Reciprocal food sharing in the vampire bat

SummaryCuticle bleeding time (CBT) measurements in anesthetized rabbits were performed to assess the potential bleeding risks which may accompany the administration of tissue-type plasminogen activator (tPA) or vampire bat salivary plasminogen activator (BatPA). The dose of BatPA or tPA used in this study, 42 nmol/kg, was previously shown to be efficacious using a rabbit femoral artery thrombosis model (Gardell et al, Circulation 84:244, 1991). CBT was determined by severing the apex of the nail cuticle and monitoring the time to cessation of blood flow. CBT was minimally elevated (1.6-fold, p<NS) following bolus intravenous administration of BatPA; in contrast, bolus intravenous administration of tPA dramatically elevated CBT (6.2-fold, p<0.05). Rabbits treated with tPA, but not BatPA, displayed profound activation of systemic plasminogen and consequent degradation of Factor VIII and fibrinogen. Elevations in CBT after the administration of tPA were reversed by the replenishment of plasma Factor VIII activity to 40% of control, but were unaffected by complete replenishment of plasma fibrinogen. The results of this study suggest that the administration of BatPA, at a dose that promotes thrombolysis, may evoke a minimal bleeding risk, relative to an equi-efficacious dose of tPA. In addition, the tPA-provoked proteolytic consumption of Factor VIII may be a key contributor to the heightened bleeding risk.

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Vampire Bat Salivary Plasminogen Activator Promotes Robust Lysis of Plasma Clots in a Plasma Milieu Without Causing Fluid Phase Plasminogen Activation

Thrombosis and Haemostasis ◽

10.1055/s-0038-1656343 ◽

1992 ◽

Vol 68 (02) ◽

pp. 165-169 ◽

Cited By ~ 12

Author(s):

Timothy R Hare ◽

Stephen J Gardell

Keyword(s):

Plasminogen Activator ◽

Plasma Levels ◽

Fluid Phase ◽

Immunoblot Analysis ◽

Tissue Type ◽

Clot Lysis ◽

Plasma Clot ◽

Type Plasminogen Activator ◽

Iodine 125 ◽

Vampire Bat

SummaryVampire bat salivary plasminogen activator (BatPA), human tissue-type plasminogen activator (tPA) or streptokinase (SK) were incubated in human citrated plasma containing a plasma clot that was radiolabelled with iodine-125 fibrin(ogen). Complete clot dissolution by BatPA (30 nM) was associated with slight activation of “fluid phase” plasminogen; the plasma levels of functional fibrinogen and α2-antiplasmin decreased by only 8 and 19%, respectively. Addition of SK (3,600 IU/ml) to the clot-containing plasma caused complete clot lysis and massive activation of the “fluid phase” plasminogen, leading to >60 and 96% decreases of the functional levels of fibrinogen and α2-antiplasmin, respectively. Incubation of tPA (30 nM) in clot-containing plasma caused complete clot lysis as well as substantial activation of “fluid phase” plasminogen; the plasma levels of functional fibrinogen and α2-antiplasmin decreased by 45 and 79%, respectively. The profound degradation of fibrinogen in the SK and tPA but not BatPA-containing samples was confirmed by immunoblot analysis. Additional experiments showed that the presence of soluble clot lysate in plasma containing tPA enhanced the extent of fibrinogen degradation from 25% to >60%; the addition of soluble clot lysate to the plasma containing BatPA did not prompt further fibrinogen degradation. Finally, studies using exogenous α2-antiplasmin suggested that plasmin generated via tPA-mediated activation of “fluid phase” plasminogen does not play an important role in clot dissolution.

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