Calcium channel blockers are antianginal and antihypertensive. They inhibit the movement of calcium ions across the membranes of cardiac and arterial muscle cells. This inhibition of transmembrane calcium flow results in the depression of impulse formation in specialized cardiac pacemaker cells, slowing of the velocity of conduction of the cardiac impulse, depression of myocardial contractility, and dilation of coronary arteries and arterioles and peripheral arterioles. These effects lead to decreased cardiac work, decreased cardiac energy consumption, and increased delivery of oxygen to myocardial cells.