The release of platelet activating factor (PAF) induced 14C-arachidonic acid (14C-AA) in the bovine cerebral microvascular endothdial cells (CMEC) and arterior cerebral artery smooth muscle cells (ACASMC) and the antagonism of SZ-1 are described. The results showed that 14C-AA incorporated into the cells rapidly and PAF 0.1-20?mol/L dose-dependently stimulated the AA release significantly. It indicated that the action of PAF on the cerebrovascular system was associated with the stimulation of AA release. SZ-1 0.2-20?nol/L dose-dependently inhibited the PAF induced AA release in CMBC and ACASMC, and PAF induced aggregation of washed rabbit platelets, but did not inhibited ADP or AA induced aggregation of platelet-rich plasma(PRP), and PAF production in CMEC, indicating the specific antagonism of SZ-1 on PAF receptor.