Beta-Blockers and Calcium-Channel Blockers: What Precisely Do They Block?

In 1988, I remember my father was taking atenolol which was prescribed by his doctor as a treatment for his hypertension. But after another round of examinations done to ascertain his heart condition, his doctor changed the prescription to nifedipine.

Note that the first medicine prescribed to my father, atenolol, belongs to a group of heart drugs known as beta-blockers, while the second - nifedipine - is one of the well-known newer heart medicines called calcium-channel blockers. But why are these drugs termed "blockers"? What precisely do they block, and how exactly do they work in treating hypertension?

Introduced in the late 1960s, beta-blockers also include other similar complicated-sounding names, such as timolol, metoprolol, pindolol, and propranolol, the latter being the best known. These beta-blockers work on the blood vessels and the heart muscle, both of which contain groups of cells that receive stimuli, known as beta-receptors. Once these receptors get stimulated, they cause the heart to beat harder and faster; blood pressure is raised as a result of this. The role of the beta-blockers is to block these receptors so that the heart's beating becomes less strong and slower, thereby lowering blood pressure.

The effects of beta-blockers are, to a great extent, valuable for a number of heart conditions. For instance, beta-blockers relieve angina (a distinguishing feature of coronary artery disease, characterized by a feeling of pressure or tightness in the chest) by reducing the cardiac muscle's requirement for oxygen. Any of the beta-blockers can be used to fight high blood pressure. They are likewise effective in treating the different kinds of abnormal heart rhythms, or arrhythmias.

The calcium-channel blockers, on the other hand, were introduced in 1981. This group of heart drugs includes, apart from nifedipine, two other names that are equally difficult to say or pronounce: diltiazem and verapamil. To appreciate the role played by calcium-channel blockers in the treatment of certain heart conditions, especially arrhythmias and angina, we have to understand that calcium molecules are key players in the possible constriction of blood vessels. Plainly as their name suggests, calcium-channel blockers block the passages through which calcium makes its way into the cells of blood vessel muscles. In this way, calcium-channel blockers prevent blood vessels from constricting.

Both beta-blockers and calcium-channel blockers are helpful in reducing recurrent heart attacks. Calcium-channel blockers, in particular, improve blood flow to the heart muscle by opening up the coronary arteries and making their diameter larger. [Read the Original Article]