Reciprocal regulation of rod and cone synapse by NO (Kourennyi et al 2004)

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Accession:64216
We constructed models of rod and cone photoreceptors using NEURON software to predict how changes in Ca channels would affect the light response in these cells and in postsynaptic horizontal cells.
Reference:
1 . Kourennyi DE, Liu XD, Hart J, Mahmud F, Baldridge WH, Barnes S (2004) Reciprocal modulation of calcium dynamics at rod and cone photoreceptor synapses by nitric oxide. J Neurophysiol 92:477-83 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Neuron or other electrically excitable cell;
Brain Region(s)/Organism:
Cell Type(s): Retina photoreceptor cone GLU cell;
Channel(s): I Chloride; I K; I h; I K,Ca; I Calcium; I Potassium;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s): NO;
Simulation Environment: NEURON;
Model Concept(s): Calcium dynamics; Vision;
Implementer(s): Kourennyi, Dmitri E [dek at case.edu]; Liu, Xiaodong [xliu22 at jhmi.edu];
Search NeuronDB for information about:  Retina photoreceptor cone GLU cell; I Chloride; I K; I h; I K,Ca; I Calcium; I Potassium; NO;
: Cone Photoreceptor Kx h Ca channel

NEURON 
{
	SUFFIX CPR
	
	USEION Ca WRITE iCa VALENCE 2
	USEION Cl WRITE iCl  VALENCE 1
	USEION Kca WRITE iKca VALENCE 1
	
	NONSPECIFIC_CURRENT il, iCGMP
	
	RANGE gCabar, gCa, eCa, SCa, VhalfCa, aoCa
	
             RANGE gClbar,gCl, eCl, SCl
             RANGE gKcabar,gKca, eKca
	
	RANGE gl, el
	RANGE gCGMP, eCGMP
	
	:temporal parameters
	RANGE FactorCaI
	RANGE mCl, Cas
	
	
	

}

UNITS
{
	(mA) = (milliamp)
	(mV) = (millivolt)
	(mS) = (millimho)
	(mol)= (1)
	(M)  = (mol/liter)
	(uM) = (micro M)
}

PARAMETER
{
       
       : Calcium channel 
       gCabar = 4.9 (mS/cm2) <0,1e9>
       eCa =  40 (mV)
       aoCa = 0.0031  (/ms)
       VhalfCa=-16.6 (mV)
       SCa =5.7      (mV)   
   
       
        
       : Cl channel	
       eCl= -45  (mV)
       gClbar = 6.5 (mS/cm2) <0,1e9>
       SCl = 0.09   (uM)                                                     
       Clh = 0.37 (uM)
       FactorCaI = 0.5    
 
       :Ca-dependent K current
       eKca=-80 (mV)
       gKcabar = 0.5 (mS/cm2) 
 
       : leak
        gl=0.01   (mS/cm2)
        el=0 (mV)
	
       : cGMP gated channel	
        gCGMP= 0   (mS/cm2)
	:1.8   (mS/cm2)
        eCGMP=0.8 (mV)
        

}

STATE
{

	nCa
	mKca
	
}

ASSIGNED
{
	v (mV)
	
	iCa (mA/cm2)
	il  (mA/cm2)
             iCl  (mA/cm2)
             iCGMP (mA/cm2) 
             iKca (mA/cm2) 
              
           
           :Ca-dependent potassium channel, Kca
	infmKca
	taumKca  (ms)
	
	infCa
	tauCa  (ms) 
	
	Cas  (uM)
	mCl
	: the paremeter for activation
	
	mKca1
	
	gKca (mho/cm2)
	
	gCa (mho/cm2)
             gCl (mho/cm2)

}

INITIAL
{
	rate(v)
	nCa = infCa
	mKca= infmKca
}




BREAKPOINT
{
	SOLVE states METHOD cnexp
	gCa = (0.001)*gCabar*nCa
	iCa = gCa*(v - eCa)
	
	UNITSOFF
	:if (iCa >= 0) 
	:{
	:	Cas =0
	:}
	:if (iCa < 0) 
	:{
		Cas =-0.2+FactorCaI * (-iCa) * 1 *  0.5         /(1.6e-19)/  (6.023e23) * 1e-6         *1e14    
	:                  mA/cm2 * ms-> n coul/cm2  ->n e /cm2-> nmol/cm2  -> mol /cm2     scale factor
	: all the calculation without consideration of volume
         :    }
                
	
	
	mCl = 1/(1+ exp ( (Clh - Cas)/ SCl  ) ) 
	gCl = (0.001)* gClbar * mCl
	iCl = gCl*(v-eCl)   
	
	mKca1=Cas/(Cas+0.3)
	gKca=(0.001)*gKcabar*mKca*mKca*mKca1
	iKca=gKca*(v-eKca) 
	
	UNITSON
	
	il  = (0.001)*gl*(v-el)
	  
	iCGMP = (0.001)*gCGMP*(v-eCGMP)
	
	
	: the current is in the unit of mA/cm2
	
	
}

DERIVATIVE states
{
	rate(v)
	nCa' = (infCa - nCa)/tauCa
	mKca'= (infmKca - mKca ) /taumKca

}


UNITSOFF


FUNCTION alphamKca(v(mV)) (/ms)
{ 
	alphamKca = (0.001)*15*(80-v)/ ( exp( (80-v)/40 ) -1)
	:alter from orginal settings where it is in the unit of 1/s
}

FUNCTION  betamKca (v(mV)) (/ms)
{
	
	betamKca = (0.001)*20*exp (-v/35)
}



UNITSON


FUNCTION alphaCa(v(mV))(/ms)
{ 
	alphaCa = aoCa*exp( (v - VhalfCa)/(2*SCa)   )
}

FUNCTION betaCa(v(mV))(/ms)
{ 
	betaCa = aoCa*exp( - ( v-VhalfCa)/(2*SCa) )
}


PROCEDURE rate(v (mV))
{
        LOCAL a, b

	
	
	a = alphamKca(v)
	b = betamKca(v)
	taumKca = 1/(a + b)
	infmKca = a/(a + b)
	
	
	
	a = alphaCa(v)
	b = betaCa(v)
	tauCa = 1/(a + b)
	infCa = a/(a + b)

}


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