TITLE CA1 KM channel from Mala Shah
: M. Migliore June 2006

UNITS {
	(mA) = (milliamp)
	(mV) = (millivolt)
        FARADAY = 96485.332 (coul)
	R = 8.3144626 (joule/K)
        T = 273.15 (K)
	KTOMV = .0853 (mV/K)
}

PARAMETER {
	v 		(mV)
	:ek
	celsius 	(degC)
	gbar=.0001 	(mho/cm2)
        vhalfl=-40   	(mV)
	kl=-10
        vhalft=-42   	(mV)
        a0t=0.003      	(/ms)
        zetat=7    	(1)
        gmt=.4   	(1)
	q10=5
	b0=60
	        ggk
		ko0=5	(mM)
		ki0=150 (mM)
		ko=5	(mM)
		ki=150 (mM)
		nfact =1 (mV)
	st=1
	sh =0
}


NEURON {
	SUFFIX kmb
	USEION k READ ki, ko WRITE ik
        RANGE  gbar,ik, sh, ggk
      GLOBAL inf, tau
}

STATE {
        m
}

ASSIGNED {
	ik (mA/cm2)
        inf
	tau
        taua
	taub
}

INITIAL {
	rate(v)
	nfact=-1000*R*(273.15+celsius)/FARADAY
	ggk=nfact*(log(ki/ko))
	m=inf
}


BREAKPOINT {
	SOLVE state METHOD cnexp
	ggk=nfact*(log(ki/ko))
	ik = gbar*m^st*(v-ggk)
}


FUNCTION alpt(v(mV)) {
  alpt = exp(0.0378*zetat*(v-vhalft-sh)) 
}

FUNCTION bett(v(mV)) {
  bett = exp(0.0378*zetat*gmt*(v-vhalft-sh)) 
}

DERIVATIVE state {
        rate(v)
	m' = (inf - m)/tau
}

PROCEDURE rate(v (mV)) { :callable from hoc
        LOCAL a,qt
        qt=q10^((celsius-35)/10)
        inf = (1/(1 + exp((v-vhalfl-sh)/kl)))
        a = alpt(v)
        tau = b0 + bett(v)/(a0t*(1+a))
}