In the body NO signals smooth muscle to relax by activating guanylate cyclase, increasing cGMP, and decreasing calcium ion levels in the cell. No direct effect on cardiac or skeletal muscle. Increased venous pooling causing decreased preload. Dilation of veins predominates over that of arterioles. Decreased arterial resistance causing decreased afterload.
Vasodilation decreases myocardial workload and oxygen demand.
Coronary vessel dilation. This, combined with the reduction in preload, contributes to increased subendocardial perfusion. Improved metabolic efficiency. Reduced platelet aggregation. This may contribute to its effectiveness in treating unstable angina.