Effect of voltage sensitive fluorescent proteins on neuronal excitability (Akemann et al. 2009)

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Accession:123453
"Fluorescent protein voltage sensors are recombinant proteins that are designed as genetically encoded cellular probes of membrane potential using mechanisms of voltage-dependent modulation of fluorescence. Several such proteins, including VSFP2.3 and VSFP3.1, were recently reported with reliable function in mammalian cells. ... Expression of these proteins in cell membranes is accompanied by additional dynamic membrane capacitance, ... We used recordings of sensing currents and fluorescence responses of VSFP2.3 and of VSFP3.1 to derive kinetic models of the voltage-dependent signaling of these proteins. Using computational neuron simulations, we quantitatively investigated the perturbing effects of sensing capacitance on the input/output relationship in two central neuron models, a cerebellar Purkinje and a layer 5 pyramidal neuron. ... ". The Purkinje cell model is included in ModelDB.
Reference:
1 . Akemann W, Lundby A, Mutoh H, Knöpfel T (2009) Effect of voltage sensitive fluorescent proteins on neuronal excitability. Biophys J 96:3959-76 [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: Cerebellum;
Cell Type(s): Cerebellum Purkinje GABA cell;
Channel(s): I Na,t; I A; I K; I h; I K,Ca; I Calcium;
Gap Junctions:
Receptor(s):
Gene(s): Kv1.1 KCNA1; Kv4.3 KCND3; Kv3.3 KCNC3; Kv3.4 KCNC4; HCN1;
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s):
Implementer(s): Akemann, Walther [akemann at brain.riken.jp];
Search NeuronDB for information about:  Cerebellum Purkinje GABA cell; I Na,t; I A; I K; I h; I K,Ca; I Calcium;
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
	Loader for a 1-compartment Purkinje cell model
	including recombinant proteins VSFP2.3 and VSFP3.1

	Laboratory for Neuronal Circuit Dynamics
	RIKEN Brain Science Institute, Wako City, Japan
	http://www.neurodynamics.brain.riken.jp

	Date of Implementation: May 2008
	Contact: akemann@brain.riken.jp

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/

celsius = 37  // (degC)

create soma
access soma

soma.nseg = 1
soma.L = 20		// (um)       
soma.diam = 20	// (um)
soma.cm = 1       // (uF/cm2)
soma.Ra = 150	// (ohm cm) 

soma {
insert Nav11
insert Kv1
insert Kv3
insert Kv4
insert KCa1
insert Caint
insert Cav2
insert HCN
insert leak
insert VSFP23M3
insert VSFP31M3
}

gateCurrent_Nav11 = 0
gateCurrent_Kv1 = 0
gateCurrent_Kv3 = 0
gateCurrent_Kv4 = 0
gateCurrent_KCa1 = 0
gateCurrent_Cav2 = 0
gateCurrent_HCN = 0

baseline_VSFP23M3 = 0
baseline_VSFP31M3 = 0

soma.ena = 60	// (mV)
soma.ek = -88	// (mV)
soma.eh_HCN = -30
soma.e_leak = -61
soma.cao = 2   // (mM)
     
soma.gbar_Nav11 = 0.038
soma.gbar_Kv1 = 0.011
soma.gbar_Kv3 = 0.02
soma.gbar_Kv4 = 0.0039
soma.gbar_KCa1 = 2 * 0.007
soma.pbar_Cav2 = 2 * 0.00003
soma.gbar_HCN = 2 * 0.0001
soma.gbar_leak = 0.00012

soma.nc_VSFP23M3 = 0	 // (1/cm2)
soma.nc_VSFP31M3 = 0




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