Nox2 and Nox4 influence neonatal c-kit(+) cardiac precursor cell status and differentiation.

Redox status has emerged as critical in modulating stemness and lineage commitment in several precursor cell types. However, a role for redox genes, specifically NADPH oxidases (Nox), in cardiac precursor cells (CPCs) has not been established. We tested whether CPCs marked by type III receptor tyrosine kinase c-kit (c-kit(+)) exhibit a unique NADPH oxidase signature that confers precursor status and whether alterations in this profile are functionally linked to changes in lineage specification.

In vivo bioluminescence imaging reveals redox-regulated activator protein-1 activation in paraventricular nucleus of mice with renovascular hypertension.

Renovascular hypertension in mice is characterized by an elevation in hypothalamic angiotensin II levels. The paraventricular nucleus (PVN) is a major cardioregulatory site implicated in the neurogenic component of renovascular hypertension. Increased superoxide (O(2)(-·)) production in the PVN is involved in angiotensin II-dependent neurocardiovascular diseases such as hypertension and heart failure.

Adenoviral delivery of VEGF121 early in pregnancy prevents spontaneous development of preeclampsia in BPH/5 mice.

An imbalance in circulating proangiogenic and antiangiogenic factors is postulated to play a causal role in preeclampsia (PE). We have described an inbred mouse strain, BPH/5, which spontaneously develops a PE-like syndrome including late-gestational hypertension, proteinuria, and poor feto-placental outcomes. Here we tested the hypothesis that an angiogenic imbalance during pregnancy in BPH/5 mice leads to the development of PE-like phenotypes in this model.

Silencing nox4 in the paraventricular nucleus improves myocardial infarction-induced cardiac dysfunction by attenuating sympathoexcitation and periinfarct apoptosis.

Rationale: Myocardial infarction (MI)-induced heart failure is characterized by central nervous system-driven sympathoexcitation and deteriorating cardiac function. The paraventricular nucleus (PVN) of the hypothalamus is a key regulator of sympathetic nerve activity and is implicated in heart failure. Redox signaling in the PVN and other central nervous system sites is a primary mechanism of neuro-cardiovascular regulation, and excessive oxidant production by activation of NADPH oxidases (Noxs) is implicated in some neuro-cardiovascular diseases.

Superoxide scavenging and Akt inhibition in myocardium ameliorate pressure overload-induced NF-κB activation and cardiac hypertrophy.

Recent studies from our laboratory and others have shown that increases in cytoplasmic superoxide (O(2)(·-)) levels and Akt activation play a key role in agonist-stimulated NF-κB activation and cardiomyocyte hypertrophy in vitro. In this study, we tested the hypothesis that adenovirus (Ad)-mediated intramyocardial gene transfer of cytoplasmic superoxide dismutase (AdCu/ZnSOD) or a dominant-negative form of Akt (AdDNAkt) in mice would attenuate pressure overload-induced increases in activation of the redox-sensitive transcription factor NF-κB and cardiac hypertrophy. Adult C57BL/6 mice were subjected to thoracic aortic banding (TAB) or sham surgery, and intramyocardial injections of viral vectors (AdCu/ZnSOD, AdDNAkt, or control) were performed.

Genetic silencing of Nox2 and Nox4 reveals differential roles of these NADPH oxidase homologues in the vasopressor and dipsogenic effects of brain angiotensin II.

The renin-angiotensin system exerts a tremendous influence over fluid balance and arterial pressure. Angiotensin II (Ang-II), the effector peptide of the renin-angiotensin system, acts in the central nervous system to regulate neurohumoral outflow and thirst. Dysregulation of Ang-II signaling in the central nervous system is implicated in cardiovascular diseases; however, the mechanisms remain poorly understood.

A differential role for endocytosis in receptor-mediated activation of Nox1.

Internalization of activated receptors to a compartment enriched with NAPDH oxidase and associated signaling molecules is expected to facilitate regulation of redox-mediated signal transduction. The aim of this study was to test the hypothesis that endocytosis is necessary for generation of reactive oxygen species (ROS) by Nox1 and for redox-dependent signaling in smooth muscle cells (SMCs). Within minutes of treatment with tumor necrosis factor (TNF)-alpha or thrombin, SMCs increased cellular levels of ROS that was inhibited by shRNA to Nox1.

Scavenging superoxide selectively in mouse forebrain is associated with improved cardiac function and survival following myocardial infarction.

Dysregulation in central nervous system (CNS) signaling that results in chronic sympathetic hyperactivity is now recognized to play a critical role in the pathogenesis of heart failure (HF) following myocardial infarction (MI). We recently demonstrated that adenovirus-mediated gene transfer of cytoplasmic superoxide dismutase (Ad-Cu/ZnSOD) to forebrain circumventricular organs, unique sensory structures that lack a blood-brain barrier and link peripheral blood-borne signals to central nervous system cardiovascular circuits, inhibits both the MI-induced activation of these central signaling pathways and the accompanying sympathoexcitation. Here, we tested the hypothesis that this forebrain-targeted reduction in oxidative stress translates into amelioration of the post-MI decline in myocardial function and increase in mortality.

Cardiovascular responses to peripheral chemoreflex activation and comparison of different methods to evaluate baroreflex gain in conscious mice using telemetry.

Peripheral chemoreceptors located in the carotid bodies are the primary sensors of systemic hypoxia. Although the pattern of responses elicited by peripheral chemoreceptor activation is well established in rats, lambs, and rabbits, the cardiovascular responses to peripheral chemoreflex activation in conscious mice have not been delineated. Here we report that stimulation of peripheral chemoreceptors by potassium cyanide (KCN) in conscious mice elicits a unique biphasic response in blood pressure that is characterized by an initial and robust rise followed by a decrease in blood pressure, which is accompanied by a marked reduction in heart rate.

Longitudinal noninvasive monitoring of transcription factor activation in cardiovascular regulatory nuclei using bioluminescence imaging.

The ability to monitor transcription factor (TF) activation in the central nervous system (CNS) has the potential to provide novel information regarding the molecular mechanisms underlying a wide range of neurobiological processes. However, traditional biochemical assays limit the mapping of TF activity to select time points. In vivo bioluminescence imaging (BLI) has emerged as an attractive technology for visualizing internal molecular events in the same animal over time.

Reactive oxygen species in the neuropathogenesis of hypertension.

New evidence that has emerged during the past several years clearly demonstrates that reactive oxygen species (ROS) in the brain play a crucial role in blood pressure regulation by serving as signaling molecules within neurons of cardiovascular control regions. In the forebrain, midbrain, and hindbrain, a key role for oxidant stress in the pathogenesis of angiotensin II-dependent and various other models of neurogenic hypertension has also been uncovered. As in the peripheral vasculature, NAD(P)H oxidase appears to be a major enzymatic source of brain ROS, and various homologues of the catalytic subunit of this enzyme appear to be differentially localized to cardiovascular-regulating nuclei in the brain.

Genetic ablation of angiotensinogen in the subfornical organ of the brain prevents the central angiotensinergic pressor response.

The subfornical organ (SFO) of the brain has long been considered a critical integrating center for the cardiovascular actions of the renin-angiotensin system (RAS). Early reports of angiotensin II (Ang II) immunoreactivity in the SFO and its neural projections to downstream cardiovascular nuclei raised the possibility that Ang II is produced locally and functions as a putative neurotransmitter in these circuits. However, evidence of functionally significant de novo synthesis of Ang II in the SFO has been lacking.

NADPH oxidases of the brain: distribution, regulation, and function.

The NADPH oxidase is a multi-subunit enzyme that catalyzes the reduction of molecular oxygen to form superoxide (O(2)(-)). While classically linked to the respiratory burst in neutrophils, recent evidence now shows that O(2)(-) (and associated reactive oxygen species, ROS) generated by NADPH oxidase in nonphagocytic cells serves myriad functions in health and disease. An entire new family of NADPH Oxidase (Nox) homologues has emerged, which vary widely in cell and tissue distribution, as well as in function and regulation.

Nox2-containing NADPH oxidase and Akt activation play a key role in angiotensin II-induced cardiomyocyte hypertrophy.

Angiotensin II (ANG II) has profound effects on the development and progression of pathological cardiac hypertrophy; however, the intracellular signaling mechanisms are not fully understood. In this study, we used genetic tools to test the hypothesis that increased formation of superoxide (O2-*) radicals from a Rac1-regulated Nox2-containing NADPH oxidase is a key upstream mediator of ANG II-induced activation of serine-threonine kinase Akt, and that this signaling cascade plays a crucial role in ANG II-dependent cardiomyocyte hypertrophy. ANG II caused a significant time-dependent increase in Rac1 activation and O2-* production in primary neonatal rat cardiomyocytes, and these responses were abolished by adenoviral (Ad)-mediated expression of a dominant-negative Rac1 (AdN17Rac1) or cytoplasmic Cu/ZnSOD (AdCu/ZnSOD).

Newborn lamb coronary artery reactivity is programmed by early gestation dexamethasone before the onset of systemic hypertension.

Exposure of the early gestation ovine fetus to exogenous glucocorticoids induces organ-specific alterations in postnatal cardiovascular physiology. To determine whether early gestation corticosteroid exposure alters coronary reactivity before the development of systemic hypertension, dexamethasone (0.28 mg x kg(-1) x day(-1)) was administered to pregnant ewes by intravenous infusion over 48 h beginning at 27 days gestation (term, 145 days).

Tempol therapy attenuates medial smooth muscle cell apoptosis and neointima formation after balloon catheter injury in carotid artery of diabetic rats.

Accumulating data support the hypothesis that reactive oxygen species (ROS) play a critical role in the vascular complications observed in diabetes. However, the mechanisms of ROS-mediated vascular complications in diabetes are not clear. We tested the hypothesis that ROS-mediated increase in proapoptotic factor Bax expression leads to medial smooth muscle cell (SMC) apoptosis that is associated with neointima formation.

Superoxide mediates angiotensin II-induced influx of extracellular calcium in neural cells.

We recently demonstrated that superoxide (O2*-) is a key signaling intermediate in central angiotensin II (Ang II)-elicited blood pressure and drinking responses, and that hypertension caused by systemic Ang II infusion involves oxidative stress in cardiovascular nuclei of the brain. Intracellular Ca2+ is known to play an important role in Ang II signaling in neurons, and it is also linked to reactive oxygen species mechanisms in neurons and other cell types. However, the potential cross-talk between Ang II, O2*-, and Ca2+ in neural cells remains unknown.

Inhibition of matrix metalloproteinase activity by TIMP-1 gene transfer effectively treats ischemic cardiomyopathy.

Background: Enhanced activity of matrix metalloproteinases (MMPs) has been associated with extracellular matrix degradation and ischemic heart failure in animal models and human patients. This study evaluated the effects of MMP inhibition by gene transfer of TIMP-1 in a rat model of ischemic cardiomyopathy.

Methods And Results: Rats underwent ligation of the left anterior descending coronary artery with direct intramyocardial injection of replication-deficient adenovirus encoding TIMP-1 (n=8) or null virus as control vector (n=8), and animals were analyzed after 6 weeks.

Requirement for Rac1-dependent NADPH oxidase in the cardiovascular and dipsogenic actions of angiotensin II in the brain.

We have shown that intracellular superoxide (O(2)(*-)) production in CNS neurons plays a key role in the pressor, bradycardic, and dipsogenic actions of Ang II in the brain. In this study, we tested the hypothesis that a Rac1-dependent NADPH oxidase is a key source of O(2)(*-) in Ang II-sensitive neurons and is involved in these central Ang II-dependent effects. We performed both in vitro and in vivo studies using adenoviral (Ad)-mediated expression of dominant-negative Rac1 (AdN17Rac1) to inhibit Ang II-stimulated Rac1 activation, an obligatory step in NADPH oxidase activation.

Hypertension caused by angiotensin II infusion involves increased superoxide production in the central nervous system.

Hypertension caused by angiotensin II (Ang II) infusion is associated with oxidative stress in the peripheral vasculature and kidney. The role of redox mechanisms in the central nervous system (CNS), a tissue known to be pivotal in Ang II-dependent hypertension, has not been investigated. We recently identified superoxide (O2*-) in the brain as a key signaling intermediate in the transient pressor response elicited by acute injection of Ang II directly into the CNS.

Superoxide is involved in the central nervous system activation and sympathoexcitation of myocardial infarction-induced heart failure.

Increased angiotensin II signaling in the brain has been shown to play a critical role in the excessive sympathoexcitation and development of heart failure (HF) after myocardial infarction (MI). We have recently demonstrated that reactive oxygen species mediate the actions of angiotensin II in the brain. In this study, we tested the hypothesis that increased redox signaling in central cardiovascular control regions is a key mechanism in the neurocardiovascular dysregulation that follows MI.

Adenovirus-mediated gene transfer to adult mouse cardiomyocytes is selectively influenced by culture medium.

Background: As development of cardiac gene therapies progresses, virally mediated genetic manipulations in cultured cardiomyocytes has become an important experimental approach. While adenovirus (Ad)-mediated gene transfer to neonatal and adult rat cardiomyocytes is well established, viral transduction of cultured adult mouse cardiomyocytes (AMCM) has been more difficult. This study was designed to test the hypothesis that culture medium is a critical determinant of efficient gene transfer in AMCM.

Modulation of baroreceptor activity by gene transfer of nitric oxide synthase to carotid sinus adventitia.

Administration of nitric oxide (NO) or NO donors to isolated carotid sinus and carotid bodies inhibits the activity of baroreceptor and chemoreceptor afferent nerves. Furthermore, NO synthase (NOS) is present in endothelial cells and in sensory nerves innervating the carotid sinus region. The major goal of this study was to determine whether overexpression of NOS in carotid sinus modulates baroreceptor activity.