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. Author manuscript; available in PMC: 2012 Jan 1.
Published in final edited form as: Physiol Rev. 2011 Jan;91(1):1–77. doi: 10.1152/physrev.00060.2009

Fig. 10.

Fig. 10

Overall scheme of ET receptors in the baroreflex arc. Input from arterial baroreceptors enters the CNS via excitatory synapses with the nucleus tractus solitarius (NTS). NTS excitatory outputs project to the caudal ventrolateral medulla (CVLM), which sends inhibitory outputs to the rostral ventrolateral medulla (RVLM) from which emerge the preganglionic sympathetic neurons that synapse with the post-ganglionic sympathetic neurons within the paravertebral ganglia (G). The NTS and CVLM also send projections to the nucleus ambiguus (NA) and its vagal motor neurons from which emerge the parasympathetic outputs to the heart. Although not technically part of the baroreflex arc itself, the area postrema (AP) is a circumventricular organ outside the blood-brain barrier and receives input from substances within the plasma circulation. Inputs from the AP can modulate NTS neurons. The heart receives both postganglionic efferent sympathetic innervation (tachycardia) and parasympathetic innervation (bradycardia). ET influences the baroreflex arc via ETA or ETB receptors (see text for details). Within the central sites, most data support a role for ETA receptors.