: Slow delayed rectifier

NEURON {
	SUFFIX sKDR
	USEION k WRITE ik
	RANGE gbar, minf, mtau, i, g, m
	GLOBAL erev
}

UNITS {
	(mA) = (milliamp)
	(mV) = (millivolt)
} 

PARAMETER {
	erev = -85	  (mV)		: effective Ek
	gbar = 0   		(mho/cm2)
 	vmin = -100		(mV)		: for look-up table
	vmax = 100		(mV)
} 


ASSIGNED {
	v 			(mV)
	i 			(mA/cm2)
	ik			(mA/cm2)
	g				(mho/cm2)
	malpha	(/ms)		
	mbeta		(/ms)
	minf
	mtau 		(ms)
}

STATE { m }

INITIAL { 
	rates(v)
	m = minf
}

BREAKPOINT {
  SOLVE states METHOD cnexp
	g = gbar*m^4
	ik = g*(v - erev)
	i = ik
} 

DERIVATIVE states {
	rates(v)
	m' = (minf - m)/mtau
}

PROCEDURE rates(v (mV)) {
TABLE minf, mtau
FROM vmin TO vmax WITH 199
  malpha = 0.028*(v+35)/(1-exp(-0.166*(v+35)))
  mbeta = 0.1056*exp(-0.025*(v+60))
  mtau = 1/(malpha + mbeta)
  minf = malpha/(malpha + mbeta)
}