# closed_cell.ode # This XPPAUT file contains the program for calcium oscillations in a cell # in which total calcium is conserved (closed cell model). It was used to # make Fig. 14A in: S. S. Stoijilkovic, J. Tabak, R. Bertram, # "Ion Channels and Signaling in the Pituitary Gland", # Endocrine Reviews, 31:845-915, 2010. # Variables: # C -- cytosolic calcium concentration # h -- inactivation variable for the IP3 receptor # # ER fluxes Jer_out = (L + P*( (IP3*C*h)/((IP3+Ki)*(C+Ka)))^3 )*(Cer - C) Jer_in = (Ve*C^2)/(Ke^2+C^2) # The equations (Cer is calcium concentration in the ER) dC/dt = fi/Vi*(Jer_out-Jer_in) dh/dt = A*(Kd-(C + Kd)*h) Cer = (Ct - C)/sigma # # The parameters # IP3 pulse # set pulse=0 for no pulse, pulse=1 for a pulse of IP3 par pulse=1, IP3pulse=0.8 par tpulse=50, tduration=100 # IP3 = uM par IP3bas=0 # Ct = uM par Ct=2 par fi=0.01 # Vi = pL par Vi=4 # L,P = pL/s par L=0.37 par P=26640 # C, Cer, I, Ki, Ka, Ke, Kd = uM par Ki=1.0 par Ka=0.4 # Ve = aMol/s [sic] par Ve=400 par Ke=0.2 par A=0.5 par Kd=0.4 par sigma=0.185 # Apply the pulse protocol ts = t-tpulse ts2 = t-(tpulse+tduration) Ip3 = IP3bas+pulse*(heav(ts)-heav(ts2))*IP3pulse # # The initial conditions C(0)=0.02 h(0)=0.95 # aux Cer=Cer # @ meth=qualrk, total=200, dt=0.1, maxstor=10000 @ xp=t, yp=c, xlo=0,xhi=200,ylo=0,yhi=1.5 @ bounds=100000000, toler=1.0e-9, atoler=1.0e-9 @ bell=off done