TITLE Calcium ion accumulation without diffusion and buffering NEURON { SUFFIX cabalan USEION ca READ cai, ica WRITE cai RANGE cainit, fCa , icapump,icapumpmax,km } UNITS { (molar) = (1/liter) (mM) = (millimolar) (um) = (micron) (mA) = (milliamp) FARADAY = (faraday) (coulomb) PI = (pi) (1) } PARAMETER { fCa = 0.05 (1) cainit = 0.00002 (mM) dt (ms) celsius = 35 (degC) icapumpmax = 0.00191 (mA/cm2) km = 0.000500 (mM) } ASSIGNED { diam (um) ica (mA/cm2) icapump (mA/cm2) } STATE { cai (mM) <1e-10> } BREAKPOINT { SOLVE state METHOD sparse } INITIAL{ cai=cainit } KINETIC state { icapump = icapumpmax*(1/(1 + km/cai)) COMPARTMENT PI*diam*diam/4 {cai} ~ cai << (-fCa*(ica +icapump)*PI*diam*(1e4)/(2*FARADAY)) }