Ca-dependent K Channel: kinetics from rat muscle (Moczydlowski, Latorre 1983) NEURON

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Accession:3509
Macroscopic channel model based on Moczydlowski, E. and Latorre, R. (1983). Gating kinetics of Ca++ activated K+ channels from rat muscle incorporated into planar lipid bilayers. J. Gen. Physiol. 82: 511-542 See README file for more information.
Reference:
1 . Moczydlowski E, Latorre R (1983) Gating kinetics of Ca2+-activated K+ channels from rat muscle incorporated into planar lipid bilayers. Evidence for two voltage-dependent Ca2+ binding reactions. J Gen Physiol 82:511-42 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Channel/Receptor;
Brain Region(s)/Organism:
Cell Type(s): Skeletal muscle cell;
Channel(s): I K,Ca;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Ion Channel Kinetics;
Implementer(s): Hines, Michael [Michael.Hines at Yale.edu];
Search NeuronDB for information about:  I K,Ca;
/
kca
README
cagk.mod
cagk.hoc
mosinit.hoc
                            
/* cagk.hoc  test of calcium activated potassium channel */
load_file("nrngui.hoc")

// Physical properties
create a
{access a nseg=1 insert cagk}
{cao = 2 diam=10 L=10}

// graphical interface appearance
objref g
g = new Graph(0)
g.view(-80, 0, 180, 0, 10, 300, 300, 200)
strdef s

// simulation control
proc prate() { local v,cai /*plot of cagk channel rate constants*/
	g.erase_all()
	i=0
	g.label(.3,.95,"infcagk & tau vs. V")
	g.label(.8,1,"")
	g.size(-80,100,0,1)
	g.vfixed
	
	//plt(1,100,450) plt(-2) print "infcagk & tau vs. V"
	for (cai=1e-3; cai<1.1e-1; cai=cai*10) {
		i=i+1 g.color(i)
		sprint(s,"cai=%g",cai)
		g.label(s)
		g.beginline
		for (v=-80; v<=100; v = v+1) {
			rate_cagk(v, cai)
			g.line(v,oinf_cagk)
		}
		g.beginline
		for (v=-80; v<=100; v = v+1) {
			rate_cagk(v, cai)
			g.line(v,tau_cagk/10)
		}
	}
	g.flush()
}

proc pcur20() { /*plot potassium current -- used in following proc*/
	g.beginline
	for (v=-80; v<=100; v=v+1) {
		rate_cagk(v,cai)  o_cagk=oinf_cagk
		fcurrent()
		g.line(v,ik)
	}
}

proc pcur2() { /*steady state channel current as function of v and ca*/
	g.erase_all()
	g.color(1)
	g.size(-80,100,0,2)
	g.label(.1,.35,"ik vs V")
	i=0
	g.label(.7,1,"")
	for (cai=1e-3; cai<1.1e-1; cai=cai*10) {
		i=i+1 g.color(i)
		sprint(s,"cai=%g",cai)
		g.label(s) 
		pcur20()
	}
}

proc runvc() { /* cagk current as function of time under voltage clamp*/
	v=-65  t=0  rate_cagk(v,cai)  o_cagk=oinf_cagk /*initialize*/
	fcurrent()
	g.beginline
	while (t < 15) { 
		fadvance()
		g.line(t,ik)
	}
}

proc pvc() { /*voltage clamp of calcium activated potassium channel*/
	g.erase_all()
	dt=.2
	g.size(0,10,0,1)
	g.color(1)
	g.label(.2,.95,"ik vs t  (V = 20 mV)")
	i=0
	g.label(.8,1,"")
	fclamp(2,.5) fclamp(0,10,20) fclamp(1,1e9,-65)
	for (cai=1e-3; cai<1.1e-1; cai=cai*10){
		i=i+1 g.color(i) 
		sprint(s,"cai=%g",cai)
		g.label(s)
		runvc()
	}
	g.flush()
}

proc menu(){
	xpanel("cagk simulations")
	xlabel("Default cagk properties in cagk.mod")
	xlabel("For details see cagk.hoc and cagk.mod")
	xbutton("rate","prate()")
	xbutton("steady state current","pcur2()")
	xbutton("voltage clamp","pvc()")
	xpanel(10,100)
}

// run simulation
menu()

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