Laser-induced stimulation of thromboxane B2 synthesis in human blood platelets: Role of superoxide radicals

Abstract Exposure of platelet-rich plasma to laser radiation at 3.5 W for 30 seconds reduced the threshold concentrations of adenosine diphosphate and l -epinephrine needed from complete platelet aggregation by 20% to 60% and by 30% to 50%, respectively. The irradiation of platelet-rich plasma with laser also increased the basal level of thromboxane A 2 from 8 platelets for each second of exposure. In contrast, the exposure of gel-filtered platelets to laser produced no effect on the prostanoid formation. However, the addiion of laser-exposed platelet-free plasma to gel-filtered platelets stimulated the synthesis of thromboxane A 2 in these cells. The effect of laser was completely blocked by adding superoxide dismutase or catalase to the platelet-rich plasma, indicating that the radiation-induced stimulation of thromboxane A 2 production was mediated through the generation of superoxide radicals. Electron microscopic studies indicated that the laser-induced stimulation of thromboxane A 2 production in platelet can occur without any noticeable damage in the cellular structure.