Article Abstract:
A major subunit of the cardiac IKr potassium channel is encoded by human ether-a-go-go-related gene (HERG). HERG, when expressed in Xenopus oocytes, shows biophysical characteristics similar to the rapidly activating delayed rectifier potassium current (IKr) in cardiac myocytes. The HERG current has been found to be selective for potassium, and a decline in the current is seen at depolarizations above 0 mV. Extracellular potassium ions can activate this current. Lanthanum and cobalt inhibit the HERG current. The results suggest a mechanistic connection between inherited and acquired forms of long QT syndrome, which causes cardiac arrhythmias.
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Article Abstract:
A study of the mutation involved in inherited cardiac arrhythmia through genotypic analyses reveals that the SCN5A mutations are linked to LQT3 in three families. SCN5A is the gene that encodes the cardiac sodium channel. Similar intragenic deletions of SCN5A are observed through DNA sequence analyses and single strand conformation polymorphism in members of two unrelated families. A region that is essential for channel inactivation houses the mutations, indicating a possible cellular pathway for chromosome-3-linked LQT.
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Article Abstract:
Timothy syndrome, a novel disorder characterized by multiorgan dysfunction including lethal arrhythmias, webbing of fingers and toes, congenital heart disease, immune deficiency, intermittent hypoglycemia, cognitive abnormalities, and autism is reported. The Cav1.2 the cardiac L-type calcium channel is important for excitation and contraction of the heart.
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