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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 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)
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)
The cardiac "sympathetic afferent" reflex (CSAR) has been reported to increase sympathetic outflow and depress baroreflex function via a central angiotensin II (ANG II) mechanism. In the present study, we examined the role of ANG II type 1 (AT(1)) receptors in the nucleus tractus solitarii (NTS) in mediating the interaction between the CSAR and the(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)
Activation of the cardiac "sympathetic afferent" reflex (CSAR) has been reported to depress the arterial baroreflex and enhance the arterial chemoreflex via a central mechanism. In the present study, we used single-unit extracellular recording techniques to examine the effects of stimulation of cardiac sympathetic afferents on baro- or chemosensitive(More)
Chronic heart failure (CHF) is characterized by increased sympathetic tone. The glutamatergic input in the rostral ventrolateral medulla (RVLM), which is a key region involved in sympathetic outflow, seems not to be involved in the generation of sympathetic tone in the normal state. The aim of this study was to determine the role of the RVLM glutamate(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)