Haycraft’s seminal discovery of hirudin was followed a
century later by the discovery of other antihemostatic
agents in leech saliva: platelet-aggregation inhibitors,
coagulation inhibitors and destabilase. It is doubtful,
however, whether the known antihemostatic armamentarium
of H. medicinalis saliva can account for the prolonged
bleeding observed after a leech feed. Munro et
a196 examined the blood oozing from a leech bite.
During the first minute after the leech had dropped off,
whole blood clotting time, thrombin clotting time, and
prothrombin time were elevated, and ADP- and thrombin-
induced aggregation were inhibited. Coagulation
parameters and aggregation reverted to normal within
15 min. In our work, we found that hirudin and the