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Respiratory Network Complexity In The Transverse Medullary Slice Preparation From Neonatal Rat
Author(s) -
Foglyano Ryan M,
Chen Xinnian,
Shafer Geoffrey O,
Wilson Christopher G,
Solomon Irene C
Publication year - 2006
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.20.4.a781-b
Subject(s) - approximate entropy , respiratory system , anesthesia , slice preparation , medicine , medullary cavity , chemistry , electrophysiology , entropy (arrow of time) , physics , quantum mechanics
The in vitro medullary slice preparation from neonatal rodents is capable of generating spontaneous respiratory rhythm as long as it contains the pre‐Bötzinger complex. In this reduced preparation, inspiratory motor output is generally recorded from the hypoglossal (XII) nerve while the preparation is superfused with an artificial cerebrospinal fluid (aCSF) containing an elevated concentration of KCl (~8–9 mM) to enhance excitability and inspiratory drive. The complexity of this reduced respiratory network, including the influence of elevated KCl, is unknown. We hypothesized that the increased excitability induced by higher concentrations of KCl results in an increase in the synchrony (or order) of the inspiratory network. To address this possibility, we calculated the approximate entropy (ApEn; as an index of network complexity) of XII bursts recorded from slice preparations obtained from neonatal rat (P1‐P5) during application of 3, 5, 7, 8, and 9 mM KCl in the aCSF; 3–4 concentrations of KCl were used in each experiment. The ApEn was similar at 3, 5, and 7 mM KCl with values (mean±SE) of 0.435±0.011 (n=18), 0.439±0.013 (n=15), 0.437±0.018 (n=15), respectively, and slightly lower at 8 and 9 mM KCl with ApEn values of 0.415±0.014 (n=12) and 0.391±0.008 (n=7), respectively. Overall, these ApEn values are substantially lower than those seen in more intact in vitro ( e.g. , arterially‐perfused rat) and in vivo ( e.g. , anesthetized/decerebrate rat, piglet, cat) preparations. Although we were unable to detect a statistically significant difference (p=0.067), these observations suggest that the reduced central respiratory network exhibits less complexity when excitability is enhanced by higher concentrations of KCl. Supported by NS045321