The effects of heparin and annexin V on fibrin accretion after injury in the jugular veins of rabbits

• Published in: Thrombosis and haemostasis Vol. 69; no. 3; p. 227
• Main Authors: Van Ryn-McKenna, J, Merk, H, Müller, T H, Buchanan, M R, Eisert, W G
• Format: Journal Article
• Language: English
• Published: Germany 1993
• Subjects: Animals; Annexin A5 - pharmacology; Annexin A5 - therapeutic use; Blood Coagulation; Fibrin - metabolism; Fibrinogen - metabolism; Heparin - pharmacology; Heparin - therapeutic use; Jugular Veins - injuries; Jugular Veins - metabolism; Rabbits; Thrombin - metabolism; Thrombosis - prevention & control
• ISSN: 0340-6245
• DOI: 10.1055/s-0038-1651585

We compared the relative abilities of unfractionated heparin and annexin V to prevent fibrin accretion onto injured jugular veins in vivo. Heparin was used to accelerate the inhibition of thrombin by antithrombin III, and annexin V was used to inhibit the assembly of the prothrombinase complex on phospholipid surfaces, thereby blocking thrombin generation. Rabbit jugular veins were isolated in situ, a 2 cm segment was injured by perfusing it with air, and then blood flow was re-established. Five minutes later, each rabbit was injected with heparin (20 U/kg) or annexin V (0.3 mg/kg) and then with 125I-fibrinogen. The amount of 125I-fibrin accumulation onto each injured vessel wall segment was measured 4 h later. Each injured vessel was completely de-endothelialized as a result of the air perfusion as demonstrated by electron microscopy. 125I-fibrin accretion onto the injured jugular veins was enhanced 2.4-fold as compared to the uninjured veins in sham-operated animals. Heparin treatment did not reduce fibrin accretion, whereas, annexin V treatment decreased fibrin accretion by 60%, p < 0.05. This latter effect was achieved without sustained circulating anticoagulation. Additional experiments confirmed that the inhibitory effect of annexin V on fibrin accretion was associated with a surface specific effect, since more annexin V bound to the injured jugular vein segments as compared to the non-injured jugular veins.