First know how to make a question: what do you mean, you want to measure the calcium intracellular activity? or the oscllations of the same? do you know the difference between activity and concentraiton in free solution of a given ion?
Most institutions have a calcium imaging set up and if you have access to one, it would be pretty cheap to produce alot of data with calcium imaging by loading your cells will calcium sensitive fluorescence ionophors that are reasonably cheap. Molecular Probes have a long list of them.
I apologize for the incomplete information. In an attempt to maintain discretion, i ended u providing inadequate information. My intention is to measure the intracellular calcium concentration in the cells. Anyway, there is nothing more I can reveal at this point, so I will probably have to stop right here. Thanks anyway.
even though loading the cell with a calcium indicator is a very wide spread method, whenever possible I prefer the use of genetically encode calcium indicators such as the GCaMP family. This system allows you to do several types of experiments in vivo that are not possible by passive loading of cells. Depending on the system that you use this could be or not a feasible option.
Hi Gabriela, To measure absolute concentration, you will have to use ratiometric measurement. This can be with genetically encoded probes (see Miyawaki's lab work) or the AM versions of Fura2 (using UV) or Asante Calcium red (newer, visible light). I hope this helps, good luck, Thomas