Muscle sympathetic activity in resting and exercising humans with and without heart failure.
The sympathetic nervous system is critical for coordinating the cardiovascular response to various types of physical exercise. In a number of disease states, including human heart failure with reduced ejection fraction (HFrEF), this regulation can be disturbed and adversely affect outcome. The purpose of this review is to describe sympathetic activity at rest and during exercise in both healthy humans and those with HFrEF and outline factors, which influence these responses. We focus predominately on studies that report direct measurements of efferent sympathetic nerve traffic to skeletal muscle (muscle sympathetic nerve activity; MSNA) using intraneural microneurographic recordings. Differences in MSNA discharge between subjects with and without HFrEF both at rest and during exercise and the influence of exercise training on the sympathetic response to exercise will be discussed. In contrast to healthy controls, MSNA increases during mild to moderate dynamic exercise in the presence of HFrEF. This increase may contribute to the exercise intolerance characteristic of HFrEF by limiting muscle blood flow and may be attenuated by exercise training. Future investigations are needed to clarify the neural afferent mechanisms that contribute to efferent sympathetic activation at rest and during exercise in HFrEF.
a University Health Network and Mount Sinai Hospital Division of Cardiology, University of Toronto, Toronto, ON M5G 2C4, Canada.
Catherine F
CF
Notarius
b Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada.
Philip J
PJ
Millar
a University Health Network and Mount Sinai Hospital Division of Cardiology, University of Toronto, Toronto, ON M5G 2C4, Canada.
John S
JS
Floras
D000200:Action Potentials; D015444:Exercise; D017079:Exercise Tolerance; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000294:innervation*; D010101:Oxygen Consumption; D012018:Reflex; D012146:Rest; D013564:Sympathetic Nervous System / Q000503:physiopathology*
HFrEF; activité nerveuse sympathique dans le muscle; consommation d’oxygène de pointe; entraînement physique; exercice physique; exercise; exercise training; heart failure; insuffisance cardiaque; microneurographie; microneurography; muscle sympathetic nerve activity; peak oxygen uptake