Over the past several decades, studies of the sympathetic nervous system in humans, sheep, rabbits, rats and mice have substantially increased mechanistic understanding of cardiovascular function and dysfunction. Recently, interest in sympathetic neural mechanisms contributing to blood pressure control has grown, due in part to the development of devices or surgical procedures, which treat hypertension by manipulating sympathetic outflow. Studies in animal models have provided important insights into physiological and pathophysiological mechanisms, which are not accessible in human studies. Across species and among laboratories, various approaches have been developed to record, quantify, analyze and interpret sympathetic nerve activity (SNA). In general, SNA demonstrates "bursting" behavior, where groups of action potentials are synchronized and linked to the cardiac cycle via the arterial baroreflex. In humans, it is common to quantify SNA as bursts/minute or bursts/100 heartbeats. This type of quantification can be done in other species, but is only commonly reported in sheep, which have heart rates similar to humans. In rabbits, rats and mice, SNA is often recorded relative to a maximal level elicited in the laboratory to control for differences in electrode position among animals or on different study days. SNA in humans can also be presented as total activity, where normalization to the largest burst is a common approach. The goal of the present paper is to put together a summary of "best practices" in several of the most common experimental models, and to discuss opportunities and challenges relative to the optimal measurement of SNA across species.
- Blood pressure
- autonomic nervous system
- nerve recording
- Copyright © 2016, American Journal of Physiology-Heart and Circulatory Physiology