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Inwardly rectifying potassium channels are important in cellular repolarization of many excitable tissues. Amino acid sequence alignment of different mammalian inward rectifier K(+) channels revealed two absolutely conserved cysteine residues in the putative extracellular face, suggesting a possible disulfide bond. Replacement of these cysteine residues in(More)
The aim of the present study was to compare the biophysical properties and Cd2+ sensitivity of Kv4.2 and Kv1.4 in Xenopus oocytes with those of native transient outward potassium currents in rat and rabbit ventricular myocytes. In Xenopus oocytes, Kv4.2 inactivated at hyperpolarized voltages (V(1/2)inact = -58.4 +/- 0.96 mV, n = 12) and recovered from(More)
Heart failure is the leading cause of mortality in patients with transfusional iron (Fe) overload in which myocardial iron uptake ensues via a transferrin-independent process. We examined the ability of L-type Ca2+ channel modifiers to alter Fe2+ uptake by isolated rat hearts and ventricular myocytes. Perfusion of rat hearts with 100 nmol/L 59Fe2+ and 5(More)
Voltage-gated K(+) (Kv) 2.1 is the dominant Kv channel that controls membrane repolarization in rat islet beta-cells and downstream insulin exocytosis. We recently showed that exocytotic SNARE protein SNAP-25 directly binds and modulates rat islet beta-cell Kv 2.1 channel protein at the cytoplasmic N terminus. We now show that SNARE protein syntaxin 1A(More)
We have examined the effects of a beta-scorpion toxin purified from the venom of the Venezuelan scorpion Tityus discrepans, TdVIII, on heterologously expressed rat skeletal muscle Na+ channels (rSkM1). TdVIII (100 nM) produced a leftward shift in the voltage dependence of activation and reduced the peak Na+ conductance of rSkM1 channels coexpressed with the(More)
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Action potential prolongation is a common finding in human heart failure and in animal models of cardiac hypertrophy. The mechanism of action potential prolongation involves altered expression of a variety of depolarising and hyperpolarising currents in the myocardium. In particular, decreased density of the transient outward potassium current seems to play(More)
We examined the ability of local anesthetics to correct altered inactivation properties of rat skeletal muscle Na+ channels containing the equine hyperkalemic periodic paralysis (eqHPP) mutation when expressed in Xenopus oocytes. Increased time constants of current decay in eqHPP channels compared with wild-type channels were restored by 1 mM benzocaine but(More)
Members of the family C receptors within the G-protein coupled receptor superfamily include the metabotropic glutamate receptors, GABA(B) receptors, the calcium-sensing receptor (CaSR), the V2R pheromone receptors, the T1R taste receptors, and a small group of uncharacterized orphan receptors. We have cloned and studied the mouse GPRC6A family C orphan(More)
Voltage-dependent (Kv) outward K(+) currents repolarize beta-cell action potentials during a glucose stimulus to limit Ca(2+) entry and insulin secretion. Dominant-negative "knockout" of Kv2 family channels enhances glucose-stimulated insulin secretion. Here we show that a putative Kv2.1 antagonist (C-1) stimulates insulin secretion from MIN6 insulinoma(More)