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English - homeComparison of platelet aggregation during hibernation and non-hibernation in Scandinavian brown bears (Ursus arctos)
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LyssnaObjective
Brown bears are free from thrombotic events despite several months of inactivity during hibernation, but information on the coagulation system in bears is scarce.
Bears may serve as a comparative model for human thrombosis research, as inactivity is a known risk factor for venous thrombosis in humans.
Our objective was to study primary haemostasis by impedance aggregometry in bears inactive during
hibernation in winter, compared with their active state in summer.
Methods and materials
Whole blood was drawn from 6 wild brown bears (3 females, all bears between 2 and 3 years old) during hibernation in winter and during non-hibernation in summer.
We analyzed samples within 3 hours by multiple electrode platelet aggregometry using three different agonists: adenosine diphosphate (ADP, 6.4 µM), arachidonic acid (ASPI-test, 0.5 mM) or collagen (1µg/mL). Impedance, and thus aggregation, was quantified as arbitrary aggregation units (AU) after six minutes and area under the curve of arbitrary units (AUC).
Results
Platelet aggregation, expressed as AU and AUC, was markedly decreased during hibernationcompared to non-hibernation.
The differences were statistically significant for all the three different agonists using impedance aggregometry.
Platelet count was moderately but statistically significantly reduced during hibernation compared to non-hibernation (146 ± 47 vs 228 ± 39 x 109 L-1, P=0.02) but within this range the number of platelets most likely had little or no impact on platelet aggregation.
Conclusion
Platelet aggregation in brown bears is reduced during hibernation compared to their active state.
This finding may contribute to the ability of bears to endure 6 months of inactivity without thrombotic complications.
If the basis for the specific biochemical mechanisms involved in reduced platelet aggregation in bears can be determined, this might translate into useful applications for human medicine.
