Effects of the helium-neon laser on rat kidney epithelial cells in culture

The cellular mechanisms of action of low power lasers are only partially understood. Therefore, we have studied effects of helium-neon (He-Ne) laser irradiation in a cell culture model. The studies were performed with the permanent rat kidney cell line RK-L. By electron microscopy, significant ultrastructural changes of the cells were seen after He-Ne irradiation at 40 mW/cm² for 4h (569 J/cm²), including detritus-like formations of the cell organelles close to the nucleus. While such changes were not observed after 1 h irradiation (142 J/cm²), the number of cells in mitosis increased under this condition. In addition, the rate of incorporation of³H-thymidine into DNA decreased transiently 6-9 h after 1 h He-Ne irradiation of the cells. The consumption of glucose was also lowered for 10 h after irradiation, while the production of lactate increased. Finally, the synthesis of prostaglandin E₂ was reduced following irradiation. These results show that the He-Ne laser induces significant effects at the cellular level. In addition, our findings support the concept that the biological effects of low power laser treatment involve changes in the cell cycle.