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Hyperpolarization is a change in a cell's membrane potential that makes it more negative. Cells typically have a negative resting potential, with neuronal action potentials depolarizing the membrane. Cells typically have a negative resting potential, with neuronal action potentials depolarizing the membrane.
Hyperpolarization has several meanings: Hyperpolarization (biology) occurs when the strength of the electric field across the width of a cell membrane increases Hyperpolarization (physics) is the selective polarization of nuclear spin in atoms far beyond normal thermal equilibrium
HCN4 is the main isoform expressed in the sinoatrial node, but low levels of HCN1 and HCN2 have also been reported.The current through HCN channels, called the pacemaker current (I f), plays a key role in the generation and modulation of cardiac rhythmicity, [13] as they are responsible for the spontaneous depolarization in pacemaker action potentials in the heart.
Schematic of an electrophysiological recording of an action potential, showing the various phases that occur as the voltage wave passes a point on a cell membrane.The afterhyperpolarisation is one of the processes that contribute to the refractory period.
Threshold decrease is evident during extensive depolarization, and threshold increase is evident with extensive hyperpolarization. With hyperpolarization, there is an increase in the resistance of the internodal membrane due to closure of potassium channels, and the resulting plot "fans out".
Based on current evidence, the term of endothelium-derived hyperpolarising factor should represent a mechanism rather than a specific factor. The mechanism(s) of endothelium-dependent hyperpolarization (i.e., EDHF-mediated relaxation) seems to be heterogeneous depending on several factors (e.g., size and vascular bed), surrounding environment ...
The hyperpolarization following an inhibitory stimulus causes a further decrease in voltage within the neuron below the resting potential. By hyperpolarizing a neuron, an inhibitory stimulus results in a greater negative charge that must be overcome for depolarization to occur.
Slow afterhyperpolarisation (sAHP) refers to prolonged periods of hyperpolarisation in a neuron or cardiomyocyte following an action potential or other depolarising event. In neurons, trains of action potentials may be required to induce sAHPs; this is unlike fast AHPs that require no more than a single action potential.