[Pharmacological investigations on the adrenalin-thrombin-induced platelet aggregation in dogs]

Adrenaline alone did not induce aggregation of canine blood platelets in citrated plasma in vitro; however, it potentiated the aggregation caused by thrombin concentrations which are too low to induce coagulation. Simultaneous infusion of adrenaline and thrombin resulted in accumulation of 111In-labelled platelets in the lung and in the heart as measured by means of a gamma camera. Separately infused adrenaline or thrombin did not change the distribution of radioactivity. In vitro and in vivo hirudin and cyproheptadine inhibited the adrenaline-thrombin-induced platelet aggregation. Dihydroergotamine exerted no in vivo effect at the doses used.