Abstract: AimTo study the inhibitory effect of ginkgolide B (BN52021) on the PAF induced changes of chemotaxis of murine peritoneal macrophages and the related polymerization of F-actin. MethodsChemotaxis assays were performed using a modified 48-well Boyden chamber. Actin polymerization of murine peritoneal macrophages was analyzed by flow cytometry using a specific fluorescent stain. ResultsPeritoneal macrophages significantly migrated toward platelet-activating factor (PAF) through a micropore filter; however, in the presence of PAF receptor antagonist BN52021 (0.01 nmol·L^-1-0.1 μmol·L^-1), the migration was significantly inhibited. Moreover, BN52021 inhibited the actin polymerization of murine peritoneal macrophages induced by PAF in the presence of Ca²⁺, but not in Ca²⁺-free medium. ConclusionThe results suggested that preventing polymerization of F-actin may be a pathway by BN52021 to inhibit the chemotaxis of macrophages, and this effect seems to be Ca²⁺ dependent. The data further indicated that inhibition of PAF induced macrophage chemotaxis is an important mechanism underlying the anti-inflammatory action of BN52021.