Trypsin mediates a release of arachidonic acid with resultant increase in O2 consumption (a reflection of cyclo-oxygenase activity) by whole human platelets that is similar to thrombin's effect on these cells. The trypsin and thrombin effects can be differentiated in two ways: (1) at saturating concentrations the measured effects of trypsin greatly exceed those of thrombin; (2) EGTA ethanedioxybis(ethylamine)-NNN'N'-tera-acetate augments the effect of thrombin but not of trypsin. Thus trypsin and thrombin probably act at different loci in the pathway that induces phospholipase activity in human platelets.
Pickett et al. (Mon,) studied this question.