kdr.mod

TITLE kdr
: Kalium delayed rectifier
: twee gates met elk twee toestanden
: 
: uit: Traub et al.
: A branching dendritic model of a rodent CA3
: pyramidal neurone.

UNITS {
	(molar) = (1/liter)
	(mV) =	(millivolt)
	(mA) =	(milliamp)
	(mM) =	(millimolar)
}

INDEPENDENT {t FROM 0 TO 1 WITH 100 (ms)}

NEURON {
	SUFFIX kdr
	USEION k READ ek WRITE ik
	RANGE gkbar, gk, ik, qk
	GLOBAL scaletaun, shiftn
}

UNITS {
	:FARADAY	= (faraday) (coulomb)
	FARADAY		= 96485.309 (coul)
	R = (k-mole) (joule/degC)
	PI		= (pi) (1)
}

PARAMETER {
	gkbar=1e-3	(mho/cm2)	: default max. perm.
	scaletaun=1.5
	shiftn=0	(mV)
}

ASSIGNED { 
	ik	(mA/cm2)
	v	(mV)
	ek	(mV)
	dt	(ms)
	gk	(S/cm2)
	diam	(um)
}

STATE { n c qk }

BREAKPOINT {
	SOLVE kstate METHOD sparse
	gk = gkbar*n*n*n*n
	ik = gk*(v-ek)
	:n  = 1 - c
}

INITIAL {
	n=n_inf(v)
	c=1-n
	gk = gkbar*n*n*n*n
	ik = gk*(v-ek)
	qk=0
}

LOCAL a1,a2

KINETIC kstate {
	a1 = a_n(v)
	a2 = a_c(v)
	~ c <-> n	(a1, a2)
	CONSERVE n + c = 1
	COMPARTMENT diam*diam*PI/4 { qk }

	~ qk << (-ik*diam *PI*(1e4)/FARADAY )
}
	
FUNCTION a_n(v(mV)) {
	TABLE DEPEND scaletaun, shiftn FROM -150 TO 150 WITH 200
	a_n = scaletaun*0.016*(35.1-v-shiftn-70)/(exp((35.1-v-shiftn-70)/5)-1)
}

FUNCTION a_c(v(mV)) {
	TABLE DEPEND scaletaun, shiftn FROM -150 TO 150 WITH 200
	a_c = scaletaun*0.25*exp((20-v-shiftn-70)/40)
}

FUNCTION n_inf(v(mV)) {
        n_inf = a_n(v) / ( a_n(v) + a_c(v) )
}

FUNCTION window(v(mV)) {
	window=gkbar*n_inf(v)^4*(v-ek)
}