1- Haemostatic Mechanism3

Growth factor
PDGF found in the α granules of platelets stimulates vascular
smooth muscle cells to multiply and this may hasten vascular
healing following injury.
Natural inhibitors of platelet function
1- Nitric oxide (NO) is constitutively released from endothelial cells
and also from macrophages and platelets. It inhibits platelet
activation and promotes vasodilatation.
2- Prostacyclin synthesized by endothelial cells also inhibits platelet
function and causes vasodilatation by raising cyclic guanosine
monophosphate (GMP) levels.
3- An ectonucleotidase (CD39) helps prevent platelet aggregation in
the intact vessel wall.