Simple calcium kinetics

[Tsirogiannis]

Hi.

I m trying to include in a model a simple calcium kinetic scheme in order to calculate the intracellular calcium concentration in each time step. The code of the mod file is like this:

Code: Select all

TITLE CaDiff.mod


COMMENT
Calcium diffusion scheme for Gillies 2005 multi-compartmental STN model
ENDCOMMENT


UNITS {

	(mA) = (milliamp)
	(molar) = (1/liter)
	(mM) = (millimolar)
	(mCb) = (millicoulomb)
}


NEURON {

	SUFFIX CaDiff
	USEION ca READ ica WRITE cai,cao
	RANGE tauCa,cai0,cao0
}


PARAMETER {

	cao0=2 (mM)
	cai0=5E-6 (mM)
	tauCa=0.5e-3 (ms)
	ica (mA/cm2)
	area (micron2)
}

CONSTANT {

	F=9.6485e+4 (mCb/mM)
}

STATE {

	cai (mM) 
	cao (mM)
}


DERIVATIVE state {

	cai'=(1e-11)*(-(1/(2*F))*ica*area)-(cai/tauCa)
	cao'=0
}


INITIAL {

	cai=cai0
	cao=cao0
}


BREAKPOINT {

	SOLVE state METHOD cnexp
}

When I m running the model however, the cai is always the same, equal to the initial value. It's as if the calculation is never done.

Any suggestions?

Thanks a lot in advance

[Raj]

Is area a predefined keyword? If it is not, then you will have to initialize it. If you have to do this from hoc be aware that area(x) returns the area of a segment not a section.