Halo lipids. VI. Stimulation of human and rabbit blood platelets by racemic halo analogues of O-alkyl-glycerophosphocholine.

Halo analogues of O-alkyl- glycerophosphocholines are shown to stimulate human and rabbit blood platelets. Using 50-500 microM, a concentration dependent platelet aggregation is triggered in human platelet-rich plasma. Distinctly lower concentrations up to 10 microM activate the platelets in rabbit platelet-rich plasma. Moreover, the halo analogues enhance aggregation and release reaction triggered by suboptimal concentrations of ADP. In protein poor mediums the halo lipids in a concentration of 50 microM or higher cause a complete lysis of platelets. These results indicate that the halo lipids tested show the typical behaviour reported on lysophosphatidic acids which has to be taken into account using these compounds for other purposes.