Potassium Channels: Physiological Roles and Pathologies

This set of vocabulary flashcards covers the physiological roles of potassium channels in hearing, pancreatic function, neurodegeneration, and cardiac syndromes based on the lecture material.

Inter-aural time of arrival differences (ITD)

The extra distance that the sound has to travel to reach the second ear, used by the auditory system for sound localization.

Kv3.1 K+ channel

A potassium channel down-regulated during noise-exposed hearing loss and implicated in fusiform cell excitability changes after acoustic over exposure (AOE).

AUT-1

A Kv3.1 K+ channel opener used as a positive modulator to decrease synaptic activity and restore excitability in fusiform cells.

Kv7.4

A potassium channel that, along with Kv3.1, is down-regulated during age-related hearing loss.

High voltage-activated K+ channels

Includes channels like Kv3 and Kv2, which are involved in action potential repolarization and show fast kinetics.

Low voltage-activated K+ channels

Includes channels like Kv1, Kv4, and Kv7, which respond at the action potential threshold and show slow kinetics.

KCa channels

Calcium-activated potassium channels (including BK, IK, and SK channels) involved in neurodegenerative conditions like memory deficits and cell death.

KATP channel

A channel composed of four inwardly rectifying potassium channel ($Kir6.x$) subunits forming a central pore, surrounded by four regulatory sulphonylurea receptor ($SUR$) subunits.

Congenital hyperinsulinism

A condition most commonly caused by loss-of-function mutations in the $Kir6.2$ or $SUR1$ subunits of the pancreatic KATP channel.

Neonatal diabetes

A condition caused by gain-of-function mutations in $Kir6.2$ or $SUR1$, leadings to a shortage of insulin and hyperglycemia.

P-R interval

Records the electrical impulses traveling from the atria to the ventricles through the AV (atrium-ventricular) node.

QRS complex

The electrocardiogram component representing the rapid depolarization of the ventricles, leading to ventricular contraction.

T wave

The part of the ECG that corresponds to the repolarization of the ventricles.

QT interval

Measures the total time required for both ventricular depolarization and repolarization.

Romano-Ward syndrome

An autosomal dominant form of Long QT Syndrome associated with mutations in genes like KCNQ1 and KCNH2.

Jervell-Lange-Nielsen syndrome

An autosomal recessive form of Long QT Syndrome associated with mutations in KCNQ1 or KCNE1.

LQT1

A Long QT variant associated with the KCNQ1 gene, characterized by a decrease in K+ current, exercise triggers ($68\%$), and a penetrance of $62\%Inline$.

LQT2

A Long QT variant associated with the KCNH2/HERG gene, often triggered by emotional stress ($49\%$), with a penetrance of $75\%Inline$.

LQT3

A Long QT variant associated with the SCN5A gene (sodium channel), frequently triggered during sleep/repose ($64\%$), with high penetrance ($90\%Inline$).