Firing properties of ventral medullary respiratory neurons in sino-aortic denervated rats

Author(s)

Amorim, Mateus R. ^[1] ; Pena, Rodrigo F. O. ^[2] ; Souza, George M. P. R. ^[1] ; Bonagamba, Leni G. H. ^[1] ; Roque, Antonio C. ^[2] ; Machado, Benedito H. ^[1]

Affiliation

^[1] Univ Sao Paulo, Sch Med Ribeirao Preto, Dept Physiol, BR-14049900 Ribeirao Preto, SP - Brazil

^[2] Univ Sao Paulo, Sch Philosophy Sci & Letters Ribeirao Preto, Dept Phys, BR-14040900 Ribeirao Preto, SP - Brazil

• Document type: Journal article
• Source: Experimental Physiology; v. 104, n. 1, p. 39-49, JAN 2019.
• Web of Science Citations: 0

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. (AU)

• FAPESP's process: 13/06077-5 - Changes in the neural networks involved with the generation and control of sympathetic and respiratory activities in different experimental models of hypoxia
• Grantee: Benedito Honorio Machado
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 15/50122-0 - Dynamic phenomena in complex networks: basics and applications
• Grantee: Elbert Einstein Nehrer Macau
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 13/15195-1 - Electrophysiological characterization of respiratory and presympathetic neurons in the rostral ventrolateral medulla after sinoaortic denervation in rats
• Grantee: Mateus Ramos Amorim
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 13/07699-0 - Research, Innovation and Dissemination Center for Neuromathematics - NeuroMat
• Grantee: Oswaldo Baffa Filho
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 13/25667-8 - Mechanisms of propagation of epileptiform activity in a large-scale cortical model
• Grantee: Rodrigo Felipe de Oliveira Pena
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)