How do calcium channel blockers work?

Calcium channel blockers function by inhibiting the entry of calcium ions into cells through voltage-gated calcium channels, particularly in the smooth muscle of blood vessels and the heart. This mechanism leads to relaxation of the smooth muscle, resulting in vasodilation, which can help to lower blood pressure. Additionally, by reducing calcium influx in cardiac muscle cells, calcium channel blockers can decrease heart contractility and lower heart rate, further contributing to their antihypertensive effects. The overall outcome is a reduction in cardiac workload and blood pressure, making them effective in the treatment of conditions such as hypertension and angina.

The other options do not describe the mechanism of action for calcium channel blockers accurately. They do not increase calcium levels in the blood or stimulate calcium release from bones, nor do they have any direct action on potassium channels. Instead, their primary action centers around the regulation of calcium entry into cells, which directly influences vascular and cardiac function.