Vasodilator

A vasodilator is a substance that causes blood vessels in the body to grow slightly wider by relaxing the smooth muscle in the vessel wall. This will reduce blood pressure (since there is more room for the blood) and might allow blood to flow around a clot. Several vasodilators are used as drugs.

Natural vasodilators and drugs that exploit them:

Nitric oxide
- Glycerol trinitrate
- Viagra
Adrenaline and noradrenaline vasodilate arterioles of the skeletal muscles. (By acting on beta-2 adrenergic receptors.) These chemicals cause vasocontriction elsewhere.
- Alpha-blockers and Beta-blockers (block the constricting effect of adrenaline.
Prostacyclin (PGI₂) as well as other prostaglandins.
Adenosine
- Adenocard - this is primarily used as an anti-arrhythmic.
Histamine
- Complement proteins C3a, C4a and C5a work by triggering histamine release from mast cells and basophils.
Atrial natriuretic peptide (ANP) - a weak vasodilator.
Bradykinin
Platelet activating factor (PAF)