<unk>  <unk>  chiefly prevents formation of the platelet plug involved in primary hemostasis (a part of blood clot formation). It does this by inhibiting platelet activation. It is also an effective vasodilator.<unk> 's interactions contrast with those of thromboxane (TXA2), another eicosanoid. Both molecules are derived from arachidonic acid, and work together with opposite platelet aggregatory effects. These strongly suggest a mechanism of cardiovascular homeostasis between these two hormones in relation to vascular damage.
Prostacyclin
Endothelin
Angiotensin II 
Prostaglandin
Vasopressin 
Vasopressin
Endrin
Endothelium-derived relaxing factor