Studies on the inhibition of adrenaline-induced aggregation of blood platelets.

alpha-Adrenoceptors of platelets seem to differ from those of other cell types. The inhibitory effect of alpha-adrenoceptor-blocking agents on adrenaline-induced aggregation of human platelets does not parallel that on adrenaline-induced contraction of rabbit aortic strips. The most potent inhibitors of adrenaline-induced platelet aggregation are the dihydrogenated ergot alkaloids of the peptide type. Among the other ergoline derivatives testes, only lisuride has a stronger inhibitory effect than those of natural ergot alkaloids.