<?xml version="1.0" encoding="UTF-8"?>
<sbml xmlns="http://www.sbml.org/sbml/level3/version1/core" level="3" version="1">
   <model id="facilitated_ca_diffusion" substanceUnits="substance" 
          areaUnits="area" volumeUnits="litre" timeUnits="second" extentUnits="substance">
       <listOfUnitDefinitions>
           <unitDefinition id="substance">
               <listOfUnits>
                   <unit kind="mole" exponent="1" scale="-6" multiplier="1"/>
               </listOfUnits>
           </unitDefinition>
           <unitDefinition id="area">
               <listOfUnits>
                   <unit kind="metre" exponent="2" scale="-6" multiplier="1"/>
               </listOfUnits>
           </unitDefinition>
           <unitDefinition id="per_second">
               <listOfUnits>
                   <unit kind="second" exponent="-1" scale="0" multiplier="1"/>
               </listOfUnits>
           </unitDefinition>
           <unitDefinition id="litre_per_mole_per_second">
               <listOfUnits>
                   <unit kind="mole"   exponent="-1" scale="-6" multiplier="1"/>
                   <unit kind="litre"  exponent="1"  scale="0"  multiplier="1"/>
                   <unit kind="second" exponent="-1" scale="0"  multiplier="1"/>
               </listOfUnits>
           </unitDefinition>
           <unitDefinition id="subs_per_vol">
               <listOfUnits>
                   <unit kind="mole"  exponent="1"  scale="-6" multiplier="1"/>
                   <unit kind="litre" exponent="-1" scale="0"  multiplier="1"/>
               </listOfUnits>
           </unitDefinition>
       </listOfUnitDefinitions>
       <listOfCompartments>
           <compartment id="Extracellular" 
                        spatialDimensions="3" size="1" constant="true"/>
           <compartment id="PlasmaMembrane" 
                        spatialDimensions="2" size="1"
                        constant="true"/>
           <compartment id="Cytosol" 
                        spatialDimensions="3" size="1"
                        constant="true"/>
       </listOfCompartments>
       <listOfSpecies>
           <species id="CaBPB_C" compartment="Cytosol" initialConcentration="47.17"
                    hasOnlySubstanceUnits="false" boundaryCondition="false"
                    constant="false"/>
           <species id="B_C" compartment="Cytosol" initialConcentration="396.04"
                    hasOnlySubstanceUnits="false" boundaryCondition="false"
                    constant="false"/>
           <species id="CaB_C" compartment="Cytosol" initialConcentration="3.96"
                    hasOnlySubstanceUnits="false" boundaryCondition="false"
                    constant="false"/>
           <species id="Ca_C" name="Ca" compartment="Cytosol" initialConcentration="0.1"
                    hasOnlySubstanceUnits="false" boundaryCondition="false"
                    constant="false"/>
           <species id="Ca_EC" name="Ca" compartment="Extracellular" 
                    initialConcentration="1000"
                    hasOnlySubstanceUnits="false" boundaryCondition="false"
                    constant="false"/>
           <species id="CaCh_PM" compartment="PlasmaMembrane" initialConcentration="1"
                    hasOnlySubstanceUnits="false" boundaryCondition="false"
                    constant="false"/>
           <species id="CaPump_PM" compartment="PlasmaMembrane" initialConcentration="1"
                    hasOnlySubstanceUnits="false" boundaryCondition="false"
                    constant="false"/>
           <species id="CaBP_C" compartment="Cytosol" initialConcentration="202.83"
                    hasOnlySubstanceUnits="false" boundaryCondition="false"
                    constant="false"/>
       </listOfSpecies>
       <listOfReactions>
           <reaction id="CalciumCalbindin_gt_BoundCytosol" reversible="true" fast="true">
               <listOfReactants>
                   <speciesReference species="CaBP_C" stoichiometry="1" constant="true"/>
                   <speciesReference species="Ca_C"   stoichiometry="1" constant="true"/>
               </listOfReactants>
               <listOfProducts>
                   <speciesReference species="CaBPB_C" stoichiometry="1" constant="true"/>
               </listOfProducts>
               <kineticLaw>
                   <notes>
                       <p xmlns="http://www.w3.org/1999/xhtml">
                          (((Kf_CalciumCalbindin_BoundCytosol * CaBP_C) * Ca_C) -
                             (Kr_CalciumCalbindin_BoundCytosol * CaBPB_C))
                       </p>
                   </notes>
                   <math xmlns="http://www.w3.org/1998/Math/MathML">
                       <apply>
                           <times/>
                           <ci> Cytosol </ci>
                           <apply>
                               <minus/>
                               <apply>
                                   <times/>
                                   <ci> Kf_CalciumCalbindin_BoundCytosol </ci>
                                   <ci> CaBP_C </ci>
                                   <ci> Ca_C </ci>
                               </apply>
                               <apply>
                                   <times/>
                                   <ci> Kr_CalciumCalbindin_BoundCytosol </ci>
                                   <ci> CaBPB_C </ci>
                               </apply>
                           </apply>
                       </apply>
                   </math>
                   <listOfLocalParameters>
                       <localParameter id="Kf_CalciumCalbindin_BoundCytosol" value="20.0" 
                                  units="litre_per_mole_per_second"/>
                       <localParameter id="Kr_CalciumCalbindin_BoundCytosol" value="8.6" 
                                  units="per_second"/>
                   </listOfLocalParameters>
               </kineticLaw>
           </reaction>
           <reaction id="CalciumBuffer_gt_BoundCytosol" reversible="true" fast="true">
               <listOfReactants>
                   <speciesReference species="Ca_C" stoichiometry="1" constant="true"/>
                   <speciesReference species="B_C"  stoichiometry="1" constant="true"/>
               </listOfReactants>
               <listOfProducts>
                   <speciesReference species="CaB_C" stoichiometry="1" constant="true"/>
               </listOfProducts>
               <kineticLaw>
                   <notes>
                       <p xmlns="http://www.w3.org/1999/xhtml">
                       (((Kf_CalciumBuffer_BoundCytosol * Ca_C) * B_C) -
                           (Kr_CalciumBuffer_BoundCytosol * CaB_C))
                       </p>
                   </notes>
                   <math xmlns="http://www.w3.org/1998/Math/MathML">
                   <apply>
                       <times/>
                       <ci> Cytosol</ci>
                       <apply>
                           <minus/>
                           <apply>
                               <times/>
                               <ci> Kf_CalciumBuffer_BoundCytosol </ci>
                               <ci> Ca_C </ci>
                               <ci> B_C </ci>
                           </apply>
                           <apply>
                               <times/>
                               <ci> Kr_CalciumBuffer_BoundCytosol </ci>
                               <ci> CaB_C </ci>
                           </apply>
                       </apply>
                   </apply>
                   </math>
                   <listOfLocalParameters>
                       <localParameter id="Kf_CalciumBuffer_BoundCytosol" value="0.1" 
                                  units="litre_per_mole_per_second"/>
                       <localParameter id="Kr_CalciumBuffer_BoundCytosol" value="1.0" 
                                  units="per_second"/>
                   </listOfLocalParameters>
               </kineticLaw>
           </reaction>
           <reaction id="Ca_Pump" reversible="true" fast="false">
               <listOfReactants>
                   <speciesReference species="Ca_C" stoichiometry="1" constant="true"/>
               </listOfReactants>
               <listOfProducts>
                   <speciesReference species="Ca_EC" stoichiometry="1" constant="true"/>
               </listOfProducts>
               <listOfModifiers>
                   <modifierSpeciesReference species="CaPump_PM"/>
               </listOfModifiers>
               <kineticLaw>
                   <notes>
                       <p xmlns="http://www.w3.org/1999/xhtml">
                       ((Vmax * kP * ((Ca_C - Ca_Rest) / (Ca_C + kP)) / 
                           (Ca_Rest + kP)) * CaPump_PM)
                       </p>
                   </notes>
                   <math xmlns="http://www.w3.org/1998/Math/MathML">
                   <apply>
                       <times/>
                       <ci> PlasmaMembrane</ci>
                       <apply>
                           <divide/>
                           <apply>
                               <times/>
                               <ci> Vmax </ci>
                               <ci> kP </ci>
                               <ci> CaPump_PM </ci>
                               <apply>
                                   <minus/>
                                   <ci> Ca_C </ci>
                                   <ci> Ca_Rest </ci>
                               </apply>
                           </apply>
                           <apply>
                               <times/>
                               <apply>
                                   <plus/>
                                   <ci> Ca_C </ci>
                                   <ci> kP </ci>
                               </apply>
                               <apply>
                                   <plus/>
                                   <ci> Ca_Rest </ci>
                                   <ci> kP </ci>
                               </apply>
                           </apply>
                       </apply>
                   </apply>
                   </math>
                   <listOfLocalParameters>
                       <localParameter id="Vmax" value="4000" units="per_second"/>
                       <localParameter id="kP" value="0.25" units="subs_per_vol"/>
                       <localParameter id="Ca_Rest" value="0.1" units="subs_per_vol"/>
                   </listOfLocalParameters>
               </kineticLaw>
           </reaction>
           <reaction id="Ca_channel" reversible="true" fast="false">
               <listOfReactants>
                   <speciesReference species="Ca_EC" stoichiometry="1" constant="true"/>
               </listOfReactants>
               <listOfProducts>
                   <speciesReference species="Ca_C" stoichiometry="1" constant="true"/>
               </listOfProducts>
               <listOfModifiers>
                   <modifierSpeciesReference species="CaCh_PM"/>
               </listOfModifiers>
               <kineticLaw>
                   <notes>
                       <p xmlns="http://www.w3.org/1999/xhtml">
                           (J0 * Kc * (Ca_EC - Ca_C) / (Kc + Ca_C) * CaCh_PM)
                       </p>
                   </notes>
                   <math xmlns="http://www.w3.org/1998/Math/MathML">
                   <apply>
                       <times/>
                       <ci> PlasmaMembrane </ci>
                       <apply>
                           <divide/>
                           <apply>
                               <times/>
                               <ci> CaCh_PM </ci>
                               <ci> J0 </ci>
                               <ci> Kc </ci>
                               <apply>
                                   <minus/>
                                   <ci> Ca_EC </ci>
                                   <ci> Ca_C </ci>
                               </apply>
                           </apply>
                           <apply>
                               <plus/>
                               <ci> Kc </ci>
                               <ci> Ca_C </ci>
                           </apply>
                       </apply>
                   </apply>
                   </math>
                   <listOfLocalParameters>
                       <localParameter id="J0" value="0.014" units="litre_per_mole_per_second"/>
                       <localParameter id="Kc" value="0.5" units="subs_per_vol"/>
                   </listOfLocalParameters>
               </kineticLaw>
           </reaction>
       </listOfReactions>
   </model>
</sbml>
