Following vein grafting, endothelial damage initiates vascular smooth muscle cell (VSMC) migration to the intima leading to neointimal hyperplasia. Inhibition of VSMC migration is therefore a therapeutic target in vascular disease. Cyclic adenosine monophosphate (cAMP) inhibits VSMC migration and activation of this pathway could be used to prevent neointimal hyperplasia. Prostacyclin analogues, such as beraprost and iloprost, bind to prostanoid receptors and induce cAMP production. This project aims to characterise the effects of prostacyclin analogues in VSMC migration and determine the cAMP downstream molecules involved, specifically examining the role of protein kinase A (PKA) and exchange protein activated by cAMP (Epac). Saphenous veins were obtained from patients undergoing coronary artery bypass. VSMCs were primary cultured and migration measured using a chemotaxis chamber. Cells were seeded onto membranes with 8 µm pores and platelet-derived growth factor-BB (PDGF) (10 ng/ml) was added to the lower well of the chemotaxis chamber. Chemotactic cell migration after 4 hours at 37°C was significantly increased with PDGF in comparison to the migration towards the vehicle (PDGF – 402 ± 31 migrated cells, vehicle – 148 ± 14, n=14 each group, mean ± S.E.M, p<0.05, ANOVA). Cell migration stimulated by PDGF was significantly inhibited in the presence of iloprost (100 nM) (174 ± 13 migrated cells, n=4) or beraprost (100 nM) (130 ±11, n=4) in comparison to PDGF alone (324 ± 26, n=4, p<0.05). To examine potential mechanisms of beraprost/iloprost inhibition of PDGF-induced migration, selective agonists for direct activation of PKA (N6-Phenyl-cAMP, 5µM) and Epac (8-CPT-2′-O-Me-cAMP, 2µM) were added to the bottom well of the chemotaxis chamber. Both the Epac agonist and PKA agonist significantly reversed migration towards PDGF in comparison to PDGF alone (PDGF – 438 ± 53 cells migrated; PDGF + Epac agonist – 275 ± 22; PDGF + PKA agonist – 313 ± 35, n=8 each group, p<0.05). As Epac and PKA agonists inhibit migration and could both be activated by prostacyclin analogues, the effects of a PKA inhibitor KT-5720 (2 µM) was examined. KT-5720 did not significantly change the inhibition of PDGF-induced migration previously observed with beraprost (PDGF + beraprost – 123 ± 23 cells migrated; PDGF + beraprost + KT-5720 – 160 ± 42, n=3 each group, not significant). This potentially indicates that prostacyclin analogues may inhibit VSMC migration via activation of Epac. To examine Epac localisation in VSMCs, labelling of cells with the Epac1 antibody was investigated. Epac1 was localised to the perinuclear region of cells and at the leading edge of migrating cells. In conclusion prostacyclin analogues inhibit VSMC migration, and activation of Epac may be sufficient for this inhibitory pathway. This may provide a new therapeutic target to prevent neointimal hyperplasia.