George J Juang

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BACKGROUND This study sought to define the technique and results of magnetic resonance imaging (MRI) of pulmonary vein (PV) anatomy before and after catheter ablation of atrial fibrillation (AF). METHODS AND RESULTS Twenty-eight patients with AF underwent ablation. Patients underwent gadolinium-enhanced MRI before and 6 weeks after their procedures. A(More)
Recent studies implicate increased cGMP synthesis as a postreceptor contributor to reduced cardiac sympathetic responsiveness. Here we provide the first evidence that modulation of this interaction by cGMP-specific phosphodiesterase PDE5A is also diminished in failing hearts, providing a novel mechanism for blunted beta-adrenergic signaling in this(More)
Heart failure (HF) is characterized by marked prolongation of action potential duration and reduction in cellular repolarization reserve. These changes are caused in large part by HF-induced K(+) current downregulation. Molecular mechanisms underlying these changes remain unclear. We determined whether downregulation of K(+) currents in a canine model of(More)
Myocardial NO signaling appears elevated in heart failure (HF). Whether this results from increased NO production, induction of the high-output NO synthase (NOS)2 isoform, or changes in NOS regulatory pathways (such as caveolae) remains controversial. We tested the hypothesis that increased abundance of caveolin-3 and/or sarcolemmal caveolae contribute to(More)
BACKGROUND The transient outward potassium current (I(to)) encoded by the Kv4 family of potassium channels is important in the repolarization of cardiac myocytes. KChIPs are a recently identified group of Ca2+-binding accessory subunits that modulate Kv4-encoded currents. KChIP2 is the only family member expressed in the heart. METHODS AND RESULTS We(More)
Heart failure (HF) is a complex disease that presents a major public health challenge to Western society. The prevalence of HF increases with age in the elderly population, and the societal disease burden will increase with prolongation of life expectancy. HF is initially characterized by an adaptive increase of neurohumoral activation to compensate for(More)
The transient outward potassium current (I(to)) is an important repolarizing current in the mammalian heart. I(to) is regulated by adrenergic stimulation; however, the effect of agonists on this current, and consequently the action potential duration and profile, is variable. An important source of the variability is the difference in the channel genes that(More)
(Na++K+)-ATPase (NKA) plays an important role in ion homeostasis and regulates cardiac contraction. To understand the molecular basis of its cardiac regulatory functions, we investigated whether the primary structure of the H1-H2 domain in alpha-1 (alpha1) subunit of the enzyme plays a role in myocardial contractile regulation. Here we show that(More)
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