Effects of infrared and low-power laser irradiation on cell viability, glutathione and glutathione-related enzyme activities in primary rat hepatocytes.

BACKGROUND AND PURPOSE Both infrared and low-power laser have been applied to improve circulation, wound repair, and pain control. Infrared and low-power laser therapies have the potential for stimulating enzyme activities which might contribute to increased glutathione (GSH) concentration and provide protection against oxidative damage. This study investigated cell viability, and GSH and its related enzyme activities in rat hepatocytes after irradiation. METHODS Hepatocytes were isolated from 8-week-old male Sprague-Dawley rats and the cultures were divided into infrared, laser, and control groups. The cells were treated with infrared and low-power laser at a distance of 35 cm for 20 minutes. The cell morphology, lactate dehydrogenase (LDH) leakage, lipid peroxidation, GSH concentration, GSH peroxidase, GSH reductase (GRd), and GSH S-transferase activities were measured after irradiation. RESULTS The morphology and LDH leakage of hepatocytes in the irradiation groups did not differ significantly from those of the control group. After infrared irradiation, a significant decrease in thiobarbituric acid-reactive substances and an increase in GSH concentration were found after 48 hours of incubation compared to the control group (p < 0.05). Furthermore, laser irradiation resulted in a significant increase in GRd activity after 48 hours of incubation compared to the control group (p < 0.05). A 48-hour incubation period produced greater GRd activity in all groups compared to a 24-hour period (p < 0.05). CONCLUSIONS Irradiation did not damage rat hepatocytes in this study. Infrared was shown to stimulate GSH production, while laser irradiation increased GRd activity.