The L-type calcium channel
is a type of voltage-dependent calcium channel
Voltage-dependent calcium channels are a group of voltage-gated ion channels found in excitable cells with a permeability to the ion Ca2+...
. "L" stands for long-lasting referring to the length of activation. Like the others of this class, the α1 subunit is the one that determines most of the channel's properties.
L-type calcium channel blocker
A calcium channel blocker is a chemical that disrupts the movement of calcium through calcium channels.CCB drugs devised to target neurons are used as antiepileptics. However, the most widespread clinical usage of calcium channel blockers is to decrease blood pressure in patients with...
drugs are used as cardiac antiarrhythmics or antihypertensives, depending on whether the drugs have higher affinity for the heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
(the phenylalkylamines, like verapamil
Verapamil is an L-type calcium channel blocker of the phenylalkylamine class. It has been used in the treatment of hypertension, angina pectoris, cardiac arrhythmia, and most recently, cluster headaches. It is also an effective preventive medication for migraine...
), or for the vessels (the dihydropyridines
Dihydropyridine is a molecule based upon pyridine, and the parent of a class of molecules that have been semi-saturated with two substituents replacing one double bond. They are particularly well known in pharmacology as L-type calcium channel blockers....
, like nifedipine
Nifedipine is a dihydropyridine calcium channel blocker...
L-type channels are selectively blocked by benzothiazepines (like diltiazem
Diltiazem is a non-dihydropyridine member of the class of drugs known as calcium channel blockers, used in the treatment of hypertension, angina pectoris, and some types of arrhythmia....
- Cardiac action potential#Major currents
In skeletal muscle, there is a very high concentration of DHP
receptors, representing L-type calcium channels, situated in
the T-tubules. Muscle depolarization results in large gating
currents, but anomalously low calcium flux, which is now
explained by the very slow activation of the ionic currents. For
this reason, little or no Ca2+
passes across the T-tubule
membrane during a single action potential.