The properties of voltage-dependent Na channels modified by veratridine (VTD) were studied in voltage-clamped nodes of Ranvier of the frog Rana pipiens. Two modes of gating of VTD-modified channels are described. The first, occurring on a time scale of milliseconds, is shown to be the transition of channels between a modified resting state and a modified open state. There are important qualitat...

background: aim of this study is to evaluate the accuracy of the gated volumetric modulated arc therapy (vmat/rapidarc) using 2d planar dosimetry, dynalog files and compass 3d dosimetry system. materials and methods: pre-treatment quality assurance of 10 gated vmat plans was verified using 2d array and compass 3d dosimetry system. advantage of compass over 2d planar is that it provides the clin...

ATP-gated P2X2 channels undergo permeability changes through a process that is incompletely understood. In the present study, we used fluorescence resonance energy transfer (FRET) and electrophysiology to measure cytosolic gating motions in P2X2 channels as they enter a state with increased permeability. P2X2 channels underwent permeability changes with a time course that was similar to decreas...

Voltage-dependent gating was investigated in a recombinant human skeletal muscle Cl- channel, hCIC-1, heterologously expressed in human embryonic kidney (HEK-293) cells. Gating was found to be mediated by two qualitatively distinct processes. One gating step operates on a microsecond time scale and involves the rapid rearrangement of two identical intramembranous voltage sensors, each consistin...

We investigated the contribution of the putative inactivation lid in voltage-gated sodium channels to gating charge immobilization (i.e., the slow return of gating charge during repolarization) by studying a lid-modified mutant of the human heart sodium channel (hH1a) that had the phenylalanine at position 1485 in the isoleucine, phenylalanine, and methionine (IFM) region of the domain III-IV l...

The aim of the present study was to investigate the single-channel properties of different gating modes in the native human cardiac Na+ channel. Patch-clamp experiments were performed at low noise using ultrathick-walled pipettes. In 17 cell-attached patches containing only one channel, fast back and forth switching between five different Na+-channel gating modes (F-mode, M1-mode, M2-mode, S-mo...

We have characterized the effects of prepulse hyperpolarization and extracellular Mg(2+) on the ionic and gating currents of the Drosophila ether-à-go-go K(+) channel (eag). Hyperpolarizing prepulses significantly slowed channel opening elicited by a subsequent depolarization, revealing rate-limiting transitions for activation of the ionic currents. Extracellular Mg(2+) dramatically slowed acti...

Mouse cardiac MR gating using ECG is affected by the hostile MR environment. It requires appropriate signal processing and correct QRS detection, but gating software methods are currently limited. In this study we sought to demonstrate the feasibility of digital real-time automatically updated gating methods, based on optimizing a signal-processing technique for different mouse strains. High-re...

Introduction The navigator gating technique reduced respiratory motion artifacts and is suited to abdominal MRI with patients who have difficulty in breath-holding. The motion adapted gating (MAG) approach [1] employs varying gating threshold depending on phase encoding steps, which accelerates gating to reduce scan time. However, even the MAG approach results in considerably longer scan time c...

Various ClC-type voltage-gated chloride channel isoforms display a double barrel topology, and their gating mechanisms are thought to be similar. However, we demonstrate in this work that the nearly ubiquitous ClC-2 shows significant differences in gating when compared with ClC-0 and ClC-1. To delineate the gating of ClC-2 in quantitative terms, we have determined the voltage (V(m)) and time de...