Stimulation of vascular prostacyclin synthesis by extracellular ADP and ATP.

Extracellular ADP and ATP stimulated the synthesis of prostacyclin - as reflected by the release of 6-keto-PGF1 alpha - in the rabbit aorta, the rabbit pulmonary artery and the rat aorta. A doubling of 6-keto-PGF1 alpha output was produced by 3 microM ADP. Adenosine had no effect and the stimulation by ADP was blocked by quinidine, but not by theophylline. This stimulation was abolished by indomethacin and lost after mechanical removal of the endothelium. Stimulation of vascular prostacyclin synthesis by ADP released from aggregating platelets could help localize thrombus formation to areas of vascular damage.