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.
Otazu
G H
GH
Graduate School of Engineering, Tohoku University, Sendai, Japan. gonzalo@hoshimiya.ecei.tohoku.ac.jp
Futami
R
R
Hoshimiya
N
N
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