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86 lines
1.5 KiB
86 lines
1.5 KiB
: HH P-type Calcium current |
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: Created 8/13/02 - nwg |
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NEURON { |
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THREADSAFE |
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SUFFIX cap |
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USEION ca READ cai, cao WRITE ica |
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RANGE pcabar, ica |
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RANGE minf, mtau |
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RANGE monovalConc, monovalPerm |
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} |
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UNITS { |
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(mV) = (millivolt) |
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(mA) = (milliamp) |
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(mM) = (milli/liter) |
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F = 9.6485e4 (coul) |
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R = 8.3145 (joule/degC) |
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} |
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PARAMETER { |
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v (mV) |
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celsius (degC) |
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pcabar = 0.00005 (cm/s) |
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monovalConc = 140 (mM) |
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monovalPerm = 0 |
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cai (milli/liter) |
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cao (milli/liter) |
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} |
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ASSIGNED { |
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ica (mA/cm2) |
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minf |
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mtau (ms) |
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T (degC) |
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E (volts) |
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} |
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STATE { |
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m |
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} |
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INITIAL { |
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rates(v) |
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m = minf |
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} |
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BREAKPOINT { |
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SOLVE states METHOD cnexp |
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ica = (1e3) * pcabar * m * ghk(v, cai, cao, 2) |
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} |
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DERIVATIVE states { |
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rates(v) |
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m' = (minf - m)/mtau |
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} |
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FUNCTION ghk( v(mV), ci(mM), co(mM), z) (coul/cm3) { LOCAL Ci |
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T = celsius + 273.19 : Kelvin |
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E = (1e-3) * v |
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Ci = ci + (monovalPerm) * (monovalConc) : Monovalent permeability |
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if (fabs(1-exp(-z*(F*E)/(R*T))) < 1e-6) { : denominator is small -> Taylor series |
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ghk = (1e-6) * z * F * (Ci-co*exp(-z*(F*E)/(R*T)))*(1-(z*(F*E)/(R*T))) |
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} else { |
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ghk = (1e-6) * z^2*(E*F^2)/(R*T)*(Ci-co*exp(-z*(F*E)/(R*T)))/(1-exp(-z*(F*E)/(R*T))) |
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} |
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} |
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PROCEDURE rates (v (mV)) { |
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UNITSOFF |
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minf = 1/(1+exp(-(v - (-19)) / 5.5)) |
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mtau = (mtau_func(v)) * 1e3 |
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UNITSON |
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} |
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FUNCTION mtau_func( v (mV) ) (ms) { |
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UNITSOFF |
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if (v > -50) { |
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mtau_func = .000191 + .00376*exp(-((v-(-41.9))/27.8)^2) |
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} else { |
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mtau_func = .00026367 + .1278 * exp(.10327*v) |
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} |
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UNITSON |
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}
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