Depolarization


Depolarization

In biology, depolarization is a change in a cell's membrane potential, making it more positive, or less negative. In neurons and some other cells, a large enough depolarization may result in an action potential. Hyperpolarization is the opposite of depolarization, and inhibits the rise of an action potential.

Contents

Mechanism

If, for example, a cell has a resting potential of -70mV, once the membrane potential changes to -50mV, then the cell has been depolarized. Depolarization is often caused by influx of cations, e.g. Na+ through Na+ channels, or Ca2+ through Ca2+ channels. On the other hand, efflux of K+ through K+ channels inhibits depolarization, as does influx of Cl (an anion) through Cl channels. If a cell has K+ or Cl currents at rest, then inhibition of those currents will also result in a depolarization.

Because depolarization is a change in membrane voltage, electrophysiologists measure it using current clamp techniques. In voltage clamp, the membrane currents giving rise to depolarization are either an increase in inward current, or a decrease in outward current.

Depolarization blockers

There are drugs, called depolarization blocking agents, that inhibit depolarization, e.g. by blocking the channels responsible for depolarization, or by opening K+ channels. Examples include the nicotinic agonists suxamethonium and decamethonium.[1]

References

  1. ^ Rang, H. P. (2003). Pharmacology. Edinburgh: Churchill Livingstone. ISBN 0-443-07145-4.  Page 149

External links


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Look at other dictionaries:

  • Depolarization — De*po lar*i*za tion, n. [Cf. F. d[ e]polarisation.] The act of depriving of polarity, or the result of such action; reduction to an unpolarized condition. [1913 Webster] {Depolarization of light} (Opt.), a change in the plane of polarization of… …   The Collaborative International Dictionary of English

  • Depolarization — Depolarization. См. Деполяризация. (Источник: «Металлы и сплавы. Справочник.» Под редакцией Ю.П. Солнцева; НПО Профессионал , НПО Мир и семья ; Санкт Петербург, 2003 г.) …   Словарь металлургических терминов

  • depolarization — 1815; see DE (Cf. de ) + POLARIZATION (Cf. polarization). Related: Depolarize; depolarized …   Etymology dictionary

  • depolarization — (Amer.) n. act of removing polarity; loss of polarity (also depolarisation) …   English contemporary dictionary

  • depolarization — 1. A relative reduction in magnitude of polarization; in nerve cells, d. may result from an increase in the permeability of the cell membrane to sodium ions. 2. The destruction, neutralization, or change in direction of …   Medical dictionary

  • depolarization — n. the sudden surge of charged particles across the membrane of a nerve cell or a muscle cell that accompanies a physicochemical change in the membrane and cancels out, or reverses, its resting potential to produce an action potential. The… …   The new mediacal dictionary

  • depolarization — depoliarizacija statusas T sritis chemija apibrėžtis Elektrodo poliarizacijos sumažėjimas. atitikmenys: angl. depolarization rus. деполяризация …   Chemijos terminų aiškinamasis žodynas

  • depolarization — depoliarizacija statusas T sritis fizika atitikmenys: angl. depolarization vok. Depolarisation, f rus. деполяризация, f pranc. dépolarisation, f …   Fizikos terminų žodynas

  • depolarization — depoliarizavimas statusas T sritis fizika atitikmenys: angl. depolarization vok. Depolarisierung, f rus. деполяризирование, n pranc. dépolarisation, f …   Fizikos terminų žodynas

  • depolarization — noun see depolarize …   New Collegiate Dictionary


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