Tachypnoeic response to amyl nitrite inhalation in the rabbit

G. Macefield, B. S. Nail

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Abstract

Intratracheal inhalation of amyl nitrite, a non-specific smooth muscle relaxant, in the pentobarbitone/urethane anaesthetized rabbit caused reductions in tidal volume and both inspiratory and expiratory times, without a preceding apnoea, that were independent of the associated hypotension and of reflex influences from the carotid sinus region but dependent on supra-abdominal vagal integrity. In artificially ventilated, paralyzed rabbits amyl nitrite caused a pronounced sensitization of pulmonary stretch receptors (PSRs during the inflation phase, typically with a reduction in the level of activity during the deflation phase. The time course of the change in the pattern of PSR activity paralleled that of the tachypnoeic response. The sensitization of a small sample of rapidly adapting 'irritant' receptors was of a significantly shorter duration. A unitary analysis of non-myelinated vagal afferents was not attempted. The sensitization of these vagal afferents cannot be attributed to the smooth muscle relaxant properties of amyl nitrite since other relaxants (sodium nitrite, sodium nitroprusside, phentlamine) did not posses this capacity, and such properties would be expected to diminish their activities.

Original languageEnglish
Pages (from-to)169-179
Number of pages11
JournalRespiration Physiology
Volume62
Issue number2
DOIs
Publication statusPublished - Nov 1985
Externally publishedYes

Keywords

  • Amyl nitrite
  • Lung reflexes
  • Pulmonary stretch receptors
  • Rapid shallow breathing
  • Smooth muscle relaxant
  • Vagal afferents

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