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Long‐term facilitation differentially affects inspiratory network complexity in urethane‐anesthetized P12‐13 versus P14‐15 neonatal rats
Author(s) -
Reid Inefta M,
Yu Hui Jing,
Lin Robert,
Solomon Irene C
Publication year - 2007
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.21.5.a561-d
Subject(s) - respiratory system , approximate entropy , respiration , anesthesia , control of respiration , medicine , sample entropy , ventilation (architecture) , cardiology , psychology , anatomy , mechanical engineering , pattern recognition (psychology) , engineering , cognitive psychology
Long‐term facilitation (LTF) is a form of respiratory plasticity, which is expressed as a persistent increase in inspiratory motor output following intermittent, but not continuous, hypoxia. Although numerous studies have examined the timing and magnitude changes associated with respiratory LTF, little is known about LTF‐related changes in inspiratory network complexity. Therefore, we calculated the approximate entropy (ApEn; as an index of network complexity) of diaphragm EMG bursts recorded from 7 spontaneously breathing urethane‐anesthetized neonatal rats (P12‐15) before and at 5‐min intervals for at least 60‐min following three 5‐min episodes of hypoxia (8% O 2 ); all rats were continuously supplied with 2% or 4% CO 2 to minimize hypoxic respiratory depression. Under these conditions, respiratory LTF was observed primarily as an enhancement of burst frequency, which resulted from decreases in both T I and T E (except in P12 rats), and the peak frequency increase was noted at ≥35 min after the last hypoxic episode. ApEn was differentially affected as a function of age, such that in P12‐13 rats, ApEn values increased from 0.35±0.02 to 0.41±0.01 (P=0.013, n=4) at 50–60 min while in P14‐15 rats, ApEn values decreased from 0.40±0.01 to 0.34±0.01 (P=0.09, n=3) at 35–45 min. Our findings suggest that inspiratory network complexity is modified during LTF, and that the stage of development affects LTF‐related network reconfiguration. Supported by NS045321 and NS049310