Measurement of intracellular ionized magnesium.

Recent advances in methods for measuring Mgi have advanced our understanding of Mgi homeostasis. Several methods exist for measuring Mgi; all have strengths and weaknesses and one needs to match the experimental needs with the limitations of the method. For example, if one needs rapid (ms) time resolution, or only relative directional changes in a cell that is not easily impaled with an electrode, the fluorescent indicators may best suit ones needs. If on the other hand one wants to measure Mgi in a perfused organ, then the NMR methods may best address one's needs. If one needs to accurately know Mgi in a papillary muscle or some other tissue which is readily impaled then ion-selective microelectrodes may be the method of choice.