Abstract: The maintenance of the concentration of intracellular Na⁺([Na⁺]_i) and the concentration gradient across plasma membrane plays critical roles in maintaining normal cell physiological function. The[Na⁺]_i of intact functioning biological samples can be measured by non invasive ²³Na NMR. The intra-and extracellular Na⁺ can be simultaneously quantified by using frequency chemical shift reagents (DyTTHA^3- and TmDOTP^5-), thereby permitting quantitative assessment of net Na⁺ movement. ²³Na NMR can be used to study Na⁺ changes in various physiological and pathological states and to diagnose disease. The information derived from ²³Na NMR help us to understand the mechanism of pathological changes such as ischemia and reperfusion injury, diabetes, osteoarthritis, liver dysfunction induced by burn trauma, and so on.

Key words: ²³Na NMR, Intracellular Na⁺ concentration, Biomedicine