optimise Kv3_4.

dbbs_catalogue/mod/Kv3_4.mod

@@ -1,97 +1,98 @@
 : HH TEA-sensitive Purkinje potassium current
 : Created 8/5/02 - nwg
-
 : Suffix from kpkj to Kv3_4
 
 NEURON {
-	SUFFIX Kv3_4
-	USEION k READ ek WRITE ik
-	RANGE gkbar, ik
-	RANGE minf, hinf, mtau, htau
+    SUFFIX Kv3_4
+    USEION k READ ek WRITE ik
+    RANGE gkbar, ik
 }
 
 UNITS {
-	(mV) = (millivolt)
-	(mA) = (milliamp)
+    (mV) = (millivolt)
+    (mA) = (milliamp)
 }
 
 CONSTANT {
-	q10 = 3
+    q10 = 3.0
+    vj  = 11.0 : junction potential
 }
 
 PARAMETER {
-	celsius (degC)
-	v (mV)
-
-	gkbar = .004	(mho/cm2)
-
-	mivh = -24	(mV)
-	mik = 15.4	(1)
-	mty0 = .00012851
-	mtvh1 = 100.7	(mV)
-	mtk1 = 12.9	(1)
-	mtvh2 = -56.0	(mV)
-	mtk2 = -23.1	(1)
-
-	hiy0 = .31
-	hiA = .69
-	hivh = -5.802	(mV)
-	hik = 11.2	(1)
+    celsius             (degC)
+    v                   (mV)
+
+    gkbar   =    0.004	(mho/cm2)
+
+    mivh    =  -24.0    (mV)
+    mik     =   15.4	(1)
+    mty0    =    0.00012851
+    mtvh1   =  100.7	(mV)
+    mtk1    =   12.9    (1)
+    mtvh2   =  -56.0	(mV)
+    mtk2    =  -23.1    (1)
+
+    hiy0    =    0.31
+    hiA     =    0.69
+    hivh    =   -5.802  (mV)
+    hik     =   11.2	(1)
 }
 
-ASSIGNED {
-	minf
-	mtau		(ms)
-	hinf
-	htau		(ms)
-        qt
-}
+ASSIGNED { qt }
 
-STATE {
-	m
-	h
-}
+STATE { m h }
 
 INITIAL {
-	rates(v)
-	m = minf
-	h = hinf
+    LOCAL Vm
+
+    Vm = v + vj
 
-	qt = q10^((celsius-37)/10)
+    m = minf_func(Vm)
+    h = hinf_func(Vm)
+
+    qt = q10^(0.1*(celsius - 37.0))
 }
 
 BREAKPOINT {
-	SOLVE states METHOD cnexp
-	ik = gkbar * m^3 * h * (v - ek)
+    SOLVE states METHOD cnexp
+	LOCAL g
+	g  = gkbar*m*m*m*h
+    ik = g*(v - ek)
 }
 
 DERIVATIVE states {
-	rates(v)
-	m' = (minf - m) / mtau
-	h' = (hinf - h) / htau
-}
+    LOCAL mrho, hrho, minf, hinf, Vm
+
+    Vm = v + vj
+
+    minf = minf_func(Vm)
+    hinf = hinf_func(Vm)
+    mrho = mrho_func(Vm, qt)
+    hrho = hrho_func(Vm, qt)
 
-PROCEDURE rates( Vm (mV)) {
-	LOCAL v_
-	v_ = Vm + 11	: Account for Junction Potential
-	minf = 1/(1+exp(-(v_-mivh)/mik))
-	mtau = (1000) * mtau_func(v_) /qt
-	hinf = hiy0 + hiA/(1+exp((v_-hivh)/hik))
-	htau = 1000 * htau_func(v_) / qt
+    m' = (minf - m)*mrho
+    h' = (hinf - h)*hrho
 }
 
-FUNCTION mtau_func (v (mV)) (ms) {
-	if (v < -35) {
-		mtau_func = (3.4225e-5+.00498*exp(-v/-28.29))*3
-	} else {
-		mtau_func = (mty0 + 1/(exp((v+mtvh1)/mtk1)+exp((v+mtvh2)/mtk2)))
-	}
+FUNCTION minf_func(Vm) { minf_func =        1.0/(1.0 + exp((mivh - Vm)/mik)) }
+FUNCTION hinf_func(Vm) { hinf_func = hiy0 + hiA/(1.0 + exp((Vm - hivh)/hik)) }
+
+FUNCTION mrho_func(Vm, qt) {
+    LOCAL res
+    if (Vm < -35.0) {
+        res = (3.4225e-5 + 0.00498*exp(Vm/28.29))*3.0
+    } else {
+        res = mty0 + 1.0/(exp((Vm + mtvh1)/mtk1) + exp((Vm + mtvh2)/mtk2))
+    }
+    mrho_func = 0.001*qt/res
 }
 
-FUNCTION htau_func(Vm (mV)) (ms) {
-	if ( Vm > 0) {
-		htau_func = .0012+.0023*exp(-.141*Vm)
-	} else {
-		htau_func = 1.2202e-05 + .012 * exp(-((Vm-(-56.3))/49.6)^2)
-	}
+FUNCTION hrho_func(Vm, qt) {
+    LOCAL res
+    if ( Vm > 0) {
+        res = 1.2 + 2.3*exp(-0.141*Vm)
+    } else {
+        res = 0.012202 + 12.0*exp(-((Vm + 56.3)/49.6)^2.0)
+    }
+    hrho_func = qt/res
 }