Summary
Plasma defibrinogenated dogs were used to study the influence of conventional heparin
and a low molecular weight heparin fragment (Fragmin®, mean MW 5,000 d) on platelet
dependent hemostasis. The heparins were given intravenously in gravimetri- cafly equal
doses. The bleeding from standardized skin flap wounds and platelet aggregation (ADP
and thrombin) was studied. In comparison, higher doses of the fragment than of heparin
were required to increase the bleeding. ADP-induced aggregation in defibrinogenated
platelet rich plasma (after addition of normal dog plasma) was potentiated by both
heparins. After injection of heparin or the fragment, ADP induced platelet aggregation
without prior addition of normal plasma to the testtube.
In conclusion the heparin fragment affected bleeding to a less extent than conventional
heparin. One explanation might be a weaker inhibition of thrombin-induced platelet
aggregation.
Keywords
Heparin-fragment - Bleeding time - Platelet aggregation - Dog
