In the heart the dominant action of [alpha]2-AR agonists is decrease in tachycardia (Through blocking cardioaccelerator
nerve) and bradycardia via [alpha]2A-AR (Through a vagomimetic action).
When the level of analgesia overlaps the level of the fourth thoracic vertebra, it blocks cardioaccelerator
fibers, causing pulse decrease and cardiac output reduction.
In this regard, the authors noted the need for comparable future studies in terms of normovolaemia at the time of the study, sympathetic block level (including or excluding cardioaccelerator
nerves), defining the developmental stage of sepsis (early or hyperdynamic, late or hypodynamic) and demonstration of a maintained sympathetic block (again the level including or excluding adrenal glands).
These and perhaps other stimuli are mediated by cardioaccelerator
fibers originating in the upper fetal thoracic spinal cord.