Ultraviolet light: a new stimulus for the induction of platelet aggregation

Exposure to ultraviolet light (253.7 nanometers) causes mammalian blood platelets to aggregate. Aggregation is markedly enhanced in the presence of extracellular fibrinogen and is followed by the grodual of relatively small amounts of nucleotide and serotonin. Aggregation is inhibited by ethylenediamine tetraacetic acid or a combination of 2-deoxy-D-glucose and antimycin A. Adenosine, apyrase, and prostaglandin E(1) produced slight inhibition. The effect of exposure to ultraviolet light is cumulative and lasting. This agent may be used to study the process of platelet aggregation after the removal of the stimulus, by delaying the addition of fibrinogen until after cessation of irradiation. Thus ultraviolet light is the first agent known which may be used to study platelet aggregation in a period following its removal.