A model of slow motor unit (Kim, 2017)

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Accession:235769
Cav1.3 channels in motoneuron dendrites are actively involved during normal motor activities. To investigate the effects of the activation of motoneuron Cav1.3 channels on force production, a model motor unit was built based on best-available data. The simulation results suggest that force potentiation induced by Cav1.3 channel activation is strongly modulated not only by firing history of the motoneuron but also by length variation of the muscle as well as neuromodulation inputs from the brainstem.
Reference:
1 . Kim H (2017) Muscle length-dependent contribution of motoneuron Cav1.3 channels to force production in model slow motor unit. J Appl Physiol (1985) 123:88-105 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Neuron or other electrically excitable cell;
Brain Region(s)/Organism:
Cell Type(s): Spinal cord lumbar motor neuron alpha ACh cell; Skeletal muscle cell;
Channel(s): I Calcium; I Potassium; I Sodium; I_AHP;
Gap Junctions:
Receptor(s):
Gene(s): Cav1.3 CACNA1D;
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Active Dendrites;
Implementer(s): Kim, Hojeong [hojeong.kim03 at gmail.com];
Search NeuronDB for information about:  Spinal cord lumbar motor neuron alpha ACh cell; I Sodium; I Calcium; I Potassium; I_AHP;
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Kim2017
fig3
Ca_conc.mod *
CaL.mod *
CaN.mod *
KCa.mod *
KDr.mod *
module1_2.mod *
module3.mod *
mStepIClamp.mod
Naf.mod *
Nap.mod *
Xm.mod *
add_hil_is.hoc *
add_muscle_unit.hoc *
add_pics_istim.hoc
CaL_PICs.hoc *
fig3.ses
fixnseg.hoc *
mem_mechanism_acti.hoc *
mem_mechanism_muscle.hoc *
mem_mechanism_pass.hoc *
motor_unit.hoc
v_e_moto6_export.hoc *
Xm.hoc *
                            
TITLE Persistent Sodium Channel

NEURON {
	SUFFIX Nap
	USEION na READ ena WRITE ina
	RANGE gnapbar, ina, g, i
}

UNITS {
	(mA) = (milliamp)
	(mV) = (millivolt)
	(S)  = (siemens)
}

PARAMETER {
	gnapbar	=0.0008 	(mho/cm2) <0,1e9>
}

ASSIGNED {
	v (mV)
	ena (mv)
	ina (mA/cm2)
	i (mA/cm2)
	g (S/cm2)
	minf mtau
}

STATE {
	m
}

BREAKPOINT {
	SOLVE states METHOD cnexp
	g = gnapbar * m * m * m
	i = g * (v - ena)
	ina = i
}

INITIAL { :Assume v has been constant for a long time
	rates(v)
	m = minf
}

DERIVATIVE states { :Computes state variable m and h at present v & t
	rates(v)
	m' = (minf - m)/mtau
}

PROCEDURE rates(v(mV)) {LOCAL a, b
	a = (-0.0353*(v+21.4))/(exp(-(v+21.4)/5)-1)
	b = (0.000883*(v+25.7))/(exp((v+25.7)/5)-1)
	mtau = 1/(a + b)
	minf = a/(a + b)
}

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