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. 1994 Mar 15;475(3):519–529. doi: 10.1113/jphysiol.1994.sp020090

Reflex recruitment of medullary gasping mechanisms in eupnoea by pharyngeal stimulation in cats.

M L Fung 1, W M St John 1, Z Tomori 1
PMCID: PMC1160402  PMID: 8006833

Abstract

1. Mechanical stimulation of the naso- and oropharynx causes the replacement of the eupnoeic ventilatory pattern by a brief, but large, burst of activity of the phrenic nerve. Our purpose was to define whether these changes in phrenic activity represent a switch to gasping. 2. In decerebrate, vagotomized, paralysed and ventilated cats, mechanical stimulation of the pharynx was performed during eupnoea, apneusis and gasping. The latter two ventilatory patterns were produced by ventilating the experimental animal with 1.0% carbon monoxide in air or with 100% nitrogen. Eupnoea could be re-established by a recommencement of ventilation with oxygen. 3. The rate of rise of phrenic activity and its peak height were much greater following mechanical stimulation of the pharynx than the phrenic bursts of eupnoea or apneusis. The durations of phrenic burst and the period between these were much less following pharyngeal stimulation. In contrast, these variables of phrenic activity were the same during pharyngeal stimulation and in gasping. 4. Previous studies had established that activity within a region of the lateral tegmental field of medulla is critical for the manifestation of gasping. Hence, electrical stimulation of this region during gasping elicits premature gasps whereas its ablation irreversibly eliminates gasping. 5. We positioned a multibarrelled pipette in the critical medullary region for gasping. Its location was verified, once gasping was established in hypoxia or anoxia, by the elicitation of premature gasps following electrical stimulation. Neurons in this region were destroyed by microinjections of the neurotoxin kainic acid; in a few experiments the region was destroyed by electrolytic lesions. 6. Following destruction of the region of the lateral tegmental field, gasping could no longer be provoked in anoxia. In contrast, the eupnoeic pattern of phrenic activity continued. However, mechanical stimulation of the pharynx no longer caused any changes in the on-going pattern of phrenic activity. 7. We conclude that mechanical stimulation of the pharynx elicits a powerful reflex by which eupnoea is suppressed and gasping is elicited. Stated differently, the changes in phrenic activity during this pharyngeal stimulation in fact represent gasps. 8. Gasps are dependent upon activity within a region of the lateral tegmental field of the medulla. This region plays no role in the neurogenesis of eupnoea. Hence, our results provide additional support for the concept that there are multiple sites for ventilatory neurogenesis in the mammalian brainstem.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Batsel H. L., Lines A. J., Jr Bulbar respiratory neurons participating in the sniff reflex in the cat. Exp Neurol. 1973 Jun;39(3):469–481. doi: 10.1016/0014-4886(73)90031-9. [DOI] [PubMed] [Google Scholar]
  2. Berger A. J., Mitchell R. A. Lateralized phrenic nerve responses to stimulating respiratory afferents in the cat. Am J Physiol. 1976 May;230(5):1314–1320. doi: 10.1152/ajplegacy.1976.230.5.1314. [DOI] [PubMed] [Google Scholar]
  3. Boushey H. A., Richardson P. S., Widdicombe J. G., Wise J. C. The response of laryngeal afferent fibres to mechanical and chemical stimuli. J Physiol. 1974 Jul;240(1):153–175. doi: 10.1113/jphysiol.1974.sp010605. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. COTTLE M. K. DEGENERATION STUDIES OF PRIMARY AFFERENTS OF IXTH AND XTH CRANIAL NERVES IN THE CAT. J Comp Neurol. 1964 Jun;122:329–345. doi: 10.1002/cne.901220304. [DOI] [PubMed] [Google Scholar]
  5. Jakus J., Tomori Z., Bosel'ová L., Nagyová B., Kubinec V. Respiration and airway reflexes after transversal brain stem lesions in cats. Physiol Bohemoslov. 1987;36(4):329–340. [PubMed] [Google Scholar]
  6. Jodkowski J. S., Guthrie R. D., Cameron W. E. The activity pattern of phrenic motoneurons during the aspiration reflex: an intracellular study. Brain Res. 1989 Dec 29;505(2):187–194. doi: 10.1016/0006-8993(89)91441-8. [DOI] [PubMed] [Google Scholar]
  7. Nail B. S., Sterling G. M., Widdicombe J. G. Patterns of spontaneous and reflexly-induced activity in phrenic and intercostal motoneurons. Exp Brain Res. 1972;15(3):318–332. doi: 10.1007/BF00235915. [DOI] [PubMed] [Google Scholar]
  8. Neubauer J. A., Melton J. E., Edelman N. H. Modulation of respiration during brain hypoxia. J Appl Physiol (1985) 1990 Feb;68(2):441–451. doi: 10.1152/jappl.1990.68.2.441. [DOI] [PubMed] [Google Scholar]
  9. Richardson C. A. Unique spectral peak in phrenic nerve activity characterizes gasps in decerebrate cats. J Appl Physiol (1985) 1986 Mar;60(3):782–790. doi: 10.1152/jappl.1986.60.3.782. [DOI] [PubMed] [Google Scholar]
  10. St John W. M., Bartlett D., Jr Comparison of phrenic motoneuron activity during eupnea and gasping. J Appl Physiol Respir Environ Exerc Physiol. 1981 May;50(5):994–998. doi: 10.1152/jappl.1981.50.5.994. [DOI] [PubMed] [Google Scholar]
  11. St John W. M., Bledsoe T. A., Sokol H. W. Identification of medullary loci critical for neurogenesis of gasping. J Appl Physiol Respir Environ Exerc Physiol. 1984 Apr;56(4):1008–1019. doi: 10.1152/jappl.1984.56.4.1008. [DOI] [PubMed] [Google Scholar]
  12. St John W. M., Bledsoe T. A., Tenney S. M. Characterization by stimulation of medullary mechanisms underlying gasping neurogenesis. J Appl Physiol (1985) 1985 Jan;58(1):121–128. doi: 10.1152/jappl.1985.58.1.121. [DOI] [PubMed] [Google Scholar]
  13. St John W. M. Differential alteration by hypercapnia and hypoxia of the apneustic respiratory pattern in decerebrate cats. J Physiol. 1979 Feb;287:467–491. doi: 10.1113/jphysiol.1979.sp012671. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. St John W. M., Knuth K. V. A characterization of the respiratory pattern of gasping. J Appl Physiol Respir Environ Exerc Physiol. 1981 May;50(5):984–993. doi: 10.1152/jappl.1981.50.5.984. [DOI] [PubMed] [Google Scholar]
  15. St John W. M. Neurogenesis, control, and functional significance of gasping. J Appl Physiol (1985) 1990 Apr;68(4):1305–1315. doi: 10.1152/jappl.1990.68.4.1305. [DOI] [PubMed] [Google Scholar]
  16. St John W. M., Zhou D., Fregosi R. F. Expiratory neural activities in gasping. J Appl Physiol (1985) 1989 Jan;66(1):223–231. doi: 10.1152/jappl.1989.66.1.223. [DOI] [PubMed] [Google Scholar]
  17. Sun M. K., Jeske I. T., Reis D. J. Cyanide excites medullary sympathoexcitatory neurons in rats. Am J Physiol. 1992 Feb;262(2 Pt 2):R182–R189. doi: 10.1152/ajpregu.1992.262.2.R182. [DOI] [PubMed] [Google Scholar]
  18. Tomori Z., Benacka R., Donic V., Tkácová R. Reversal of apnoea by aspiration reflex in anaesthetized cats. Eur Respir J. 1991 Oct;4(9):1117–1125. [PubMed] [Google Scholar]
  19. Tomori Z., Donic V., Kurpas M. Comparison of inspiratory effort in sniff-like aspiration reflex, gasping and normal breathing in cats. Eur Respir J. 1993 Jan;6(1):53–59. [PubMed] [Google Scholar]
  20. Tomori Z., Widdicombe J. G. Muscular, bronchomotor and cardiovascular reflexes elicited by mechanical stimulation of the respiratory tract. J Physiol. 1969 Jan;200(1):25–49. doi: 10.1113/jphysiol.1969.sp008680. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Zhou D., Wasicko M. J., Hu J. M., St John W. M. Differing activities of medullary respiratory neurons in eupnea and gasping. J Appl Physiol (1985) 1991 Mar;70(3):1265–1270. doi: 10.1152/jappl.1991.70.3.1265. [DOI] [PubMed] [Google Scholar]

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