Inactivation voltage-dependence

Conforti L, Millhorn DE (1997) Selective inhibition of a slow-inactivating voltage-dependent K+ channel in rat PC12 cells by hypoxia. J Physiol 502 293-305... 

Conforti L, Millhom DE. Selective inhibition of a slow-inactivating voltage-dependent... 

Conforti L, Millhom DE. Selective inhibition of a slow-inactivating voltage-dependent K channel in rat PC12 cells by hypoxia. J Physiol (Lend) 1997 502(Pt 2) 293-305. Hulme JT, Coppock EA, Felipe A, Martens JR, Tamkun MM. Oxygen sensitivity of cloned voltage-gated channels expressed in the pulmonary vasculature. Circ Res 1999 85(6) 489 97. 

A shift of the voltage-dependence of inactivation to a hyperpolarizing direction, resulting in a lower fraction of channels available for activation at action potential threshold. 

An increase in [Na+]j can also regulate the Na+/Ca2+ exchanger. In particular, when intracellular Na+ increases, it binds to the transport site of the exchanger molecule, and after this Na+ influx, an inactivation process of the exchanger occurs. This inactivation process, very similar to the phenomenon occurring in voltage-dependent ionic channels, is named... 

Synaptic Transmission. Figure 1 Synaptic transmission. The presynaptic terminal contains voltage-dependent Na Superscript and Ca2+ channels, vesicles with a vesicular neurotransmitter transporter VNT, a plasmalemmal neurotransmitter transporter PNT, and a presynaptic G protein-coupled receptor GPCR with its G protein and its effector E the inset also shows the vesicular H+ pump. The postsynaptic cell contains two ligand-gated ion channels LGIC, one for Na+ and K+ and one for Cl-, a postsynaptic GPRC, and a PNT. In this synapse, released transmitter is inactivated by uptake into cells. 

Voltage-dependent inactivation is channel inactivation at depolarised membrane potentials. 

Go—inhibits voltage-dependent Ca + and K+ channels (inactivated by Pertussis toxin)... 

The Ca channels that have been the most extensively studied are the voltage-dependent Ca channels. These channels are usually found in plasma or transverse tubule membranes. Voltage-dependent Ca channels open in response to an appropriate membrane depolarization. Several different types of voltage-dependent Ca channels have been described and are characterized by differences in their activation and inactivation sensitivities to voltage, their kinetic properties, and their sensitivities to activation or inhibition by a variety of pharmacological agents. 

Voltage-dependent activation requires moving charges 105 The fast inactivation gate is on the inside 106... 

There are at least five different types of voltage-dependent Ca2+ channel molecules, differing in their gating kinetics, modes of Ca2+-inactivation and Ca2+-iregulation, and sensitivity to specific marine toxins [13] (see Ch. 6). The distinctions between the types of channel are of considerable interest because the different subtypes are believed to subserve different cellular functions. For example, the control of neurotransmitter release in peripheral sympathetic neurons appears to be under the predominant control of N-type calcium channels. 

Nelson There is an emerging theme of calmodulin being tightly bound to almost all its targets. For example, the SK channel is gated by calmodulin, and is extremely tightly bound. Another example is the voltage-dependent Ca2+ channel, where calmodulin is also bound and involved in inactivation. 

Further support for a link between voltage-dependent Ca2+ channel activity and KCa channel activity was the present observation that during a depolarization (after 200 ms) the time course of change in the open probability of Kca channels was similar to that of Ica as it inactivated. Since KCa channels themselves do not exhibit voltage-dependent inactivation at OmV, the reduction in the open probability of the channel presumably reflects... 

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