How do calcium channel blockers exert their effects?

Calcium channel blockers exert their effects primarily by blocking the entry of calcium into cardiac tissue. This is fundamental because calcium plays a crucial role in the contraction of cardiac and smooth muscle cells. When calcium channels are inhibited, there is a reduced influx of calcium ions during depolarization, leading to decreased myocardial contractility and vasodilation. This action lowers the workload on the heart and can help manage conditions such as hypertension and angina.

The mechanism is particularly important in the cardiac and vascular systems since the calcium-dependent processes are vital for muscle contraction and vascular tone. By inhibiting these channels, calcium channel blockers not only decrease heart rate and myocardial oxygen demand but also facilitate relaxation of the vascular smooth muscle, leading to a reduction in blood pressure.