Does the Hyperthermal Sarcomeric Oscillations Manifested by Body Temperature Support the Periodic Ventricular Dilation With Each Heartbeat?

Shintani, Seine A.

doi:10.3389/fphys.2022.846206

Cited by 4 publications

(3 citation statements)

References 17 publications

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“…In cardiomyocytes heated to 37°C, conditions are created where the calcium concentration remains high and the sarcomeres are still contracting following the onset of contraction dynamics of EC coupling [ 11 ]. We hypothesize that here, the autonomous sarcomeric oscillation characteristics become evident, actively forming propagating waves as part of the relaxation dynamics [ 4 , 10 , 11 ]. Furthermore, autonomous sarcomere dynamics occur in a fluctuating calcium environment, leading to dynamics associated with sarcomere instability that can be termed ‘EC coupling S4C’ ( Figure 4 ).…”

Section: Discussionmentioning

confidence: 99%

“…In addition, we found that chaotic instability is a common feature of HSOs before and during relaxation of excitation–contraction coupling. We believe that these observations are important for understanding the maintenance of a normal heartbeat and for diagnosis and fundamental treatment of heart disease resulting from a loss of maintenance [ 4 – 6 , 8 , 10 , 17 , 18 ].…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, we discovered that HSOs change their amplitude and phase chaotically to achieve both responsiveness and stability [9]. We hypothesized that the cyclic and rapid relaxation of the ventricular muscle during early diastole, even though the ventricular pressure is low and the intracardiomyocyte calcium concentration remains high, is a consequence of HSOs [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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Observation of sarcomere chaos induced by changes in calcium concentration in cardiomyocytes

Shintani

2024

BIOPHYSICS

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Heating cardiomyocytes to 38–42°C induces hyperthermal sarcomeric oscillations (HSOs), which combine chaotic instability and homeostatic stability. These properties are likely important for achieving periodic and rapid ventricular expansion during the diastole phase of the heartbeat. Compared with spontaneous oscillatory contractions in cardiomyocytes, which are sarcomeric oscillations induced in the presence of a constant calcium concentration, we found that calcium concentration fluctuations cause chaotic instability during HSOs. We believe that the experimental fact that sarcomeres, autonomously oscillating, exhibit such instability due to the action of calcium concentration changes is important for understanding the physiological function of sarcomeres. Therefore, we have named this chaotic sarcomere instability that appears under conditions involving changes in calcium concentration as Sarcomere Chaos with Changes in Calcium Concentration (S4C). Interestingly, sarcomere instability that could be considered S4C has also been observed in the relaxation dynamics of EC coupling. Unlike ADP-SPOCs and Cell-SPOCs under constant calcium concentration conditions, fluctuations in oscillation amplitude indistinguishable from HSOs were observed. Additionally, like HSO, a positive Lyapunov exponent was measured. S4C is likely a crucial sarcomeric property supporting the rapid and flexible ventricular diastole with each heartbeat of the heart.

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