TTX-R Na+ current effect on cell response (Herzog et al 2001)

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Accession:86537
"Small dorsal root ganglion (DRG) neurons, which include nociceptors, express multiple voltage-gated sodium currents. In addition to a classical fast inactivating tetrodotoxin-sensitive (TTX-S) sodium current, many of these cells express a TTX-resistant (TTX-R) sodium current that activates near -70 mV and is persistent at negative potentials. To investigate the possible contributions of this TTX-R persistent (TTX-RP) current to neuronal excitability, we carried out computer simulations using the Neuron program with TTX-S and -RP currents, fit by the Hodgkin-Huxley model, that closely matched the currents recorded from small DRG neurons. ..." See paper for more and details.
Reference:
1 . Herzog RI, Cummins TR, Waxman SG (2001) Persistent TTX-resistant Na+ current affects resting potential and response to depolarization in simulated spinal sensory neurons. J Neurophysiol 86:1351-64 [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): Dorsal Root Ganglion (DRG) cell;
Channel(s): I Na,p; I Na,t; I K;
Gap Junctions:
Receptor(s):
Gene(s): Nav1.1 SCN1A; Nav1.6 SCN8A; Nav1.7 SCN9A; Nav1.8 SCN10A; Nav1.9 SCN11A SCN12A;
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Ion Channel Kinetics; Nociception;
Implementer(s): Morse, Tom [Tom.Morse at Yale.edu];
Search NeuronDB for information about:  I Na,p; I Na,t; I K;
// fig4.hoc
// fig4 from Herzog et al. 2001

//fig4 A

print "Calculating figure 4.  Please wait."

objref electrode

{soma  electrode = new SEClamp(0.5)}

electrode.rs = 0.01
electrode.dur1 = 10
electrode.amp1 = -120
electrode.dur2 = 200
electrode.amp2 = 40
electrode.dur3 = 50
electrode.amp3 = -120

objref hbox
{hbox = new HBox()}
{hbox.intercept(1)}

objref g[3] // fig 4A, 4B, and 4C

// fig 4A
{g[0] = new Graph()}

electrode.dur2=200
tstop = 220
objref current_vec, time_vec
{current_vec = new Vector()}
{time_vec =  new Vector()}

{current_vec.record(&soma.i_nav1p9(0.5),dt)} // this is the ttx-rp current
{time_vec.record(&t,dt)}

for (test_pulse=-80; test_pulse<=40; test_pulse +=10) {
	electrode.amp2 = test_pulse
	init()
	run()
	{current_vec.line(g[0], time_vec)}
}
{g[0].exec_menu("View = plot")}
{g[0].label(0.6,0.1,"4A")}
print "fig 4A calculated 1/3"

// fig 4B

{g[1] = new Graph()}

electrode.dur2=30
tstop = 50

objref current_vec1
{current_vec1 = new Vector()}

{current_vec1.record(&soma.i_nattxs(0.5),dt)} // ttx-sensitive current
{time_vec.record(&t,dt)}

for (test_pulse=-80; test_pulse<=40; test_pulse +=10) {
	electrode.amp2 = test_pulse
	init()
	run()
	{current_vec1.line(g[1], time_vec)}
}
{g[1].exec_menu("View = plot")}
{g[1].label(0.6,0.1,"4B")}
print "fig 4B calculated 2/3"

// fig 4C

{g[2] = new Graph()}

electrode.dur2=200
tstop = 220

// use previous current_vec's and time

for (test_pulse=-80; test_pulse<=40; test_pulse +=10) {
	electrode.amp2 = test_pulse
	init()
	run()
	{current_vec.add(current_vec1).line(g[2], time_vec)}
}
{g[2].exec_menu("View = plot")}
{g[2].label(0.6,0.1,"4C")}
print "fig 4C calculated 3/3"

{hbox.intercept(0)}
{hbox.map("Fig 4 from Herzog et al. 2001", 240, 220, 600, 450)}

Loading data, please wait...