Baroreceptors in the Aortic Arch and Their Potential Role in Aortic Dissection and Aneurysms

Abstract

The arterial baroreflex is a key autonomic regulator of blood pressure whose dysfunction has been related to several cardiovascular diseases. Changes in blood pressure are sensed by specific mechanosensory proteins, called baroreceptors, particularly located in the outer layer of the carotid sinus and the inner curvature of the aortic arch. The signal is propagated along the afferent nerves to the central nervous system and serves as negative feedback of the heart rate. Despite extensive research, the precise molecular nature of baroreceptors remains elusive. Current knowledge assumes that baroreceptors are ion channels at the nerve endings within the outer layer of the arteries. However, the evidence is based mainly on animal experiments, and the specific types of mechanosensitive receptors responsible for the signal transduction are still unknown. Only a few studies have investigated mechanosensory transmission in the aortic arch. In addition, although aortic dissection, and particularly type A involving the aortic arch, is one of the most life-threatening cardiovascular disorders, there is no knowledge about the impact of aortic dissection on baroreceptor function. In this review, we aim not to highlight the regulation of the heart rate but what mechanical stimuli and what possible ion channels transfer the corresponding signal within the aortic arch, summarizing and updating the current knowledge about baroreceptors, specifically in the aortic arch, and the impact of aortic pathologies on their function.

Analysis of Mechanisms for Increased Blood Pressure Variability in Rats Continuously Infused with Angiotensin II

“…We examined rat aortic sections to see whether the above-mentioned alterations of BRS were related to any morphological change in the aortic arch, where baroreceptors are located [11]. Figures 5(a)–5(c) are representative photos of hematoxylin-eosin-stained sections of the aortic arch at 12.5x magnification.…”

“…The aim of this study was to explore the mechanisms behind augmentation of BPV in hypertension induced by continuous infusion of Ang II. Accordingly, we examined the relationship between BP and heart rate (HR), alterations in baroreceptor reflex sensitivity (BRS), and medial area of the aortic arch where baroreceptors are located [11], following continuous infusion of Ang II over 14 days. In addition, we treated Ang II-infused rats with azelnidipine to clarify the mechanism of action of Ang II and to examine the effects of calcium channel blocker.…”

eNOS plays essential roles in the developing heart and aorta linked to disruption of Notch signalling

“…eNOS null mice are hypertensive, and high-pressure baroreceptors that sense blood pressure and feed back to modulate vasal tone are localised within the adventitia of the aortic arch in both the fetus and the adult. These baroreceptors are stretch receptors that sense distension of the arterial wall in response to increased blood pressure (reviewed by Reutersberg et al, 2022 ). Studies in which eNOS was reconstituted in the endothelium of adult eNOS null mice showed that although this restored vascular reactivity, the mice continued to be hypertensive ( Suvorava et al, 2015 ).…”

A Rare Case of Profound Sinus Bradycardia in a Patient With Descending Aortic Dissection

“…An aortic dissection can potentially cause disruption in the signal transduction of blood pressure homeostasis [12]. The stress that the aortic wall experiences during an acute dissection can stimulate the mechano-sensory baroreceptors in the outer layer of the aortic arch, which in turn, via stretch of the carotid sinus, initiates the baroreceptor response that leads to bradycardia.…”