The influence of trypsin and neuraminidase on content of serotonin in rat blood platelets.

Trypsin produced phasic changes (increase or decrease) in the serotonin levels in blood platelets depending on the initial concentration of serotonin in the platelets. The lowest concentration of trypsin that was used raised the content of serotonin in unloaded platelets, while all tested concentrations of trypsin lowered content of serotonin when the platelets were loaded with serotonin. Prolongation of time of incubation from 6 to 12 minutes revealed an action of some of the concentrations of trypsin that were previously inactive. Neuraminidase lowered serotonin levels in rat platelets. The effect of the highest concentration of neuraminidase was enhanced in presence of some of the concentrations of trypsin.