L-Calcium Channel Receptor Antagonists

The L-type calcium channel, whose pore is formed by the CACNA1C alpha-1C subunit, opens on membrane depolarisation and mediates influx of calcium into the cytoplasm, which in turn triggers calcium release from the sarcoplasm. It is the channel that couples excitation to contraction in the heart, is required for normal heart development and rhythm, and is required for contraction of smooth muscle in blood vessels and intestine and so for normal blood pressure regulation. Drugs in this class are predominantly L-type blockers - UniProt records the channel as inhibited by the dihydropyridines, naming isradipine and nifedipine - so their effect falls on cardiac and vascular tissue. Selectivity is not absolute across the class as constituted: the cited MED-RT list also contains mibefradil, whose defining property is T-type over L-type selectivity.