Optimization of Multiplate(®) whole blood platelet aggregometry in the Beagle dog and Wistar rat for ex vivo drug toxicity testing

Abstract

This study was performed to optimize and standardize the use of the Multiplate(®) whole blood impedance aggregometer in the Beagle dog and Wistar rat for use in a research laboratory environment. The anticoagulants citrate, heparin and hirudin were compared and platelet aggregation responses to ADP, collagen, arachidonic acid and Par-4 agonist were evaluated to determine their half maximal effective concentrations (EC(50)) in blood containing low concentrations of a drug solvent (0.1% DMSO). The results indicate that citrate anticoagulation is not suitable for Multiplate(®) whole blood aggregometry because of the presence of spontaneous aggregation. ADP and collagen were found to be appropriate agonists for both species, whereas in the Beagle dog Par-4 agonist failed to induce aggregation and arachidonic acid induced platelet aggregation showed a high interindividual variability. The agonists EC(50) calculated in hirudin blood were 2.70 μM ADP, 0.85 μg/ml collagen, 0.03 mM arachidonic acid and 165.7 μM Par-4 agonist in the Wistar rat, and 0.95 μM ADP and 0.23 μg/ml collagen in the Beagle dog.