Using a loaded table in the main program in a function

I have the user of my matlab program load a table and my code reads the values for certain properties (stored in columns) from the table. I wrote a Matlab function that would interpolate the values from the table.

function [rho_o,B_o,mu_o,Rso] = oil_prop_sat(Po)

rho_o=interp1(Po_data(1:10),rho_o_data(1:10),Po,'linear');

B_o=interp1(Po_data(1:10),B_o_data(1:10),Po,'linear');

mu_o=interp1(Po_data(1:10),mu_o_data(1:10),Po,'linear');

Rso=interp1(Po_data(1:10),Rso_data(1:10),Po,'linear');

But when I try and use the function into the main program, it gives my the error Undefined function or variable 'Po_data'. I understand that because I am not loading the data into the function, hence it is unable to find anything named Po_data. But I don't want the user to reinput the table every time I have to run the function (which is a lot of times).