Periodicity in Na channel properties alters model neuron excitability (Majumdar and Sikdar 2007)

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"... We have shown earlier that the duration and amplitude of a prolonged depolarization alter all the steady state and kinetic parameters of rNav1.2a voltage gated Na channel in a pseudo-oscillatory fashion. In the present study, we show that the Hodgkin–Huxley voltage and time dependent rate constants of activation (am and bm) and fast inactivation (ah and bh), obtained from the analyses of Na currents and steady state activation and inactivation plots, following application of prepulses in both slow (1–100 s) and fast (100–1000 ms) ranges, vary with the duration of a prepulse in a pseudo-oscillatory manner. ..."
1 . Majumdar S, Sikdar SK (2007) Periodicity in Na+ channel properties alters excitability of a model neuron Biochem Biophys Res Commun.
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):
Channel(s): I Na,t; I K;
Gap Junctions:
Simulation Environment: GENESIS;
Model Concept(s): Ion Channel Kinetics; Epilepsy;
Search NeuronDB for information about:  I Na,t; I K;
This is a graphics file. It is meant for the graphical
representation of the activity of a simple compartment
containing the HH type delayed rectifier potassium 
channel and a transient rat brain sodium channel that 
shows prepulse amplitude and duration dependence. 

// injection to the cell soma

function inject_soma (dialog)
str dialog
setfield /input/injectpulse/somacurr gain {getfield {dialog} value}

//setting the pulsegen object
function make_input

float injwidth = 0.2 //sec
float injdelay = 0.01 //sec
float somacurrent = 2e-9 // injection current to soma

create neutral /input
create pulsegen /input/injectpulse
setfield /input/injectpulse level1 1.0 width1 {injwidth} \ 
delay1 {injdelay} baselevel 0.0 trig_mode 0 delay2 1 
create diffamp /input/injectpulse/somacurr
setfield /input/injectpulse/somacurr saturation 1 gain {somacurrent}
addmsg /input/injectpulse /input/injectpulse/somacurr PLUS output
addmsg /input/injectpulse/somacurr /cell/soma INJECT output


//       RUN STEP

function step_tmax
step {tmax} -time

//  Overlaying graphs

function overlaytoggle (widget)
str widget
setfield /##[TYPE=xgraph] overlay {getfield {widget} state}

// The control panel

function make_control

create xform /control [10,10,350,150]

create xlabel /control/label -label "Control Panel" \
-hgeom 30 -bg cyan

create xbutton /control/RESET -script reset -wgeom 33%\
-ygeom 0:label -offbg yellow

create xbutton /control/RUN -script step_tmax -xgeom 0:RESET \
-ygeom 0:label -wgeom 33% -offbg green

create xbutton /control/QUIT -script quit -xgeom 0:RUN \
-ygeom 0:label -wgeom 33% -offbg red

create xdialog /control/inject -label \
"Current Injection (amperes)" -value 2e-9 \
-script "inject_soma <widget>"

create xtoggle /control/overlay \
-script "overlaytoggle <widget>"
setfield /control/overlay offlabel "Overlay OFF" onlabel \
"Overlay ON" state 0 offfg blue onfg red
xshow /control


//     GRAPHS

function pulse_response
create xform /data
create xform /data/Vm [500,10,400,250]
create xlabel /data/Vm/label -label "Voltage Response" \
-hgeom 30 -bg pink
create xgraph data/Vm/voltage -xmin -0.01 -xmax 0.2 -ymin -0.10 \
-ymax 0.05
setfield ^ XUnits sec YUnits V
addmsg cell/soma /data/Vm/voltage PLOT Vm *soma *red
xshow /data/Vm

create xform /data/Ik [500,500,400,250]
create xlabel /data/Ik/label -label "Current Response" \
-hgeom 30 -bg pink
create xgraph data/Ik/current -xmax 0.2 -ymin -2.0e-9 -ymax 5.0e-10
setfield ^ XUnits sec YUnits A
addmsg cell/soma/Na_rat_sm /data/Ik/current PLOT Ik *Na *blue
addmsg cell/soma/Kdr_hip_traub91 /data/Ik/current PLOT Ik *K *green
xshow /data/Ik

create xform /data/Gk [10,500,400,250]
create xlabel /data/Gk/label -label "Channel Conductances" \
-hgeom 30 -bg pink
create xgraph data/Gk/conductances -xmax 0.2 -ymin 0.1 
setfield ^ XUnits sec YUnits mho
addmsg cell/soma/Na_rat_sm /data/Gk/conductances PLOT Gk *Na *blue
addmsg cell/soma/Kdr_hip_traub91 /data/Gk/conductances PLOT Gk *K *green
xshow /data/Gk


//    Main Script

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