Research Area: Cardiovascular Disease Biological Activity: Hydralazine hydrochloride is a hydrochloride salt of hydralazine (Apresoline) that is a direct-acting smooth muscle relaxant with an IC50 of 1.9 mM. Hydralazine (Apresoline) is used to treat high blood pressure. Hydralazine hydrochloride works by relaxing the blood vessels so that blood can flow more easily through the body. Hydralazine hydrochloride increases guanosine monophosphate levels, decreasing the action of the second messenger IP3, limiting calcium release from the sarcoplasmic reticulum of smooth muscle. This results in vessel relaxation. Hydralazine hydrochloride dilates arterioles more than veins. Hydralazine hydrochloride recently has been identified as a nitric oxide donor. Activation of hypoxia-inducible factors has been suggested as a mechanism. Hydralazine hydrochloride relaxes vascular smooth muscles of arteries and arterioles, causing peripheral vasodilation and decreasing peripheral vascular resistance. These actions decrease blood pressure and increase heart rate, stroke volume, and cardiac output. [1][2][3][4] |