Effect of FLCO2 Dynamics on Ti and Ttot in Spontaneously Breathing Birds

  • A. L. Kunz
  • R. D. TallmanJr.
Part of the Proceedings in Life Sciences book series (LIFE SCIENCES)

Summary

This study investigates whether the model of the respiratory pacemaker devised by Kunz and Miller (1974) is responsible for respiratory frequency in awake spontaneously breathing birds. This model hypothesizes that each inspiration causes an oscillation in fractional concentration of CO2 in the lung (\({\operatorname{F} _{{{\operatorname{LCO} }_2}}}\)) and that the timing of an event in this \({\operatorname{F} _{{{\operatorname{LCO} }_2}}}\) cycle sets the time of the next inspiration. These experiments used awake chickens which were spontaneously breathing from a gas flow line in which the fractional concentration of CO2 (\({\operatorname{F} _{{{\operatorname{ICO} }_2}}}\)) could be rapidly changed. During the first portion of the inspiratory period, \({\operatorname{F} _{{{\operatorname{ICO} }_2}}}\) was kept at a value near that of end expiratory \({\operatorname{F} _{{{\operatorname{CO} }_2}}}\) (0.05). Then τ seconds after the beginning of inspiration, the \({\operatorname{F} _{{{\operatorname{ICO} }_2}}}\) was decreased to 0.0 for 0.6 s and then returned to 0.05. Ventilatory movements were monitored by a whole body plethysmograph. When τ was varied within the range 0.1 to 0.6 s the inspiratory period, Ti, and total respiratory period, Ttot, were found to change proportionately. Sinusoidal and step forcing of τ showed an immediate response of Ti and Ttot with almost no hysteresis. These findings are believed to support the model.

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References

  1. Kunz, A.L., Miller, D.A.: Pacing respiratory movements with alveolar carbon dioxide oscillations. Federation Proc. 30, 270 (abstract) (1971)Google Scholar
  2. Kunz, A.L., Miller, D.A.: Pacing of avian respiration with CO2 oscillation. Respir. Physiol. 22, 167–177 (1974)PubMedCrossRefGoogle Scholar
  3. Kunz, A.L., Miller, D.A., Weissberg, R.M.: The avian respiratory pacemaker: An analysis of the effect of CO2 dynamics. In: Iberall, A.S., Guyton, A.C. (eds.). Regulation and Control in Physiological Systems. Int. Federation Automatic Control, Rochester, N.Y. (1973) p. 300–303Google Scholar
  4. Miller, D.A., Kunz, A.L.: Evidence that a cyclic rise in pulmonary CO2 triggers inspiration in birds. Respir. Physiol. 31, 193–202 (1977)PubMedCrossRefGoogle Scholar
  5. Tallman, R.D., Kunz, A.L.: The effect of changing the temporal pattern of \({\operatorname{F} _{{{\operatorname{CO} }_2}}}\) in the inspiratory gas flow of birds. Physiologist 19, 385 (abstract) (1976)Google Scholar
  6. Tallman, R.D., Jr., Kunz, A.L.: Changes in inspiratory duration as a function of when \({\operatorname{F} _{{{\operatorname{CO} }_2}}}\) is increased in the inspiratory gas flow of birds. Proc. Inter. Union of Physiol. Sciences 13, 742 (1977)Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1978

Authors and Affiliations

  • A. L. Kunz
    • 1
  • R. D. TallmanJr.
    • 1
  1. 1.Department of PhysiologyThe Ohio State UniversityColumbusUSA

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