Nav1.6 sodium channel model in globus pallidus neurons (Mercer et al. 2007)

 Download zip file   Auto-launch 
Help downloading and running models
Accession:105385
Model files for the paper Mercer JN, Chan CS, Tkatch T, Held J, Surmeier DJ. Nav1.6 sodium channels are critical to pacemaking and fast spiking in globus pallidus neurons.,J Neurosci. 2007 Dec 5;27(49):13552-66.
Reference:
1 . Mercer JN, Chan CS, Tkatch T, Held J, Surmeier DJ (2007) Nav1.6 sodium channels are critical to pacemaking and fast spiking in globus pallidus neurons. J Neurosci 27:13552-66 [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): Globus pallidus neuron;
Channel(s): I Na,p; I Na,t; I K; I h; I K,Ca; I Sodium; I Calcium; I Potassium;
Gap Junctions:
Receptor(s):
Gene(s): Nav1.6 SCN8A;
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Action Potential Initiation; Action Potentials; Parkinson's;
Implementer(s): Held, Joshua [j-held at northwestern.edu];
Search NeuronDB for information about:  I Na,p; I Na,t; I K; I h; I K,Ca; I Sodium; I Calcium; I Potassium;
NEURON {
	SUFFIX hcn2_gp
	NONSPECIFIC_CURRENT i
	RANGE i, ehcn, g, gbar
	GLOBAL a0, b0, ah, bh, ac, bc, aa0, ba0
	GLOBAL aa0, ba0, aah, bah, aac, bac
	GLOBAL kon, koff, b, bf, ai, gca, shift
}

UNITS {
	(mV)	= (millivolt)
	(molar)	= (1/liter)
	(mM)	= (millimolar)
	(mA)	= (milliamp)
	(S)	= (siemens)
}

PARAMETER {
	gbar    = 1		(S/cm2)
	ehcn    = -20		(mV)
	a0      = .0009		(/ms)		: parameters for alpha and beta
	b0      = .0004		(/ms)
	ah      = -95		(mV)
	bh      = -51.7		(mV)
	ac      = -.12		(/mV)
	bc      = .12		(/mV)
	aa0     = 3e-05		(/ms)		: parameters for alphaa and betaa
	ba0     = .001		(/ms)
	aah     = -94.2		(mV)
	bah     = -35.5		(mV)
	aac     = -.075		(/mV)
	bac     = .144		(/mV)
	kon     = 30		(/mM-ms)	: cyclic AMP binding parameters
	koff    = 4.5e-05	(/ms)
	b       = 80
	bf      = 8.94
	ai	= 1e-05		(mM)		: concentration cyclic AMP
	gca     = 1				: relative conductance of the bound state
	shift   = -12		(mV)		: shift in voltage dependence
	q10v    = 4				: q10 value from Magee 1998
	q10a    = 1.5				: estimated q10 for the cAMP binding reaction
	celsius			(degC)
}

ASSIGNED {
	v	(mV)
	g	(S/cm2)
	i	(mA/cm2)
	alpha	(/ms)
	beta    (/ms)
	alphaa	(/ms)
	betaa	(/ms)
}

STATE {
	c
	cac
	o
	cao
}

INITIAL {
    SOLVE kin STEADYSTATE sparse
}

BREAKPOINT {
	SOLVE kin METHOD sparse
	g = gbar*(o + cao*gca)
	i = g*(v-ehcn)
}

KINETIC kin {
	LOCAL qa
	qa = q10a^((celsius-22 (degC))/10 (degC))
	rates(v)
	~ c <-> o       (alpha, beta)
	~ c <-> cac     (kon*qa*ai/bf,koff*qa*b/bf)
	~ o <-> cao     (kon*qa*ai, koff*qa)
	~ cac <-> cao   (alphaa, betaa)
	CONSERVE c + cac + o + cao = 1
}

PROCEDURE rates(v(mV)) {
	LOCAL qv	
	qv = q10v^((celsius-22 (degC))/10 (degC))
	if (v > -200) {
		alpha = a0*qv / (1 + exp(-(v-ah-shift)*ac))
		beta = b0*qv / (1 + exp(-(v-bh-shift)*bc))
		alphaa = aa0*qv / (1 + exp(-(v-aah-shift)*aac))
		betaa = ba0*qv / (1 + exp(-(v-bah-shift)*bac))
	} else {
		alpha = a0*qv / (1 + exp(-((-200)-ah-shift)*ac))
		beta = b0*qv / (1 + exp(-((-200)-bh-shift)*bc))
		alphaa = aa0*qv / (1 + exp(-((-200)-aah-shift)*aac))
		betaa = ba0*qv / (1 + exp(-((-200)-bah-shift)*bac))
	}
}

Loading data, please wait...