Electrical stimulation

Living muscles are electrically excitable with contraction being activated by a Ca2+</sub> transient.

FiberSim can create protocol files that include Ca2+</sub> transients generated by a single two compartment model.


The model has two compartments representating the sarcoplasmic reticulum (Ca2+ store) and myofilament space respectively.

The equations defining the model are as follows, where Cax is the Calcium concentration in compartment x.

\[Ca_{SR} + Ca_{myofil} = Ca_{content}\] \[\frac{\mathrm d Ca_{SR}}{\mathrm dt} = \begin{cases} t \leq stimulus\_duration\_s & k_{SERCA} Ca_{myofil} - (k_{leak} + k_{act}) * Ca_{SR} \\ t > stimulus\_duration\_s & k_{SERCA} Ca_{myofil} - k_{leak} * Ca_{SR} \end{cases}\] \[\frac{\mathrm d Ca_{myofil}}{\mathrm dt} = -\frac{\mathrm d Ca_{SR}}{\mathrm dt}\]
Parameter Sets
Ca_content The total Ca2+ (M)
stimulus_duration_s How long Ca2+ from the sarcoplasmic reticulum after a stimulus (s)
k_leak The rate at which Ca2+ leaks from the sarcoplasmic reticulum when there is no stimulus (M s-1)
k_act The additive rate at which Ca2+ is released from the sarcoplasmic reticulum during a stimulus (M s-1)
k_serca The rate at which Ca2+ is pumped back into the sarcoplasmic reticulum (M s-1)

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