Breathing frequency responses to pulmonary CO2 in an isolated lobe of the canine lung

J. O. Nilsestuen, R. L. Coon, F. O. Igler, E. J. Zuperku, J. P. Kampine

    Research output: Contribution to journalArticle

    7 Scopus citations


    Recent studies have indicated that the breathing frequency responses to inspired CO2 in part result from changes in pulmonary stretch receptor activity. Pulmonary CO2 may alter frequency by direct inhibition of stretch receptor discharge, or secondarily, by changes in airway mechanics. The vascularly isolated left lower lobe (LLL) of the canine lung was used to determine the effect of hypocapnic airway constriction on the pulmonary CO2 reflex. The upper and middle lobes of the left lung were removed and the right vagus nerve sectioned. Blood was recirculated through the LLL. Diaphragm electromyogram was used as an index of respiratory center activity and to trigger ventilation of the left lower lobe. Lobar hypocapnia increased peak airway pressure and reduced respiratory rate. However, infusion of isoproterenol or the use of a mechanical overflow system to block the airway pressure response prevented the frequency changes associated with CO2. Although both the direct and mechanical effects of CO2 on stretch receptors may contribute to the reflex, in the LLL preparation the mechanical effects predominate.

    Original languageEnglish (US)
    Pages (from-to)1201-1206
    Number of pages6
    JournalJournal of Applied Physiology Respiratory Environmental and Exercise Physiology
    Issue number6
    StatePublished - 1979

    ASJC Scopus subject areas

    • Physiology
    • Endocrinology

    Fingerprint Dive into the research topics of 'Breathing frequency responses to pulmonary CO<sub>2</sub> in an isolated lobe of the canine lung'. Together they form a unique fingerprint.

  • Cite this