%**********************************************************************************
%
%                CalC version 5.4.0, script "FCT_Fig7.par"
%                       Victor Matveev, January 4, 2005
%
%                    "Facilitation through Buffer Saturation: 
%                 Constraints on Endogenous Buffering Properties"
%                      V. Matveev, A. Sherman and R. Zucker
%                      Biophys. J. (2004) 86:2691-2709
%
%  Execute "calc FCT_Fig7.par control" (or "calc FCT_Fig7.par control | xmgr -pipe") 
%  to reproduce Figs. 6B and 7 (control curve - no Fura-2) of the Manuscript.
%
%  Execute "calc FCT_Fig7.par fura" (or "calc FCT_Fig7.par fura | xmgr -pipe") 
%  to reproduce the Fura-2 curve in Fig. 7.
% 
%**********************************************************************************

path = ""                   % If running under Windows, specify here the path to the
                            % directory containing the script imported below
file = path "FCT_main.par"
include file                % Import the simulation parameters from the main script,
                            % which defines everything but the buffer's parameters:

Buffer.D = 0.2              % Diffusion coefficient is 0.2 um^2/ms
Buffer.total = 700          % Concentration = 700 uM
Buffer.KD = 1.4             % Affinity = 1.4 uM
Buffer.kplus = 0.5          % Binding rate = 0.5 / (uM ms)

control = 0; fura = 1;      % dummy constants corresponding to the two possible
                            % command-line options

if ($2 == fura) then        % If the command-line argument is "fura", then
   buffer Fura              % define the second buffer, Fura-2
   Fura.D = 0.118           % Diffusion coefficient is 0.118 um^2/ms
   Fura.total = 200         % Concentration = 200 uM
   Fura.KD = 0.360          % Affinity = 360 nM
   Fura.kplus = 0.27        % Binding rate = 0.27 / (uM ms)
endif

plot  Ca1                   % Plot [Ca2+] concentration at the three locations 
plot  Ca2                   % (see Fig. 6B)
plot  Ca3

% Now, since release is quantified as the fourth power of [Ca2+], to calculate
% facilitation we need to measure the peaks in Ca2+ concentration achieved for
% each of the five pulses:

P1 max Ca2 0  3    % peak [Ca2+] at site #2 achieved at the first AP 
P2 max Ca2 10 13   % .. and so on for the other 4 pulses in the train. The reason
P3 max Ca2 20 23   % the maximum is tracked over a period of three ms is that, if 
P4 max Ca2 30 33   % the buffer is fixed, the [Ca2+] peak may significantly lag 
P5 max Ca2 40 43   % behind the end of the square ICa pulse.

% At the end of the simulation, the following print statements will print out the
% STF for each of the last four pulses in the five-pulse train (see Eq. 9)

print  "Facilitation at the 2nd pulse = " (P2/P1)^4 - 1 
append "Facilitation at the 3rd pulse = " (P3/P1)^4 - 1 
append "Facilitation at the 4th pulse = " (P4/P1)^4 - 1 
append "Facilitation at the 5th pulse = " (P5/P1)^4 - 1 

print.file = stderr  % Designate the terminal for the output 

% Uncomment one of the following, depending on your plotting preferences, to see
% the Ca2+ concentration traces:

% plot.print "FCT."   % Specifies the prefix for all output data files   
% plot.method xmgr       
% plot.method gl

% The end