This Program Project Grant (PPG) renewal describes a series of experiments designed to answer highly relevant questions concerning the mechanisms for sympatho-excitation in chronic heart failure (CHF). There has been a long history of interaction among the PI's in this PPG. We have contributed substantially to the literature in this area and are now proposing new studies that probe deeper into the origins of sympathetic regulation in CHF. Overall, the studies described here provide part of the molecular underpinning of the sympatho-excitatory process in CHF. The studies proposed are highly relevant to the mechanisms of CHF progression in humans. In Project I the focus will be on the role of an important antioxidant transcription factor, namely Nrf2 and its cytosolic teather, Keap1 in the regulation of neuronal oxidative stress in the rostral ventrolateral medulla. More importantly we will demonstrate that Nrf2 competes, within the nucleus, with NFkB for binding to the CREB binding protein thus reducing binding of Nrf2 to antioxidant response elements (AREs).
Specific aims of this project will also investigate the role of exercise training and ACE2 in the modulation of Nrf2 in the setting of CHF. Project II will focus on the role of the PVN in sympathetic regulation. The proposed studies target HIF1a and nitric oxide synthase as modulators of PVN neuronal activity in CHF in cells projecting to the RVLM. In addition, the hypothesis is tested that projections from afferent endings in the kidney modulate sympatho-excitation by activation of HIF1a. The modulation of this axis by exercise training will also be a component of this project. Project III concentrates on the sensitized carotid chemoreflex and carotid body in CHF. This project will determine how changes in blood flow translate into alterations in KLF2, a key transcription factor involved in chemoreceptor discharge sensitivity. The downstream pathways in the blood flow effects including NOS, Nrf2 and ACE/ACE2 will be examined. The role of HIF1a on the sympatho-respiratory changes to altered blood flow will be examined.
Aim 3 of this project will evaluate how chemoreflex-mediated changes in renal blood flow may alter venous capacitance and left ventricular function. Finally, each of the specific aims of Project III will evaluate the role of and the mechanism by which exercise training alters chemoreflex sensitivity in CHF. All studies will use state-of-the-art techniques ranging from the molecular and genetic to the integrative physiology of intact animals with and without CHF. (End of Abstract) PROJECT-001 - NRF2: NEURONAL OXIDATIVE STRESS AND SNA IN HEART FAILURE (Zucker, Irving H)
Chronic heart failure is a growing concern as the aging population of the United States increases. New strategies in the treatment of heart failure must be developed. This PPG is important and highly relevant to the heart failure epidemic in that it addresses a relatively neglected area of patho-physiology, namely sympathetic nerve activation. These studies will uncover new central and peripheral mechanisms and new potential targets for therapy in the heart failure state.
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