Abstract: In this paper ²³Na NMR technique with shift reagent Dy(PPPi)₂^7- was used to study a new type of photosensitizer-Hypocrellin B which photosensitized damage on Na⁺ permeability of ascitic hepatoma cells. The experimental results show that intracellular Na⁺ concentration increases with both light dose and photosensitizer concentration. It was also observed that the chemical shift of ²³Na_out NMR peak moved to downfieid as illumination time was increased in the presence of HB.
Analysis indicates that the changes of chemical shift relate to the loss of intraceilular K⁺ and K⁺ competes with Na⁺ for shift reagent. Therefore, the changes of chemical shift may be an index of photosensitized damage. The relation between the increase of Na⁺ concentration and cell death was discussed.

Key words: Hypocrellin B, Ascitic hepatoma cells, ²³Na NMR, Na⁺ permeability