Calcium channels are a class of voltage-gated ion channels that open in response to changes in the electrical potential across the cell membrane and allow the influx of positively charged calcium ions (Ca2+) into the cell. This influx of ions is critical in regulating muscle contraction, neurotransmitter release, and gene expression.

Calcium channels are found in various cell types, including muscle cells, nerve cells, and endocrine cells. They are critical in regulating muscle contraction, neurotransmitter release, and insulin secretion.

The dysregulation of calcium channels has been linked to a wide range of diseases, including cardiovascular disorders, neurological disorders, and metabolic disorders. For example, mutations in calcium channels have been linked to hypertension, arrhythmias, and atrial fibrillation. Calcium channels also regulate insulin secretion, and defects in calcium channels have been linked to diabetes.

Calcium channels are also important drug targets for various diseases. For example, blockers of specific calcium channels have been used to treat hypertension and certain arrhythmias. In addition, activators of calcium channels have been proposed as potential therapies for diabetes and other metabolic disorders.

Calcium channel blockers, also known as calcium antagonists, are drugs that inhibit the influx of calcium ions into cells and are used to treat hypertension and angina pectoris. They have also been used to treat certain types of arrhythmias and migraines.