Hypoxia inhibits abdominal expiratory nerve activity

Ralph F Fregosi, S. L. Knuth, D. K. Ward, D. Bartlett

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

Our purpose was to examine the influence of steady-state changes in chemical stimuli, as well as discrete peripheral chemoreceptor stimulation, on abdominal expiratory motor activity. In decerebrate, paralyzed, vagotomized, and ventilated cats that had bilateral pneumothoraces, we recorded efferent activity from a phrenic nerve and from an abdominal nerve (cranial iliohypogastric nerve L1). All cats showed phasic expiratory abdominal nerve dischange at normocapnia [end-tidal PCO2 38 ± 2 Torr], but small doses (2-6 mg/kg) or pentobarbital sodium markedly depressed this activity. Hyperoxic hypercapnia consistently enhanced abdominal expiratory activity and shortened the burst duration. Isocapnic hypoxia caused inhibition of abdominal nerve discharge in 11 of 13 case. Carotid sinus nerve denervation (3 cats) exacerbated in hypoxic depression of abdominal nerve activity and depressed phrenic motor output. Stimulation of peripheral chemoreceptors with NaCN increased abdominal nerve discharge in 7 of 10 cats, although 2 cats exhibited marked inhibition. Four cats with intact neuraxis, but anesthetized with ketamine, yielded qualitatively similar results. We conclude that when cats are subjected to steady-state chemical stimuli in siolation (no interference from proprioceptive inputs), hypercapnia potentiates, but hypoxia attenuates abdominal expiratory nerve activity. Mechanisms to explain the selective inhibition of expiratory motor activity by hypoxia are proposed, and physiological implications are discussed.

Original languageEnglish (US)
Pages (from-to)211-220
Number of pages10
JournalJournal of Applied Physiology
Volume63
Issue number1
StatePublished - 1987
Externally publishedYes

Fingerprint

Cats
Hypercapnia
Motor Activity
Carotid Sinus
Phrenic Nerve
Cranial Nerves
Ketamine
Denervation
Pneumothorax
Pentobarbital
Diaphragm
Hypoxia
Inhibition (Psychology)

ASJC Scopus subject areas

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Fregosi, R. F., Knuth, S. L., Ward, D. K., & Bartlett, D. (1987). Hypoxia inhibits abdominal expiratory nerve activity. Journal of Applied Physiology, 63(1), 211-220.

Hypoxia inhibits abdominal expiratory nerve activity. / Fregosi, Ralph F; Knuth, S. L.; Ward, D. K.; Bartlett, D.

In: Journal of Applied Physiology, Vol. 63, No. 1, 1987, p. 211-220.

Research output: Contribution to journalArticle

Fregosi, RF, Knuth, SL, Ward, DK & Bartlett, D 1987, 'Hypoxia inhibits abdominal expiratory nerve activity', Journal of Applied Physiology, vol. 63, no. 1, pp. 211-220.
Fregosi, Ralph F ; Knuth, S. L. ; Ward, D. K. ; Bartlett, D. / Hypoxia inhibits abdominal expiratory nerve activity. In: Journal of Applied Physiology. 1987 ; Vol. 63, No. 1. pp. 211-220.
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