Pavikirthi - in the callback for your first pushbutton, update the handles structure with the value of the variable that you wish to save. i.e.
handles.myVar = someValue;
guidata(hObject, handles);
(The above assumes that both hObject and handles are inputs to your callback.)
Now, in the other pushbutton callback, you can reference myVar directly using the input handles object as
if isfield(handles,'myVar')
% do something with this variable
end
The above check makes sure that myVar is a field in handles before you try to access it.
