simultaneous presence of periodicity and chaos.
(D) & (E) Statistical analysis of Lyapunov exponents: red dots (original data) are significantly higher than blue and orange randomized data, confirming essential chaos rather than noise.
Article information & citation
Seine A. Shintani. Chaordic Homeodynamics: The periodic chaos phenomenon observed at the sarcomere level and its physiological significance. Biochemical and Biophysical Research Communications, 760, 151712, 2025.
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