How is mechanism of action of hydralazin?

Hydralazine inhibit inositol trisphosphate-induced Ca2+ release from the sarcoplasmic reticulum in arterial smooth muscle cells It acts by producing relaxation of vascular smooth muscle, primarily in arteries andarterioles. This results in decreased peripheral resistance and, therefore, blood pressure. The directacting smooth muscle relaxants, is not used as primary drugs to treat hypertension. Used to treat moderately severe hypertension