TITLE Sodium persistent current for RD Traub et al 2003, 2005
COMMENT
This persistent sodium current is based on the activation
permissive quantity, m, from the transient sodium channel. TMM
modified from an
Implementation by Maciej Lazarewicz 2003 (mlazarew@seas.upenn.edu)
fastNashift init to 0 and removed from arg modification Tom Morse 3/8/2006
(for Traub et al 2005)
The difference between napf and napf_tcr is that napf_tcr has a single power
of m in ina_napf_tcr where as napf has the third power of m in ina_napf
ENDCOMMENT
INDEPENDENT { t FROM 0 TO 1 WITH 1 (ms) }
UNITS {
(mV) = (millivolt)
(mA) = (milliamp)
}
NEURON {
SUFFIX napf_tcr
USEION na READ ena WRITE ina
RANGE gbar, ina,m, df, fastNa_shift, a, b, c, d, minf, mtau
}
PARAMETER {
fastNa_shift = 7 (mV)
a = 0 (1)
b = 0 (1)
c = 0 (1)
d = 0 (1)
gbar = 0.0 (mho/cm2)
v (mV) ena (mV)
}
ASSIGNED {
ina (mA/cm2)
minf (1)
mtau (ms)
df (mV)
}
STATE {
m
}
BREAKPOINT {
SOLVE states METHOD cnexp
ina = gbar * m * ( v  ena )
df = v  ena
}
INITIAL {
settables( v )
m = minf
m = 0
}
DERIVATIVE states {
settables( v )
m' = ( minf  m ) / mtau
}
UNITSOFF
PROCEDURE settables(v1(mV)) {
TABLE minf, mtau FROM 120 TO 40 WITH 641
minf = 1 / ( 1 + exp( (  ( v1 + fastNa_shift )  38 ) / 10 ) )
if( ( v1 + fastNa_shift ) < 30.0 ) {
mtau = 0.025 + 0.14 * exp( ( ( v1 + fastNa_shift ) + 30 ) / 10 )
} else {
mtau = 0.02 + a + (0.145+ b) * exp( (  ( v1 + fastNa_shift +d )  30 ) / (10+c) )
}
}
UNITSON
