Topic
Ion channel
About: Ion channel is a research topic. Over the lifetime, 12737 publications have been published within this topic receiving 661698 citations. The topic is also known as: ion channel & ion channel complex.
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16 Jul 2001
TL;DR: The superfamily of voltage-gated channels was studied in this paper, where a classical biophysics of the squid giant axon was discussed. But the superfamily was not considered in this paper.
Abstract: PART I Classical biophysics of the squid giant axon The superfamily of voltage-gated channels Voltage-gated calcium channels Potassium channels and chloride channels Ligand-gated channels of fast chemical synapses Modulation, slow synaptic action, and second messengers Sensory transduction and excitable cells Calcium dynamics, epithelial transport, and intercellular coupling PART II Elementary properties of ions in solution Elementary properties of pores Counting channels Structure of channel proteins Selective permeability: Independence Selective permeability: Saturation and binding Classical mechanisms of block Structure-function studies of permeation and block Gating mechanisms: Kinetic thinking Gating: Voltage sensing and inactivation Modification of gating in voltage-sensitive channels Cell biology and channels Evolution and origins
3,678 citations
TL;DR: It is shown that an electric field can drive single-stranded RNA and DNA molecules through a 2.6-nm diameter ion channel in a lipid bilayer membrane, which could in principle provide direct, high-speed detection of the sequence of bases in single molecules of DNA or RNA.
Abstract: We show that an electric field can drive single-stranded RNA and DNA molecules through a 2.6-nm diameter ion channel in a lipid bilayer membrane. Because the channel diameter can accommodate only a single strand of RNA or DNA, each polymer traverses the membrane as an extended chain that partially blocks the channel. The passage of each molecule is detected as a transient decrease of ionic current whose duration is proportional to polymer length. Channel blockades can therefore be used to measure polynucleotide length. With further improvements, the method could in principle provide direct, high-speed detection of the sequence of bases in single molecules of DNA or RNA.
3,251 citations
01 Jan 1996
TL;DR: The action potential is triggered when the membrane potential, which was at the resting level, depolarizes and reaches the threshold of excitation, which triggers the action potential.
Abstract: Excitability. Excitability of cell membranes is crucial for signaling in many types of cell. Excitation in the physiological sense means that the cell membrane potential undergoes characteristic changes which, in most cases, go in the depolarizing direction. Single depolarization from the resting potential to potentials near 0 mV has generally been called an action potential. A schematic representation of a neuronal action potential is given in Fig. 12.1 A. The action potential is triggered when the membrane potential, which was at the resting level, depolarizes and reaches the threshold of excitation. This depolarization, which triggers the action potential, is generated by depolarizing synaptic currents, or depolarizing current coming from a membrane region that is already excited (propagation of an action potential), or by pacemaker currents mediated by pacemaker channels, or by current injected externally by an electrode. The duration of different types of action potential varies from seconds to less than 1 ms.
3,016 citations
TL;DR: Using voltage-clamp experiments on mouse spinal cord neurones, it is shown that the voltage-sensitivity of NMDA action is greatly reduced on the withdrawal of physiological concentrations (∼1 mM) of Mg2+ from the extracellular fluid, providing further evidence that Mg 2+ blocks inward current flow through ion channels linked to NMDA receptors.
Abstract: Acidic amino acids are putative excitatory synaptic transmitters1,2, the ionic mechanism of which is not well understood. Recent studies with selective agonists and antagonists suggest that neurones of the mammalian central nervous system possess several different receptors for acidic amino acids3,4, which in turn are coupled to separate conductance mechanisms5. N-methyl-D-aspartic acid (NMDA) is a selective agonist for one of these receptors3,4. The excitatory action of amino acids acting at NMDA receptors is remarkably sensitive to the membrane potential and it has been suggested that the NMDA receptor is coupled to a voltage-sensitive conductance6–9. Recently, patch-clamp experiments have shown the voltage-dependent block by Mg2+ of current flow through ion channels activated by L-glutamate10. We now show using voltage-clamp experiments on mouse spinal cord neurones that the voltage-sensitivity of NMDA action is greatly reduced on the withdrawal of physiological concentrations (∼1 mM) of Mg2+ from the extracellular fluid. This provides further evidence that Mg2+ blocks inward current flow through ion channels linked to NMDA receptors.
2,810 citations
TL;DR: P2X receptors are membrane ion channels that open in response to the binding of extracellular ATP and are involved in the initiation of afferent signals in several viscera and play a key role in sensing tissue-damaging and inflammatory stimuli.
Abstract: P2X receptors are membrane ion channels that open in response to the binding of extracellular ATP. Seven genes in vertebrates encode P2X receptor subunits, which are 40–50% identical in amino acid ...
2,800 citations