Low-intensity light induces vasomotion

To investigate the mechanism of light induced vasomotion, we studied vascular tension change in normal buffer solution. The results showed that the light induced vasocontraction may have been due to thermal effect of the light, however, the vasorelaxation was not caused by the thermogenesis. We conclude that primary photochemical product, which is probably nitric oxide originated from photodissociation of nitro groups, may produce the vasorelaxation. This preliminary investigation suggests that ultraviolet irradiation may be available to treatment for vasospasm.