Calcium channel blockers are a class of drugs and natural substances that disrupt the conduction of calcium channels. It has effects on many excitable cells of the body, such as cardiac muscle, i.e. heart, smooth muscles of blood vessels, or neurons. The main clinical usage of calcium channel blockers is to decrease blood pressure. It is for this action that they are used in individuals with hypertension. Visit CardioSmart. Org to learn more about Calcium channel blockers.