The research result of T-GEx associate Dr. SHINTANI A.Seine, Chubu University, was published in Biochemical and Biophysical Research Communications and a press release was made.
Journal name: Biochemical and Biophysical Research Communications
Paper title: Chaordic Homeodynamics: The Periodic Chaos Phenomenon Observed at the Sarcomere Level and Its Physiological Significance
Author: Seine A. Shintani
DOI: 10.1016/j.bbrc.2025.151712
Key Points of the Announcement
● The sarcomere (Note 1), the smallest contractile unit inside cardiomyocytes, undergoes autonomous high-frequency oscillations (HSOs; Note 2). In the present study we demonstrate—mathematically and statistically, for the first time worldwide—that individual sarcomeres display chaotic fluctuations while the cardiomyocyte as a whole maintains a regular and stable rhythm.
● We propose this phenomenon as a new concept, “Chaordic Homeodynamics” (Note 4): a form of dynamic homeostasis sustained by the coexistence of order (periodicity) and chaos (Note 3) (fluctuations).
Note 1. Sarcomere (muscle sarcomere)
The sarcomere is the smallest contractile unit of muscle. In the presence of Ca²⁺, myosin—one of the main proteins of the myofibril—hydrolyzes adenosine triphosphate (ATP) and pulls actin filaments inward, thereby generating contraction. When the Ca²⁺ concentration falls, actin can no longer bind to myosin, and the muscle relaxes.
Note 2. Autonomous high-frequency oscillations (HSOs: Hyperthermal Sarcomeric Oscillations)
HSOs are self-sustained oscillations in which a sarcomere repeatedly contracts and relaxes without any external stimulus or change in Ca²⁺ concentration. They are triggered when cardiomyocytes are warmed to physiologically hyperthermic temperatures of approximately 38–42 °C. These oscillations arise independently of Ca²⁺ transients and maintain a stable period even when Ca²⁺ fluctuations are present.
Note 3. Chaos
Chaos refers to phenomena that appear disordered and unpredictable but are actually governed by deterministic laws. Minute differences in initial conditions can lead to dramatically different outcomes—a property studied across many scientific disciplines, from weather prediction to biological dynamics.
Note 4. Chaordic Homeodynamics
Chaordic Homeodynamics denotes a form of dynamic homeostasis in which order and chaos coexist. At the level of individual sarcomeres, contraction amplitudes fluctuate chaotically, yet the cell as a whole preserves a regular, stable contraction–relaxation rhythm. This concept captures the flexible regulatory mechanisms that living systems employ to balance robustness with adaptability.
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