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Amorim MR, de Deus JL, Pereira CA, da Silva LEV, Borges GS, Ferreira NS, Batalhão ME, Antunes-Rodrigues J, Carnio EC, Tostes RC, Branco LGS. Baroreceptor denervation reduces inflammatory status but worsens cardiovascular collapse during systemic inflammation. Sci Rep 2020; 10:6990. [PMID: 32332859 PMCID: PMC7181760 DOI: 10.1038/s41598-020-63949-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 04/08/2020] [Indexed: 02/07/2023] Open
Abstract
Beyond the regulation of cardiovascular function, baroreceptor afferents play polymodal roles in health and disease. Sepsis is a life-threatening condition characterized by systemic inflammation (SI) and hemodynamic dysfunction. We hypothesized that baroreceptor denervation worsens lipopolysaccharide (LPS) induced-hemodynamic collapse and SI in conscious rats. We combined: (a) hemodynamic and thermoregulatory recordings after LPS administration at a septic-like non-lethal dose (b) analysis of the cardiovascular complexity, (c) evaluation of vascular function in mesenteric resistance vessels, and (d) measurements of inflammatory cytokines (plasma and spleen). LPS-induced drop in blood pressure was higher in sino-aortic denervated (SAD) rats. LPS-induced hemodynamic collapse was associated with SAD-dependent autonomic disbalance. LPS-induced vascular dysfunction was not affected by SAD. Surprisingly, SAD blunted LPS-induced surges of plasma and spleen cytokines. These data indicate that baroreceptor afferents are key to alleviate LPS-induced hemodynamic collapse, affecting the autonomic control of cardiovascular function, without affecting resistance blood vessels. Moreover, baroreflex modulation of the LPS-induced SI and hemodynamic collapse are not dependent of each other given that baroreceptor denervation worsened hypotension and reduced SI.
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Affiliation(s)
- Mateus R Amorim
- Dental School of Ribeirão Preto, 14040-904, University of São Paulo, São Paulo, Brazil.
| | - Júnia L de Deus
- Dental School of Ribeirão Preto, 14040-904, University of São Paulo, São Paulo, Brazil
| | - Camila A Pereira
- Ribeirão Preto Medical School, 14049-900, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Luiz E V da Silva
- Ribeirão Preto Medical School, 14049-900, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Gabriela S Borges
- Ribeirão Preto Medical School, 14049-900, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Nathanne S Ferreira
- Ribeirão Preto Medical School, 14049-900, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Marcelo E Batalhão
- Nursing School of Ribeirão Preto, 14040-902, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - José Antunes-Rodrigues
- Ribeirão Preto Medical School, 14049-900, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Evelin C Carnio
- Nursing School of Ribeirão Preto, 14040-902, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Rita C Tostes
- Ribeirão Preto Medical School, 14049-900, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Luiz G S Branco
- Dental School of Ribeirão Preto, 14040-904, University of São Paulo, São Paulo, Brazil. .,Ribeirão Preto Medical School, 14049-900, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
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Amorim MR, Pena RFO, Souza GMPR, Bonagamba LGH, Roque AC, Machado BH. Firing properties of ventral medullary respiratory neurons in sino-aortic denervated rats. Exp Physiol 2018; 104:39-49. [PMID: 30427561 DOI: 10.1113/ep087150] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 11/12/2018] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? After sino-aortic denervation (SAD), rats present normal levels of mean arterial pressure (MAP), high MAP variability and changes in breathing. However, mechanisms involved in SAD-induced respiratory changes and their impact on the modulation of sympathetic activity remain unclear. Herein, we characterized the firing frequency of medullary respiratory neurons after SAD. What is the main finding and its importance? Sino-aortic denervation-induced prolonged inspiration was associated with a reduced interburst frequency of pre-inspiratory/inspiratory neurons and an increased long-term variability of late inspiratory neurons, but no changes were observed in the ramp-inspiratory and post-inspiratory neurons. This imbalance in the respiratory network might contribute to the modulation of sympathetic activity after SAD. ABSTRACT In previous studies, we documented that after sino-aortic denervation (SAD) in rats there are significant changes in the breathing pattern, but no significant changes in sympathetic activity and mean arterial pressure compared with sham-operated rats. However, the neural mechanisms involved in the respiratory changes after SAD and the extent to which they might contribute to the observed normal sympathetic activity and mean arterial pressure remain unclear. Here, we hypothesized that after SAD, rats present with changes in the firing frequency of the ventral medullary inspiratory and post-inspiratory neurons. To test this hypothesis, male Wistar rats underwent SAD or sham surgery and 3 days later were surgically prepared for an in situ experiment. The duration of inspiration significantly increased in SAD rats. During inspiration, the total firing frequency of ramp-inspiratory, pre-inspiratory/inspiratory and late-inspiratory neurons was not different between groups. During post-inspiration, the total firing frequency of post-inspiratory neurons was also not different between groups. Furthermore, the data demonstrate a reduced interburst frequency of pre-inspiratory/inspiratory neurons and an increased long-term variability of late-inspiratory neurons in SAD compared with sham-operated rats. These findings indicate that the SAD-induced prolongation of inspiration was not accompanied by alterations in the total firing frequency of the ventral medullary respiratory neurons, but it was associated with changes in the long-term variability of late-inspiratory neurons. We suggest that the timing imbalance in the respiratory network in SAD rats might contribute to the modulation of presympathetic neurons after removal of baroreceptor afferents.
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Affiliation(s)
- Mateus R Amorim
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, 14049-900, Ribeirão Preto, SP, Brazil
| | - Rodrigo F O Pena
- Department of Physics, School of Philosophy, Sciences and Letters of Ribeirão Preto, University of São Paulo, 14040-900, Ribeirão Preto, SP, Brazil
| | - George M P R Souza
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, 14049-900, Ribeirão Preto, SP, Brazil
| | - Leni G H Bonagamba
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, 14049-900, Ribeirão Preto, SP, Brazil
| | - Antônio C Roque
- Department of Physics, School of Philosophy, Sciences and Letters of Ribeirão Preto, University of São Paulo, 14040-900, Ribeirão Preto, SP, Brazil
| | - Benedito H Machado
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, 14049-900, Ribeirão Preto, SP, Brazil
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