The influence of low-power laser energy on red blood cell metabolism and deformability.

The aim of this study was to test the hypothesis that exposure of red blood cells (RBC) to low-power laser energy can modulate their metabolism and deformability. The effects of exposure to a He-Ne (lambda=632.8 nm), GaAlAs (lambda=780 nm) and GaAs (lambda=904 nm) lasers have been examined. Red cells diluted to a hematocrit of 45% were incubated in a humidified atmosphere of 95% air and 5% CO(2) at 37 degrees C, and exposed to three different laser beams held 5 cm from the target area to yield a spot surface area of 2 cm(2). Three red cell suspensions belonging to the experimental groups were treated with each laser beam by 5, 15 and 30 minutes, respectively. The temperature was constant during the exposure's time. Three control suspensions of RBC were kept for the same time as sham-irradiated groups. The erythrocyte elongation index (EEI) was evaluated using a Rheodyn SSD (Myrene, Roetgen, Germany). The enzyme activities of glucose-6-phosphate dehydrogenase (G-6-PD), glutathione peroxidase (GSH-Px) and glutathione reductase (GR) were assayed in each sample spectrophotometrically. Adenosine triphosphate (ATP) and diphosphoglicerate (2,3-DPG) levels were also assessed. No statistical differences were observed in the erythrocyte elongation index at shear stresses of 0.30, 0.60, 1.20, 3.00, 6.00, 12.00, 30.00 and 60.00 Pa after being irradiated for 5 and 15 minutes as compared to not irradiated ones. At 30.00 and 60.00 Pa a decrease (p<0.03 and p<0.05, respectively) in EEI has been observed after 30 min exposure to all three wavelengths of laser light when compared to the control. The antioxidant enzyme activities showed no significant changes following 5, 15 and 30 min of irradiation by all three laser wavelengths laser tested. Similarly, erythrocyte organic phosphate levels (ATP and 2,3-DPG) showed no significant changes following treatment by laser radiation. This study revealed that the low-power laser at 632.8, 780 and 904 nm wavelengths have little biological effects on red blood cells in vitro.