Target type: molecularfunction
Enables the transmembrane transfer of a calcium ion by a voltage-gated channel across the plasma membrane of a bundle of His cardiac muscle cell that contributes to the depolarization phase of an action potential. A voltage-gated channel is a channel whose open state is dependent on the voltage across the membrane in which it is embedded. [GOC:BHF, GOC:mtg_cardiac_conduct_nov11]
Voltage-gated calcium channels (VGCCs) play a crucial role in the action potential of His bundle cells, which are specialized cardiac muscle cells that conduct electrical impulses from the atria to the ventricles. Specifically, L-type VGCCs, also known as Cav1.2 channels, are responsible for the slow inward calcium current (ICaL) during the plateau phase of the His bundle cell action potential. This calcium influx is essential for several key functions:
1. **Depolarization and Action Potential Prolongation:** The entry of calcium ions through L-type VGCCs contributes to the depolarization of the His bundle cell membrane, prolonging the action potential duration. This extended depolarization is crucial for effective conduction of the electrical impulse to the ventricles.
2. **Calcium-Induced Calcium Release (CICR):** Calcium influx through L-type VGCCs triggers the release of even larger amounts of calcium from intracellular stores, specifically the sarcoplasmic reticulum (SR). This CICR mechanism amplifies the calcium signal, leading to a robust increase in intracellular calcium concentration.
3. **Muscle Contraction:** The elevated intracellular calcium concentration activates the contractile proteins, actin and myosin, leading to the contraction of the His bundle cells. This contraction is essential for the efficient propagation of the electrical impulse throughout the heart.
4. **Regulation of Heart Rate:** The activity of L-type VGCCs in His bundle cells is influenced by various factors, including neurotransmitters and hormones. This modulation plays a role in regulating heart rate and rhythm.
In summary, voltage-gated calcium channel activity, particularly the L-type VGCCs, is critical for the proper functioning of His bundle cells by contributing to action potential prolongation, calcium-induced calcium release, muscle contraction, and regulation of heart rate.'
"
| Protein | Definition | Taxonomy |
|---|---|---|
| Voltage-dependent calcium channel subunit alpha-2/delta-1 | A voltage-dependent calcium channel subunit alpha-2/delta-1 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P54289] | Homo sapiens (human) |
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| tacrine | tacrine : A member of the class of acridines that is 1,2,3,4-tetrahydroacridine substituted by an amino group at position 9. It is used in the treatment of Alzheimer's disease. Tacrine: A cholinesterase inhibitor that crosses the blood-brain barrier. Tacrine has been used to counter the effects of muscle relaxants, as a respiratory stimulant, and in the treatment of Alzheimer's disease and other central nervous system disorders. | acridines; aromatic amine | EC 3.1.1.7 (acetylcholinesterase) inhibitor |
| nimodipine | nimodipine : A dihydropyridine that is 1,4-dihydropyridine which is substituted by methyl groups at positions 2 and 6, a (2-methoxyethoxy)carbonyl group at position 3, a m-nitrophenyl group at position 4, and an isopropoxycarbonyl group at position 5. An L-type calcium channel blocker, it acts particularly on cerebral circulation, and is used both orally and intravenously for the prevention and treatment of subarachnoid hemorrhage from ruptured intracranial aneurysm. Nimodipine: A calcium channel blockader with preferential cerebrovascular activity. It has marked cerebrovascular dilating effects and lowers blood pressure. | 2-methoxyethyl ester; C-nitro compound; dicarboxylic acids and O-substituted derivatives; diester; dihydropyridine; isopropyl ester | antihypertensive agent; calcium channel blocker; cardiovascular drug; vasodilator agent |
| reboxetine | Reboxetine: A morpholine derivative that is a selective and potent noradrenaline reuptake inhibitor; it is used in the treatment of DEPRESSIVE DISORDER. | aromatic ether | |
| np 118809 | 1-(4-benzhydrylpiperazin-1-yl)-3,3-diphenylpropan-1-one: an N-type calcium channel blocker; structure in first source | ||
| pregabalin | pregabalin : A gamma-amino acid that is gamma-aminobutyric acid (GABA) carrying an isobutyl substitutent at the beta-position (the S-enantiomer). Binds with high affinity to the alpha2-delta site (an auxiliary subunit of voltage-gated calcium channels) in central nervous system tissues. Pregabalin: A gamma-aminobutyric acid (GABA) derivative that functions as a CALCIUM CHANNEL BLOCKER and is used as an ANTICONVULSANT as well as an ANTI-ANXIETY AGENT. It is also used as an ANALGESIC in the treatment of NEUROPATHIC PAIN and FIBROMYALGIA. | gamma-amino acid | anticonvulsant; calcium channel blocker |
| ith 4012 |