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Ventral Medullary Inspiratory Neurons Recordings in Rats Submitted to Sino‐aortic Denervation
Author(s) -
Amorim Mateus R.,
Souza George Miguel P. R.,
Bonagamba Leni G. H.,
Machado Benedito H.
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.724.3
Subject(s) - baroreceptor , denervation , medicine , anesthesia , medulla , phrenic nerve , rostral ventrolateral medulla , respiratory system , cardiology , endocrinology , heart rate , blood pressure
There is experimental evidence showing that pre‐sympathetic neurons in the ventrolateral medulla have their firing frequency modulated by the respiratory network. After baroreceptors afferents removal [sino‐aortic denervation (SAD)], awake rats present normal levels of sympathetic activity and mean arterial pressure. However, the mechanisms involved in the respiratory modulation of the sympathetic activity after SAD remain unclear. In this study we hypothesized that rats present changes in the firing frequency of the inspiratory neurons after SAD. To test this hypothesis, male juvenile Wistar rats underwent to SAD or Sham surgery and on the 3rd day after the surgery they were surgically prepared for the in situ preparation. We recorded the activities of phrenic and thoracic sympathetic nerves as well as the single unit extracellular activities from the inspiratory neurons in the ventral medulla (CEUA #093/2013). The duration of inspiration significantly increased in SAD rats (P > 0.05). During inspiration, the firing frequency of Ramp‐I [Sham (n = 11) and SAD (n = 7, 52 ± 11 vs 56 ± 14 Hz)], Pre‐I / I [Sham (n = 13) and SAD (n = 11, 82 ± 15 vs 99 ± 20 Hz] and Late‐I neurons [Sham (n = 8) and SAD (n = 6, 8 ± 3 vs 9 ± 2 Hz] were not different between groups (P > 0.05). The data showed that the increase in time of inspiration observed in SAD rats was not associated with changes in the baseline firing frequency of the inspiratory neurons. However, these findings do not rule out the possibility that post‐inspiratory neurons are driving the activity of the pre‐sympathetic neurons after SAD. Further experiments are required to characterize the electrophysiological firing properties of the post‐inspiratory neurons in SAD rats. Support or Funding Information FAPESP, CAPES and CNPq