[Effect of NAD+ against radiation injury and its dose-effect relationship].

Objective: To explore the effect of NAD+ against radiation injury and its dose-effect relationship.
Methods: L02 liver cells cultured in RPMI 1640 medium containing 10% fetal calf serum were exposed to X-ray irradiation followed by immediate application of NAD+. The cellular viability was analyzed by MTT assay and the apoptotic cells were detected by TUNEL methods to observe the damages of L02 liver cells induced by X-ray exposure and analyze the dose-effect relationship of NAD+.
Results: The viability of L02 liver cells was decreased with increasing dose of X-ray irradiation. The most obvious growth inhibition of L02 cells occurred 24 h after the irradiation. NAD+ significantly increased the cell survival rate after irradiation, and this effect was gradually increased within the concentration range of 100-1000 microg/ml; at higher concentrations, the survival rate of the irradiated L02 cells showed no significant increase.
Conclusion: NAD+ provides partial protection of the liver cells against radiation injury, and the effect is positively correlated to NAD+ concentration within a certain range.