Computer simulations of neuron-glia interactions mediated by ion flux (Somjen et al. 2008)

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Accession:113446
"... To examine the effect of glial K+ uptake, we used a model neuron equipped with Na+, K+, Ca2+ and Cl− conductances, ion pumps and ion exchangers, surrounded by interstitial space and glia. The glial membrane was either “passive”, incorporating only leak channels and an ion exchange pump, or it had rectifying K+ channels. We computed ion fluxes, concentration changes and osmotic volume changes. ... We conclude that voltage gated K+ currents can boost the effectiveness of the glial “potassium buffer” and that this buffer function is important even at moderate or low levels of excitation, but especially so in pathological states."
Reference:
1 . Somjen GG, Kager H, Wadman WJ (2008) Computer simulations of neuron-glia interactions mediated by ion flux. J Comput Neurosci 25:349-65 [PubMed]
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Model Information (Click on a link to find other models with that property)
Model Type: Neuron or other electrically excitable cell; Electrogenic pump; Glia;
Brain Region(s)/Organism:
Cell Type(s): Astrocyte;
Channel(s): I Na,p; I Na,t; I T low threshold; I A; I K; I K,Ca; Na/Ca exchanger; Na/K pump;
Gap Junctions:
Receptor(s): NMDA;
Gene(s):
Transmitter(s): Ions;
Simulation Environment: NEURON;
Model Concept(s): Epilepsy; Calcium dynamics; Sodium pump;
Implementer(s):
Search NeuronDB for information about:  NMDA; I Na,p; I Na,t; I T low threshold; I A; I K; I K,Ca; Na/Ca exchanger; Na/K pump; Ions;
TITLE leak

NEURON {
	SUFFIX leak
	USEION k READ ek WRITE ik
	USEION na READ ena WRITE ina
	USEION cl READ ecl WRITE icl VALENCE -1
	USEION a READ ea WRITE ia VALENCE -1
	RANGE gk, ik, gcl, icl, ga, ia, gna, ina
	RANGE qk, qna, qcl, qa
}

UNITS { 
	(mV) = (millivolt)  (mA) = (milliamp)
	PI		= (pi) (1)
	FARADAY		= 96485.309 (coul)
}

PARAMETER {
	gk	= 1e-5 (mho/cm2)
	gna	= 1e-5 (mho/cm2)
	gcl	= 1e-4 (mho/cm2)
	ga	= 0 (mho/cm2)
}

ASSIGNED {
	v (mV)
	ik (mA/cm2)
	ek (mV)
	ina (mA/cm2)
	ena (mV)
	icl (mA/cm2)
	ecl (mV)
	ia (mA/cm2)
	ea (mV)
	diam (um)
}

BREAKPOINT {
	:SOLVE stromen METHOD after_cvode
	ik = gk*(v-ek)
	ina = gna*(v-ena)
	icl = gcl*(v-ecl)
	ia = ga*(v-ea)
	SOLVE integreer METHOD sparse
}
STATE { qk qna qcl qa }

INITIAL {
	ik = gk*(v-ek)
	ina = gna*(v-ena)
	icl = gcl*(v-ecl)
	ia = ga*(v-ea)
	qk = 0
	qna = 0
	qcl = 0
	qa = 0
}

KINETIC integreer {
	
	COMPARTMENT diam*diam*PI/4 { qna qk qcl qa}
	
	~ qna << ((-ina*diam )*PI*(1e4)/FARADAY )
	~ qk  << (( -ik*diam )*PI*(1e4)/FARADAY )
	~ qcl << ((-icl*diam )*PI*(1e4)/FARADAY )
	~ qa  << (( -ia*diam )*PI*(1e4)/FARADAY )

}

FUNCTION itot(v(mV)) {
	itot=gk*(v-ek)+gna*(v-ena)+gcl*(v-ecl)+ga*(v-ea)
}

PROCEDURE stromen() {
}