ISSN:
1433-2981
Keywords:
Key words:Bleeding – Coagulation – Hirudin –Hirudo medicinalis–Hirudo nipponia– Leeches
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract: Selected antihaemostatic parameters associated with the bite of the Asian medicinal leech Hirudo nipponia were investigated in human volunteers. This study confirms earlier work on Hirudo medicinalis, in that the wound from a leech bite bleeds for hours even though blood coagulates normally after about 15 min. The whole blood clotting time for H. nipponia after 1 min was 12.88 ± 3.15 min, comparable to that for H. medicinalis, but in both cases clotting time returned to control levels after about 15 min. However, the duration of bleeding from the bite of H. nipponia (mean = 210 min) was consistently shorter than H. medicinalis, even when adjusted for size differences (mean = 490 min). Similarly, the blood flow rate from H. nipponia (mean - 39 μl/min) is markedly slower than H. medicinalis (mean = 200 μl/min). The total blood lost from the host, therefore, was approximately ten times more with H. medicinalis than H. nipponia. Collagen-induced platelet aggregation was significantly impaired in blood from the H. nipponia bite wound in 25 min. This may indicate that the prolongation of bleeding is caused by inhibition of platelet aggregation rather than by thrombin inhibition alone. In both species, the saliva of the leech contains a potent antithrombin whose inhibitory activity returns to normal levels approximately 15 min after cessation of feeding. The internal amino acid sequence of the thrombin inhibitor secreted by H. nipponia into the saliva is unexpectedly different (55%) from that of hirudin secreted by H. medicinalis. This difference in sequence is reflected in the lack of neutralisation by the polyclonal antibody to hurudin from H. medicinalis. Blockage of the N-terminal in antithrombin from H. nipponia appears to be a further real difference compared to hirudin from H. medicinalis. The biological significance, if any, of these differences between species in bleeding time and antithrombin structure remains an open, but intriguing, question.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s005800050021
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