Vasodilators are a group of drugs, which relax the smooth muscle cells of the blood vessels and lead to an increased local tissue blood flow, a reduced arterial pressure and a reduced central venous pressure. Vasodilators reduce the cardiac pre-load as well as after-load and thereby reduce cardiac work. They are used in a variety of conditions including hypertension, cardiac failure and treatment/prevention of angina pectoris. Major groups are Ca²⁺-channel blockers (e.g. dihydropyridines), NO-donators (e.g. organic nitrates), K⁺-channel openers (minoxidil), phosphodiesterase inhibitors (e.g. sildenafil), Rho-kinase inhibitors (e.g. Y27632) or substances with unknown mechanism of action (e.g. hydralazine). Inhibitors of the renin-angiotensin-system (e.g. ACE inhibitors, angiotensin II receptor antagonists or renin inhibitors) also act as vasaldilators.

 Smooth Muscle Tone Regulation