Aim To investigate the intracellular signalling relatedto the migration promoted by platelet-derived growthfactor (PDGF) .Methods Cultured smooth muscle cells(SMC) derivedfrom rats (A7r5) were used. Modified Byoden cham-ber technique was employed for migration accessment.Intracellular free calcium ion concentration was measured using Fure-2. Results PDGF-BB promoted migration of SMC andcaused an increase in of SMC, with peak re-sponse at concentration of PDGF 5 g/L. The migra-tion and increase in induced by PDGF weremarkedly inhibited by 1 00 mol/L BAPTA 1 97 ±30 vs 1 7.7± 6 nmol/L , P < 0.01 ) , a calciumchelator, and 50 mol/L genestein, a tyrosine kinaseinhibitor.Conclusion The increase in plasmic ionic calcium isone of early intracellular signalling after interaction ofPDGF and SMC. The migration of SMC induced byPDGF is either calcium dependent or tyrosine kinasedependent.