STUDIES ON THE INHIBITION OF ADRENALINE-INDUCED AGGREGATION OF BLOOD-PLATELETS

α-Adrenoceptors of platelets seem to differ from those of other cell types. The inhibitory effect of α-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 tested, only lisuride has a stronger inhibitory effect than those of natural ergot alkaloids.