# JNE_fig2.ode # This code was used to generate Fig.2 in the article # "Investigating Heterogeneity of Intracellular Calcium Dynamics in Anterior # Pituitary Lactotrophs Using a Combined Modelling / Experimental # Approach" by M. Tomaiuolo, R. Bertram, A. Gonzalez-Iglesias, # and J. Tabak, Journal of Neuroendocrinology 22:1279-1289, 2010 # To reproduce Fig. 2 # run the file in XPP and the calcium trace will be plotted # when the simulation is complete # click on the "Graphic stuff" and then # click on "add curve" # select Ceq as the variable to be plotted on the Y axis # click OK # This file contains the calcium subsystem only. It has been modified # to simulate application of IP3. # Variables: # # c -- cytosolic calcium # cer -- ER calcium c(0)=0.0877 cer(0)=132 # conductance in pS # currents in fA # Ca concentrations in uM # time in ms # Parameters # Run control parameters: par ip3pulse=10, Dpip3=0.0004 par kclpulse=0, vdep=40 # Pulse protocol parameters: par tpulse=5000, tduration=40000 #Ica par gca=1000, vhold=-60 num vm=-20, sm=12 par vca=25 # Ca fluxes (in uM ms^(_1)) par pleak=0.0002, kpmca=0.15, pip3init=0 num fcyt=0.01, fer=0.01 # vcyt_er = v_cyt/v_er; only ratio is needed par vcyt_er=30 par kserca=0.3 # Miscellaneous number alpha=4.5e-06 # Functions minf = 1/(1+exp((vm-v)/sm)) ica = gca*minf*(v-vca) Jin =-alpha*ica Jpmca = kpmca*c Jserca = kserca*c Jrelease = (pleak+pip3)*(cer-c) # Apply the pulse protocol ts = t-tpulse ts2 = t-(tpulse+tduration) pip3 = pip3init+ip3pulse*(heav(ts)-heav(ts2))*Dpip3 v = vhold+kclpulse*(heav(ts)-heav(ts2))*vdep # Equilibrium c Ceq = (Jin+(pleak+pip3)*cer)/(kpmca+kserca+pleak+pip3) omega = (kserca+pleak+pip3)/(kserca+kpmca+pleak+pip3) # Solution to ER quation par cer_init=132 lambda2=-fer*Vcyt_er*(1-omega)*(pleak+pip3) lambda3=fer*Vcyt_er*omega*Jin lambda1=lambda3/lambda2 + Cer_init Cer_sol=lambda1*exp(lambda2*ts)-lambda3/lambda2 # Equations c' = fcyt*(Jin-Jpmca-Jserca+Jrelease) cer' = fer*vcyt_er*(Jserca-Jrelease) aux tsec=t/1000 aux Ceq=Ceq aux Cer_sol=Cer_sol aux res_cer=cer/100 aux pip3=pip3 aux v=v aux peak=(Jin+(pleak+pip3)*cer_init)/(kpmca+kserca+pleak+pip3) aux decay=-lambda2 aux omega=omega aux slope=-lambda2/((Jin+(pleak+pip3)*cer_init)/(kpmca+kserca+pleak+pip3)) @ meth=rk4, toler=1.0e-10, atoler=1.0e-10, dt=10.0, total=100000, maxstor=200000 @ bounds=10000000, xp=tsec, yp=c, bell=off @ xlo=0, xhi=40, ylo=0.0, yhi=1.5 done