Nonlinearities and Chaos-Like Control of Respiration During Square Wave Pulse Train Hypoxic Stimulation of the Carotid Body Chemoreceptors
The response of the ventilatory system of dogs to transient step and pulse train hypoxia at the carotid bodies is an abrupt increase in tidal volume during the first few seconds of stimulation Subsequent to the initial pulses of pulse trains, ventilation either slowly rises (2 s on - 2 s off pulses) or is sustained (3 s on - 3 s off pulses) at a new steady state intermediate between control and step perfusion ventilation. Data during the 2 s on - 2 s off pulse trains was not obtained for a sufficient length of time to determine the equilibrium level. Recovery from hypoxic perfusion is characterized by a slow return to control ventilation. A mathematical model of the carotid body control system based on these data was developed in the form of nonlinear differential equations. This model indicates that carotid body chemoreceptor mediation of the respiratory controller is a nonlinear system that contains linear dynamics with proportional and rate-sensitve elements in each of two parallel pathways.
KeywordsTidal Volume Pulse Train Carotid Body Ventilatory Response Arterial Oxygen Tension
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- 2.R. E. Dutton, E. J. Smith, P. K. Ghatak, and D. G. Davies, Dynamicsof the respiratory controller during carotid body hypoxia,J. Appl.Physiol. 35:844 (1973).Google Scholar
- 3.R. S. Fitzgerald, J. T. Zajtchuk, R. W. B. Penman, and J. F. Perkins Jr., Ventilation response to transient perfusion of carotid chemoreceptors, 207:1305 (1964).Google Scholar
- 4.R. E. Dutton, W. A. Hodson, D. G. Davies, and V. Chernick, Ventilatoryadaptation to a step change in PC02at the carotid bodies,J. Appl. Physiol. 23:195 (1967).Google Scholar
- 5.D. E. Woodram, J. T. Parer, R. P. Wennberg, and W. A. Hodson, Chemo-receptor response in initiation of breathing in the fetal lamb,J. Appl. Physiol. 35:120 (1972).Google Scholar
- 7.F. L. Eldridge, The importance of timing on the respiratory effects of intermittent carotid sinus nerve stimulation,J. Physiol. 222: 292 (1972).Google Scholar
- 8.F. L. Eldridge, The importance of timing on the respiratory effects of intermittent carotid body chemoreceptor stimulus,J. Physiol. 222:319 (1972).Google Scholar
- 9.P. A. Tsonis and A. A. Tsonis, Chaos: Principles and implications in biology,Perspect. Biol. Med. 5:27 (1989).Google Scholar