In the previous article , we discussed Digitalis, the magical glycoside useful in heart failure. In this article, we'll take a look at the potent heart failure drug, Digitalis. Nitrates are a group of drugs that act on blood vessels and dilate them. By relaxing smooth muscle in the vessel wall, they produce an increase in diameter which in turn increases the volume of blood flowing through them.
Nitrates dilate both arteries and veins.
The effect on veins is slightly more prominent. Venous return to the heart decreases, with a consequent reduction in the tension in the ventricular wall. This leads to a lowering of oxygen requirement of heart muscle, a desirable effect in patients with ischemic heart disease caused by coronary atherosclerosis. Nitrates have another more direct effect on the coronary arteries - they act on the wall of the coronary artery and dilate it, causing an increased flow of blood to the heart muscle. NO causes smooth muscle to relax, and also acts on blood platelets making them less adhesive.