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Influence of hypercapnia and hypoxia on abdominal expiratory nerve activity in the rat
Author(s) -
Fregosi Ralph,
Iizuka Makito
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.21.6.a921-b
Subject(s) - hypercapnia , chemoreceptor , hypoxia (environmental) , anesthesia , phrenic nerve , medicine , stimulation , respiratory system , chemistry , oxygen , acidosis , organic chemistry , receptor
We studied the influence of hyperoxic hypercapnia and isocapnic hypoxia on the neural drive to abdominal muscles in anesthetized and decerebrate vagotomized, paralyzed and mechanically ventilated rats, with special emphasis on the temporal response to sustained (4 min) chemoreceptor stimulation. Electrical activity was recorded from phrenic and abdominal muscle nerves. Two min of hypercapnia or hypoxia of progressively increasing severity evoked steadily increasing, low amplitude expiratory discharge that persisted throughout the expiratory phase (E‐all activity), but was inhibited during inspiration. We also observed late expiratory, high‐amplitude bursts (E2 activity) superimposed on this steady activity, but usually only at the highest levels of respiratory drive. In sustained, severe hypoxia, E2 abdominal activity increased over the first 1–2 min, but was then reduced or abolished as hypoxia was maintained. In contrast, phrenic activity was sustained. The increase in both phrenic and abdominal activity in severe hypercapnia was sustained for the entire 4‐min observation period. These data demonstrate that chemoreceptor stimulation increases expiratory motor drive to abdominal muscles in the rat, and support previous work in the cat, demonstrating that systemic hypoxia differentially effects motor output to inspiratory and expiratory muscles. Support by NHLBI and the AHA.