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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Heightened respiratory-parasympathetic coupling to airways in the spontaneously hypertensive rat

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Moraes, Davi J. A. [1] ; da Silva, Melina P. [1] ; de Souza, Daniel P. [1] ; Felintro, Viviane [1] ; Paton, Julian F. R. [2]
Total Authors: 5
[1] Univ Sao Paulo, Sch Med Ribeirao Preto, Dept Physiol, BR-14049900 Ribeirao Preto, SP - Brazil
[2] Univ Auckland, Dept Physiol, Cardiovasc Auton Res Cluster, Fac Med & Hlth Sci, Auckland - New Zealand
Total Affiliations: 2
Document type: Journal article
Source: JOURNAL OF PHYSIOLOGY-LONDON; v. 599, n. 12, p. 3237-3252, JUN 2021.
Web of Science Citations: 0

Key points Carotid body (CB) chemoreceptors are hyperactive in hypertension, and their acute activation produces bronchoconstriction. We show that the respiratory-modulated bronchiolar tone, pulmonary parasympathetic efferent activity, and the firing frequency and synaptic excitation of bronchoconstrictor motoneurones in the nucleus ambiguus were all enhanced in spontaneous hypertensive (SH) rats. In SH rats, CB denervation reduced the respiratory-related parasympathetic-mediated bronchoconstrictor tone to levels seen in normotensive rats. Chemoreflex evoked bronchoconstrictor tone was heightened in SH versus normotensive rats. The intrinsic electrophysiological properties and morphology of bronchoconstrictor motoneurones were similar across rat strains. The heightened respiratory modulation of parasympathetic-mediated bronchoconstrictor tone to the airways in SH rats is caused by afferent drive from the CBs. Much research has described heightened sympathetic activity in hypertension and diminished parasympathetic tone, especially to the heart. The carotid body (CB) chemoreceptors exhibit hyperreflexia and are hyperactive, providing excitatory drive to sympathetic networks in hypertension. Given that acute CB activation produces reflex evoked bronchoconstriction via activation of parasympathetic vagal efferents, we hypothesised that the parasympathetic bronchoconstrictor activity is enhanced in spontaneously hypertensive (SH) rats and that this is dependent on CB inputs. In situ preparations of Wistar and SH rats were used in which bronchiolar tone, the pulmonary branch of the vagus (pVN) and phrenic nerves were recorded simultaneously; whole cell patch clamp recordings of bronchoconstrictor vagal motoneurones were also made from the nucleus ambiguus. Bronchiolar tone, pVN and bronchoconstrictor motoneurones were respiratory modulated and this modulation was enhanced in SH rats. These differences were all eliminated after CB denervation. Stimulation of the CBs increased the phrenic frequency that caused a summation of the respiratory-related increases in pVN, resulting in the development of bronchoconstrictor tone. This tone was exaggerated in SH rats. The enhanced respiratory-parasympathetic coupling to airways in SH rats was not due to differences in the intrinsic electrophysiological properties of bronchoconstrictor motoneurones but reflected heightened pre-inspiratory- and inspiratory-related synaptic drive. In summary, in SH rats the phasic respiratory modulation of parasympathetic tone to the airways is elevated and the greater development of this bronchoconstrictor tone is caused by the heightened afferent drive originating from the CBs. Thus, targeting the CBs may prove effective for increasing lower airway patency. (AU)

FAPESP's process: 19/11863-6 - Synaptic transmission and electrophysiological properties of bronchial motoneurons of the dorsal motor nucleus of the vagus from rats
Grantee:Davi José de Almeida Moraes
Support type: Regular Research Grants
FAPESP's process: 18/07027-5 - Role of astrocytes in the excitability of magnocelular neurons form supraoptic nucleus during changes in the plasma osmolality
Grantee:Melina Pires da Silva Moraes
Support type: Research Grants - Young Investigators Grants