/* K3132 channel * fills tables with values for alpha and beta and then * uses tweakalpha to alter the values to A and B * values for alpha and beta are taken from: * J. Neurophysiology 82: 2476-2389, 1999 * on page 2478 * * the functions below convert to physiological units to do the * calulations and convert back to SI units for the output */ /* alpha for the type X gate (activation) */ function K13ChanAlphaX(voltage) float voltage = {{voltage} * 1e3 - 0} /* convert to mV, add offset */ float num = {-{0.616 + {0.014 * {voltage}}}} float denom = {{exp {{44 + {voltage}} / {-2.3}}} - 1} /* convert sec to msec */ float act = {{num} / {denom}} * 1e3 return act end /* beta for the type X gate (activation) */ function K13ChanBetaX(voltage) float voltage = {{voltage} * 1e3 - 0} /* convert to mV */ float num = 0.0043 float denom = {exp {{44 + {voltage}} / 34}} /* convert sec to msec */ float act = {{num} / {denom}} * 1e3 return act end function make_K13_channel float Erev = -0.090 /* reversal potential of potassium */ str path = "K13_channel" float xmin = -0.1 /* minimum voltage we will see in the simulation */ float xmax = 0.05 /* maximum voltage we will see in the simulation */ float step = 0.005 /* use a 5mV step size */ int xdivs = 30 /* the number of divisions between -0.1 and 0.05 */ int c = 0 create tabchannel {path} /* make the table for the activation with a range of -100mV - +50mV * with an entry for ever 5mV */ call {path} TABCREATE X {xdivs} {xmin} {xmax} /* set the tau and m_inf for the activation and inactivation */ for(c = 0; c < {xdivs} + 1; c = c + 1) setfield {path} X_A->table[{c}] {K13ChanAlphaX {{c * {step}} + xmin}} setfield {path} X_B->table[{c}] {K13ChanBetaX {{c * {step}} + xmin}} end /* for testing */ // for(c = 0; c < 30; c = c + 1) // showfield {path} X_A->table[{c}] // showfield {path} X_B->table[{c}] // end setfield {path} Ek {Erev} Xpower 4 /* fill the tables with the values of alpha and beta * calculated from tau and m_inf */ tweakalpha {path} X call {path} TABFILL X 3000 0 //setfield {path} X_A->calc_mode 0 X_B->calc_mode 0 end