Methods of assessing vagus nerve activity and reflexes

Area of Science:

• Cardiovascular Physiology
• Autonomic Nervous System Research

Background:

• Cardiac parasympathetic activity modulates heart rate and influences cardiovascular health.
• Accurate assessment of cardiovagal tone is essential for understanding cardiac function and dysfunction.

Purpose of the Study:

• To review and critically evaluate methods for assessing cardiac parasympathetic (cardiovagal) activity in humans and animal models.
• To discuss the mechanisms, advantages, and limitations of various assessment techniques.

Main Methods:

• Heart rate (HR)-based methods: blockade of muscarinic cholinergic receptors, beat-to-beat HR variability (HRV), post-exercise HR recovery, and reflex-mediated HR changes.
• Direct recording of cardiovagal nerve activity in animal models.
• Use of decerebrate and in vitro preparations to minimize confounding factors like anesthesia.

Main Results:

• Different methods assess distinct cardiovagal mechanisms, providing complementary physiological and pathophysiological insights.
• Various afferent pathways (e.g., baroreceptors, chemoreceptors) modulate cardiovagal activity and heart rate.
• Non-cholinergic mechanisms and cardiovagal control of cardiac electrophysiology and contractility are also considered.

Conclusions:

• A comprehensive understanding of diverse assessment methods is vital for advancing cardiovascular research.
• Future research should explore novel techniques and refine existing ones for more accurate cardiovagal assessment.