Assistant Professor Masamine Shintani of Chubu University, in collaboration with Professor Hideo Higuchi of the University of Tokyo Graduate School and Mr. Takumi Washio, Director of the UT-Heart Research Institute, a venture from the University of Tokyo, explains the beating of the heart that periodically contracts and relaxes. Developed a mathematical model that can be done.We elucidated the mechanism by which homeostasis of the heartbeat rhythm is born.
It has been thought that cardiomyocyte contraction and relaxation occur as calcium levels increase and decrease.However, the reason for the seemingly contradictory phenomenon that the heart rapidly relaxes and expands and fills with new blood, although the decrease in calcium concentration in the end-systolic period in cardiomyocytes is slow, was unknown.On the other hand, in 2015, Assistant Professor Shintani and his colleagues discovered a thermal sarcomere vibration phenomenon in which sarcomere vibrates in a cycle that does not match the cycle of increase / decrease in calcium concentration in rat immature cardiomyocytes, which is a type of rat. ..
Thermal sarcomere vibration is the vibration of the sarcomere, which is the smallest unit of contraction, that becomes apparent when cardiomyocytes are warmed to about body temperature.This time, we constructed an experimental system that can measure the sarcomere length in living cardiomyocytes with high precision, investigated the thermal sarcomere vibration in detail, and elucidated the mechanism of vibration based on simulation.As a result, in the isolated cardiomyocytes, the intracellular calcium concentration changed at a low cycle different from the heartbeat frequency, but the thermal sarcomere vibration frequency was the same as the heartbeat frequency.It was discovered that the sarcomere has a mechanism to maintain rhythm homeostasis because the thermal sarcomere vibration greatly changes the amplitude and waveform as the calcium concentration changes, but the cycle is kept constant.
The property that the frequency of thermal sarcomere vibration is close to the heartbeat and the relaxation speed is high is an important property for the heart that has sent blood to the whole body to rapidly relax and expand to fill the blood.This achievement is expected to contribute to the improvement of medical technology such as advance prediction of diastolic heart failure.
Paper information:[Scientific Reports] Mechanism of Contraction RhythmHomeostasis for Hyperthermal Sarcomeric Oscillations of Neonatal Cardiomyocytes
