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An exaggerated exercise pressor reflex (EPR) contributes to exercise intolerance and excessive sympatho-excitation in the chronic heart failure (CHF) state. However, the components of this reflex that are responsible for the exaggerated EPR in CHF remain unknown. To determine whether muscle afferent function is altered in CHF, we recorded the discharge of(More)
OBJECTIVES We investigated whether Angiotensin II (Ang II) modulates peripheral chemoreflex function through carotid body (CB) chemoreceptors in chronic heart failure (CHF). METHODS We measured renal sympathetic nerve activity (RSNA) in response to graded hypoxia before and after intravenous administration of Ang II (20 ng/kg/min, i.v. 30 min) or AT1(More)
We have previously reported that the expression of Angiotensin II (Ang II) type 1 receptors (AT1R) was increased in the rostral ventrolateral medulla (RVLM) of rabbits with chronic heart failure (CHF) and in the RVLM of normal rabbits infused with intracerebroventricular (ICV) Ang II. The present study investigated whether oxidant stress plays a role in Ang(More)
Upregulation of angiotensin II type 1 receptors (AT(1)R) in the rostral ventrolateral medulla (RVLM) contributes to the sympathoexcitation in the chronic heart failure (CHF). However, the role of angiotensin II type 2 receptor (AT(2)R) is not clear. In this study, we measured AT(1)R and AT(2)R protein expression in the RVLM and determined their effects on(More)
Elevated central angiotensin II (ANG II) plays a critical role in the sympathoexcitation of chronic heart failure (CHF) by stimulating upregulated ANG II type 1 receptors (AT(1)R) in the rostral ventrolateral medulla (RVLM). However, the link between enhanced ANG II signaling and alterations in the electrophysiological characteristics of neurons in the RVLM(More)
We recently reported that reactive oxygen species (ROS) plays an excitatory role in modulation of the exercise pressor reflex (EPR) in normal rats. In this study, we further tested two independent hypotheses: 1) ROS interacts with EPR-related ionotropic receptors such as the purinergic receptors (P(2)) and transient receptor potential vanilloid 1 receptors(More)
BACKGROUND In a recent study, we demonstrated that an increase in oxidative stress in the rostral ventrolateral medulla plays a critical role in the sympathoexcitation observed in chronic heart failure (CHF). Growing evidence indicates that exercise training evokes an antioxidative effect in CHF. In the present study, we therefore hypothesized that(More)
Chronic heart failure is often associated with sympathoexcitation and blunted arterial baroreflex function. These phenomena have been causally linked to elevated central ANG II mechanisms. Recent studies have shown that NAD(P)H oxidase-derived reactive oxygen species (ROS) are important mediators of ANG II signaling and therefore might play an essential(More)
BACKGROUND In a previous study, we showed that simvastatin (SIM) therapy normalized sympathetic outflow and cardiovascular reflex regulation in chronic heart failure (CHF). However, the precise neural and cellular pathways for these effects are unknown. We hypothesized that SIM exerts its beneficial effect on autonomic function in CHF by downregulating(More)
OBJECTIVE A previous study from this laboratory showed that elevation of endogenous angiotensin II (Ang II) and upregulation of the angiotensin II type 1 (AT(1)) receptor in the carotid body (CB) are involved in the enhanced peripheral chemoreceptor sensitivity in rabbits with chronic heart failure (CHF). NADPH oxidase-derived superoxide anion mediates the(More)