Disorders of membrane channels or channelopathies.

Abstract

OBJECTIVE:

To review the structure and function of membrane ion channels with special emphasis on inherited nervous system channel disorders or channelopathies.

RESULTS:

Channels are pores in the cell membrane. Through these pores ions flow across the membrane and depolarize or hyperpolarize the cell. Channels can be classified into 3 types: non-gated, directly gated and second messenger gated channels. Among the important directly gated channels are voltage gated (Na(+), K(+), Ca(2+), Cl(-)) and ligand gated (ACh, Glutamate, GABA, Glycine) channels. Channels are macromolecular protein complexes within the lipid membrane. They are divided into distinct protein units called subunits. Each subunit has a specific function and is encoded by a different gene. The following inherited channelopathies are described. (1) Sodium channelopathies: familial generalized epilepsy with febrile seizures plus, hyperkalemic periodic paralysis, paramyotonias, hypokalemic periodic paralysis; (2) potassium channelopathies: benign infantile epilepsy, episodic ataxia type 1; (3) calcium channelopathies: episodic ataxia type 2, spinocerebellar ataxia type 6, familial hemiplegic migraine, hypokalemic periodic paralysis, central core disease, malignant hyperthermia syndrome, congenital stationary night blindness; (4) chloride channelopathies: myotonia congenitas; (5) ACh receptor channelopathies: autosomal dominant frontal lobe nocturnal epilepsy, congenital myasthenic syndromes; (6) glycine receptor channelopathies: hyperekplexia.

CONCLUSIONS:

Studies of human inherited channelopathies have clarified the functions of many ion channels. More than one gene may regulate a function in a channel, thus different genetic mutations may manifest with the same disorder. The complex picture of the genetic and molecular structures of channels will require frequent updates.

• Authors: G G Celesia
• Journal: Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology (Clin Neurophysiol) Vol. 112 Issue 1 Pg. 2-18 (Jan 2001) ISSN: 1388-2457 [Print] Netherlands
• PMID: 11137655 (Publication Type: Journal Article, Review)

Chemical References

• Ion Channels

Topics

• Animals
• Cell Membrane (metabolism, physiology)
• Humans
• Ion Channel Gating (physiology)
• Ion Channels (metabolism, physiology)