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In excitable cells, such as neurons, the delayed counterflow of potassium ions shapes the action potential. By contributing to the regulation of the cardiac action potential duration in cardiac muscle, malfunction of potassium channels may cause life-threatening arrhythmias. Potassium channels may also be involved in maintaining vascular tone.
As an action potential (nerve impulse) travels down an axon there is a change in electric polarity across the membrane of the axon. In response to a signal from another neuron, sodium- (Na +) and potassium- (K +)–gated ion channels open and close as the membrane reaches its threshold potential.
Voltage-gated potassium channels (VGKCs) are transmembrane channels specific for potassium and sensitive to voltage changes in the cell's membrane potential. During action potentials , they play a crucial role in returning the depolarized cell to a resting state.
After a delay (known as the absolute refractory period), the action potential terminates as potassium channels open, allowing K + to leave the cell and causing the membrane potential to return to negative, this is known as repolarization.
The dysfunction of potassium channels, including SK channels, is thought to play a role in the pathogenesis of Parkinson's disease (PD), a progressive neurodegenerative disorder. SK channel blockers control the firing rate (the number of action potentials produced by a neuron in a given time) and the firing pattern (the way action potentials ...
At the peak action potential, K + channels open and the cell becomes (c) hyperpolarized. Voltage gated ion channels respond to changes in the membrane potential. Voltage gated potassium, chloride and sodium channels are key components in the generation of the action potential as well as hyper-polarization.
Afterhyperpolarization, or AHP, is the hyperpolarizing phase of a neuron's action potential where the cell's membrane potential falls below the normal resting potential. This is also commonly referred to as an action potential's undershoot phase. AHPs have been segregated into "fast", "medium", and "slow" components that appear to have distinct ...
This modulation of synaptic transmission and electrical discharge at the cellular level is due to BK channel expression in conjunction with other potassium-calcium channels. [10] The opening of these channels causes a drive towards the potassium equilibrium potential and thus play a role in speeding up the repolarization of action potentials ...