A muscle activation model of variable stimulation frequency response and stimulation history, based on positive feedback in calcium dynamics.
Muscle fiber response to a train of variable-frequency pulses includes the potentiation and catch-like effect. For better understanding of these phenomena, we built an activation model with emphasis on the calcium liberation from and re-sequestration into the sarcoplasmic reticulum, including calcium-induced calcium release. The model had two stable equilibrium points in the calcium concentration. Changes from the low to the high equilibrium point could be produced by high-frequency trains of pulses and would account for the potentiation. The model also showed a catch-like effect, as a long-lasting increment of muscle force after the application of a single extra pulse. The increase in force appeared in resting muscle, disappeared when the muscle was potentiated, and reappeared briefly if the stimulation was continued for long periods.
Graduate School of Engineering, Tohoku University, Sendai, Japan. gonzalo@hoshimiya.ecei.tohoku.ac.jp
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Otazu
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Futami
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Hoshimiya
D000200:Action Potentials / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D003198:Computer Simulation; D003491:Cybernetics; D005246:Feedback / Q000502:physiology; D008954:Models, Biological; D009046:Motor Neurons / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000294:innervation / Q000502:physiology; D012519:Sarcoplasmic Reticulum / Q000502:physiology
D002118:Calcium