2,619 research outputs found
A possible cellular mechanism of neuronal loss in the dorsal root ganglia of dystonia musculorum (dt) mice.
No full textAmperometric Detection of Cysteine at an In+3 Stabilized Indium Hexacyanoferrate Modified Electrode
No full textEnhanced Electrodeposition of Indium Hexacyanoferrate Thin Films through Improved Plating Solution Stability
No full textA possible cellular mechanism of neuronal loss in the dorsalroot ganglia of Dystonia musculorum (dt) mice.
No full text
Leading chiral logarithms of KS→γγ and KS→γl+l− at two loops
No full textAbstractWe obtain the leading divergences at two-loop order for the decays KS→γγ and KS→γl+l− using only one-loop diagrams. We then find the double chiral logarithmic corrections to the decay branching ratio of KS→γγ and to the decay rate for KS→γl+l−. It turns out that these effects are numerically small and therefore make a very small enhancement on the branching ratio and decay rate. We also derive an expression for the corrections of type logμ×LEC. Numerical analysis done for the process KS→γγ shows that these single logarithmic effects can be sizable but come with opposite signs with respect to the double chiral logarithms
Abnormal cellular translocation of α-Internexin in spinal motor neurons of dystonia musculorum mice.
No full textAdult Ventricular Myocytes Segregate KCNQ1 and KCNE1 to Keep the <i>I</i> <sub>Ks</sub> Amplitude in Check Until When Larger <i>I</i> <sub>Ks</sub> Is Needed
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Background—
KCNQ1 and KCNE1 assemble to form the slow delayed rectifier (
I
Ks
) channel critical for shortening ventricular action potentials during high β-adrenergic tone. However, too much
I
Ks
under basal conditions poses an arrhythmogenic risk. Our objective is to understand how adult ventricular myocytes regulate the
I
Ks
amplitudes under basal conditions and in response to stress.
Methods and Results—
We express fluorescently tagged KCNQ1 and KCNE1 in adult ventricular myocytes and follow their biogenesis and trafficking paths. We also study the distribution patterns of native KCNQ1 and KCNE1, and their relationship to
I
Ks
amplitudes, in chronically stressed ventricular myocytes, and use COS-7 cell expression to probe the underlying mechanism. We show that KCNQ1 and KCNE1 are both translated in the perinuclear region but traffic by different routes, independent of each other, to their separate subcellular locations. KCNQ1 mainly resides in the jSR (junctional sarcoplasmic reticulum), whereas KCNE1 resides on the cell surface. Under basal conditions, only a small portion of KCNQ1 reaches the cell surface to support the
I
Ks
function. However, in response to chronic stress, KCNQ1 traffics from jSR to the cell surface to boost the
I
Ks
amplitude in a process depending on Ca binding to CaM (calmodulin).
Conclusions—
In adult ventricular myocytes, KCNE1 maintains a stable presence on the cell surface, whereas KCNQ1 is dynamic in its localization. KCNQ1 is largely in an intracellular reservoir under basal conditions but can traffic to the cell surface and boost the
I
Ks
amplitude in response to stress.
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Characterization of recombinant human cardiac KCNQ1/KCNE1 channels (I Ks) stably expressed in HEK 293 cells
No full textThe present study was designed to characterize pharmacological, biophysical and electrophysiological properties of the recombinant human cardiac I Ks (KCNQ1/KCNE1) channels at physiological temperature. Human cardiac KCNQ1 and KCNE1 genes were cotransfected into HEK 293 cells, and a cell clone stably expressing both genes was selected. Membrane currents were recorded using a perforated patch-clamp technique. The typical I Ks was slowly activated upon depolarization voltages in HEK 293 cells stably expressing human cardiac KCNQ1 and KCNE1 genes, and the current was inhibited by I Ks blockers HMR 1556 and chromanol 293B, with 50% inhibitory concentrations (IC 50s) of 83.8 nM and 9.2 μM, respectively. I Ks showed a significant temperature-dependent increase in its magnitude upon elevating bath temperature to 36°C from room temperature (21°C). The current was upregulated by the β-adrenoceptor agonist isoproterenol, and the effect was reversed by H89. In addition, I Ks was inhibited by Ba 2+ in a concentration-dependent manner (IC 50 = 1.4 mM). Action potential clamp revealed a "bell-shaped" time course of I Ks during the action potential, and maximal peak current was seen at the plateau of the action potential. A significant use- and frequency-dependent increase of I Ks was observed during a train of action potential clamp. These results indicate that the recombinant human cardiac I Ks stably expressed in HEK 293 cells is similar to native I Ks in drug sensitivity and regulated by Ba 2+ and β-adrenoceptor via the cyclic adenosine monophosphate/protein kinase A pathway. Importantly, the current exhibits significant temperature dependence, a bell-shaped time course during action potential and prominent use- or frequency-dependent accumulation during a train of action potentials. © Springer Science+Business Media, Inc. 2006.link_to_subscribed_fulltex
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