Selective denervation of the aortic and carotid baroreceptors in rats

Abstract

New Findings What is the central question of this study?The traditional surgical approach for sino‐aortic denervation in rats leads to simultaneous carotid baroreceptor and chemoreceptor deactivation, which does not permit their individual study in different situations. What is the main finding and its importance?We have described a new surgical approach capable of selective denervation of the arterial (aortic and carotid) baroreceptors, keeping the carotid bodies (chemoreceptors) intact. It is understood that this technique might be a useful tool for investigating the relative role of the baro‐ and chemoreceptors in several physiological and pathophysiological conditions. Abstract Studies have demonstrated that the traditional surgical approach for sino‐aortic denervation in rats leads to simultaneous carotid baroreceptor and chemoreceptor deactivation. The present study reports a new surgical approach to denervate the aortic and the carotid baroreceptors selectively, keeping the carotid bodies (peripheral chemoreceptors) intact. Wistar rats were subjected to specific aortic and carotid baroreceptor denervation (BAROS‐X) or sham surgery (SHAM). Baroreflex activation was achieved by i.v. administration of phenylephrine, whereas peripheral chemoreflex activation was produced by i.v. administration of potassium cyanide. The SHAM and BAROS‐X rats displayed significant hypertensive responses to phenylephrine administration. However, the reflex bradycardia following the hypertensive response caused by phenylephrine was remarkable in SHAM, but not significant in the BAROS‐X animals, confirming the efficacy of the surgical procedure to abolish the baroreflex. In addition, the baroreflex activation elicited by phenylephrine increased carotid sinus nerve activity only in SHAM, but not in the BAROS‐X animals, providing support to the notion that the baroreceptor afferents were absent. Instead, the classical peripheral chemoreflex hypertensive and bradycardic responses to potassium cyanide were similar in both groups, suggesting that the carotid body chemoreceptors were preserved after BAROS‐X. In summary, we describe a new surgical approach in which only the baroreceptors are eliminated, while the carotid chemoreceptors are preserved. Therefore, it is understood that this procedure is potentially a useful tool for examining the relative roles of the arterial baroreceptors versus the chemoreceptors in several pathophysiological conditions, for instance, arterial hypertension and heart failure.

P2X3 receptor antagonism attenuates the progression of heart failure

“…Teflon-coated bipolar stainless steel electrodes were implanted in the Dia and the Abd muscles for EMG recordings 62 . Activation of the chemoreflex was evaluated by administration of KCN (0.05 mL, i.v., 0.05%) 58 . All recorded signals were amplified (10X; 1700 amplifier; A-M Systems, Sequim, WA, USA), band-pass filtered (0.3 Hz – 5 kHz), and acquired by a data acquisition system (5 kHz; ML866; ADInstruments) controlled by a computer running LabChart software (v.5.0; ADInstruments).…”

“…Baseline PN activity was assessed by burst frequency (Hz). To perform comparisons of the tSN recordings between groups, changes in activity were expressed as percentage changes in accordance with a scale (0–100%) determined for each preparation, as previously described 58 , 59 . Briefly, the maximal level of tSN produced by carotid body stimulation was used as 100%.…”

Physiological Sympathetic Activation Reduces Systemic Inflammation: Role of Baroreflex and Chemoreflex

“…The carotid baroreceptor denervation was performed according to the technique described by Castania et al. ( 29 ). Briefly, the common carotid region and the carotid bifurcation were exposed.…”

Autonomic Regulation of Inflammation in Conscious Animals

“…The arterial baroreflex is the main regulatory system responsible for the maintenance of arterial pressure within a relatively narrow range of oscillation [20][21][22]. Besides, it is well known that the chemoreceptors play a cardiovascular role under physiological conditions, for instance, concerning everyday occurrences, like natural sleep, and their importance in avoiding significant falls in blood pressure [23].…”