Effect of pulmonary stretch receptor feedback and CO2 on upper airway and respiratory pump muscle activity in the rat
Article first published online: 5 AUG 2004
The Journal of Physiology
Volume 532, Issue 2, pages 525–534, April 2001
How to Cite
Bailey, E. F., Jones, C. L., Reeder, J. C., Fuller, D. D. and Fregosi, R. F. (2001), Effect of pulmonary stretch receptor feedback and CO2 on upper airway and respiratory pump muscle activity in the rat. The Journal of Physiology, 532: 525–534. doi: 10.1111/j.1469-7793.2001.0525f.x
Author's present address
D. D. Fuller: Department of Comparative Biosciences, Schoool of Veterinary Medicine, University of Wisconsin, Madison, WI 53705, USA.
- Issue published online: 5 AUG 2004
- Article first published online: 5 AUG 2004
- (Received 16 August 2000; accepted after revision 13 December 2000)
- 1Our purpose was to examine the effects of chemoreceptor stimulation and lung inflation on neural drive to tongue protrudor and retractor muscles in the rat.
- 2Inspiratory flow, tidal volume, transpulmonary pressure, compliance and electromyographic (EMG) activity of genioglossus (GG), hyoglossus (HG) and inspiratory intercostal (IIC) muscles were studied in 11 anaesthetized, tracheotomized and spontaneously breathing rats. Mean EMG activity during inspiration was compared with mean EMG activity during an occluded inspiration, at each of five levels of inspired CO2 (0, 3, 6, 9 and 12 %).
- 3Lung inflation suppressed EMG activity in all muscles, with the effect on both tongue muscles exceeding that of the intercostal muscles. Static elevations of end-expiratory lung volume evoked by 2 cmH2O positive end-expiratory pressure (PEEP) had no effect on tongue muscle activity.
- 4Despite increasing inspiratory flow, tidal volume and transpulmonary pressure, the inhibition of tongue muscle activity by lung inflation diminished as arterial PCO2(Pa,CO2) increased.
- 5The onset of tongue muscle activity relative to the onset of IIC muscle activity advanced with increases in Pa,CO2 but was unaffected by lung inflation. This suggests that hypoglossal and external intercostal motoneuron pools are controlled by different circuits or have different sensitivities to CO2, lung inflation and/or anaesthetic agents.
- 6We conclude that hypoglossal motoneuronal activity is more strongly influenced by chemoreceptor-mediated facilitation than by lung volume-mediated inhibition. Hypoglossal motoneurons driving tongue protrudor and retractor muscles respond identically to these stimuli.