Whole blood platelet aggregation in humans and animals: A comparative study

Background. Many animal species are used to evaluate the performance and blood compatibility of cardiovascular devices, but interspecies differences in platelet activity have not been well characterized. This study measures platelet response to six agonists in human, dog, and calf blood. Materials and methods. We used whole blood impedance lumi-aggregometry to measure platelet aggregation and ATP release in blood samples from adult humans (n = 19), mongrel dogs (n = 19), and Holstein calves (n = 7). The agonists were collagen, ristocetin, arachidonic acid, thrombin, and three concentrations of both ADP and epinephrine. Results. Only collagen (1 mu g/ml) and ADP (5, 10, and 20 mu M) caused aggregation and ATP release in all samples. Canine platelets responded to all six agonists at all doses. Human platelets responded to everything except epinephrine at 2 and 100 mu M. Bovine platelets responded only to collagen, ADP, and thrombin. In bovine platelets, aggregation from collagen and ATP release from thrombin were significantly lower than the corresponding responses in human and canine blood. The aggregation induced by 10 mu M ADP was significantly higher in canine than in human platelets. Conclusion, Human, canine, and bovine platelets have very different responses to agonists. In these models, collagen (1 mu g/ml) and ADP (10 mu M) are the agonists of choice for investigating whole blood platelet aggregation because they provide the most consistent results between species. For ATP release, 1 U/ml thrombin is the recommended agonist and the dose for all three species, (C) 1999 Academic Press.