Intrinsic sensory neurons of the gut (Chambers et al. 2014)

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Accession:155796
A conductance base model of intrinsic neurons neurons in the gastrointestinal tract. The model contains all the major voltage-gated and calcium-gated currents observed in these neurons. This model can reproduce physiological observations such as the response to multiple brief depolarizing currents, prolonged depolarizing currents and hyperpolarizing currents. This model can be used to predict how different currents influence the excitability of intrinsic sensory neurons in the gut.
Reference:
1 . Chambers JD, Bornstein JC, Gwynne RM, Koussoulas K, Thomas EA (2014) A detailed, conductance-based computer model of intrinsic sensory neurons of the gastrointestinal tract. Am J Physiol Gastrointest Liver Physiol 307:G517-32 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Neuron or other electrically excitable cell; Channel/Receptor;
Brain Region(s)/Organism:
Cell Type(s): Gastrointestinal tract intrinsic sensory neuron;
Channel(s): I Na,p; I Na,t; I K,leak; I K,Ca; I CAN; I Mixed; I Na, leak; Ca pump;
Gap Junctions:
Receptor(s):
Gene(s): Nav1.3 SCN3A; Nav1.7 SCN9A; Nav1.9 SCN11A SCN12A;
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Detailed Neuronal Models; Action Potentials; Calcium dynamics;
Implementer(s): Chambers, Jordan [jordandchambers at gmail.com];
Search NeuronDB for information about:  I Na,p; I Na,t; I K,leak; I K,Ca; I CAN; I Mixed; I Na, leak; Ca pump;
TITLE Ca-dependent non-specific cation current
: Original model written by Alain Destexhe, Salk Institute, Dec 7, 1992
: Kinetics based on: Partridge & Swandulla, TINS 11: 69-72, 1988.

INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}

NEURON {
	SUFFIX cansc
	USEION other2 WRITE iother2 VALENCE 1
	USEION ca READ cai
        RANGE gbar, i, g, ratc
	GLOBAL m_inf, tau_m, beta, cac, taumin, erev, x
	THREADSAFE m_inf, tau_m, beta, cac, taumin, erev, x
}


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


PARAMETER {
	v		(mV)
	celsius		(degC)
	erev = -38	(mV)
	cai 		(mM)
	gbar	= 4e-4	(mho/cm2)
	beta	= 1e-3	(1/ms)		: backward rate constant
	cac	= 5e-4	(mM)		: middle point of activation fct
	cas	= 2e-5	(mM)		: middle point of activation fct
	taumin	= -0.1	(ms)		: minimal value of time constant
        ratc    = 1e-1
        x       = 2
}


STATE {
	m
}

INITIAL {
:
:  activation kinetics are assumed to be at 22 deg. C
:  Q10 is assumed to be 3
:

	tadj = 3.0 ^ ((celsius-22.0)/10)

	evaluate_fct(v,cai)
	m = m_inf
}

ASSIGNED {
	i	(mA/cm2)
	iother2	(mA/cm2)
	g       (mho/cm2)
	m_inf
	tau_m	(ms)
	tadj
}

BREAKPOINT { 
	SOLVE states METHOD cnexp
	g = gbar * m*m
	i = g * (v - erev)
	iother2 = i
}

DERIVATIVE states { 
	evaluate_fct(v,cai)

	m' = (m_inf - m) / tau_m
}

UNITSOFF

PROCEDURE evaluate_fct(v(mV),cai(mM)) {  LOCAL alpha2:, tcar
  
	alpha2 = ratc/(1+exp((cac-cai)/cas))
 
	tau_m = 1 / (alpha2 + beta) / tadj
	m_inf = alpha2 / (alpha2 + beta)

        if(tau_m < taumin) { tau_m = taumin } 	: min value of time cst
}
UNITSON

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