How do calcium-channel blockers work?
The heart is mainly made of special muscle cells which contract to pump blood into the arteries (blood vessels). The walls of the arteries also contain ‘smooth’ muscle cells. When these contract the artery narrows. The heart muscle cells and smooth muscle cells need calcium to contract. Calcium passes into these cells via tiny ‘channels’. Calcium-channel blockers reduce the amount of calcium that goes into these muscle cells. This causes these muscle cells to relax. So, the effects of these drugs are: • To widen the arteries which: • Reduces the blood pressure. • Helps to ease angina by widening the coronary arteries. • Can ease symptoms of Raynaud’s phenomenon. In this condition you have cold and painful fingers and toes caused by narrowing of the arteries in the hands and feet. • To reduce the force and rate of the heartbeat. This helps to prevent angina pains.
