Pflügers Archiv

, Volume 399, Issue 2, pp 119–122 | Cite as

Effects of brainstem lesions on the nasopharyngeal reflex in the conscious rabbit

  • J. P. Chalmers
  • M. J. West
Excitable Tissues and Central Nervous Physiology (C)


The cardiovascular responses evoked through the nasopharyngeal reflex by the inhalation of formaldehyde vapour were studied in conscious rabbits after bilateral electrolytic lesions of the ventrolateral medulla coinciding with the A1 group of catecholamine cells. Arterial blood pressure was measured in the central ear artery, heart rate was determined from the arterial pressure trace, and iliac blood flow was determined using a Doppler ultrasonic flow meter placed around the lower abdominal aorta. There were no significant changes in the heart rate, blood pressure and iliac conductance responses elicited through the nasopharyngeal reflexes of sham operated animals in which electrodes were inserted without the passage of current.

The blood pressure changes produced by inhalation of formaldehyde in control rabbits were not significantly altered in animals with ventrolateral medullary lesions. However, the magnitude of the bradycardia and of the fall in iliac conductance evoked by the inhalation of formaldehyde were approximately halved 4 h and 1 day after the lesions but were fully restored at 2 weeks. These experiments suggest that the A1 group of catecholamine neurones help mediate the bradycardia and vasoconstriction elicited through nasopharyngeal reflexes in terrestial animals exposed to noxious vapours.

Key words

Cardiovascular control Blood pressure Heart rate Vascular resistance Central noradrenaline nerves A1 catecholamine neurones Ventrolateral medulla oblongata 


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  1. Blessing WW, Chalmers JP, Howe PRC (1979) Distribution of catecholamine-containing cell bodies in the rabbit central nervous system. J Comp Neurol 179:407–424Google Scholar
  2. Blessing WW, West MJ, Chalmers JP (1981) Hypertension, bradycardia and pulmonary oedema in the conscious rabbit after brainstem lesions coinciding with the A1 group of catecholamine neurons. Circ Res 49:949–958Google Scholar
  3. Chalmers JP, White SW, Geffen LB, Rush R (1977) The role of central catecholamines in the control of blood pressure through the baroreceptor reflex and the nasopharyngeal reflex in the rabbit. Hypertension and Brain Mechanisms. Prog Brain Res 47:85–93Google Scholar
  4. Dahlstrom A, Fuxe K (1964) Evidence for the existence of monoamine-containing neurons in the central nervous system. I. Demonstration of monoamines in the cell bodies of brain stem neurons. Acta Physiol Scand 62:1–55Google Scholar
  5. Fletcher PJ, Korner PI, Angus JA, Oliver JR (1976) Changes in cardiac output and total peripheral resistance during development of renal hypertension. Circ Res 39:633–639Google Scholar
  6. Korner PI (1979) Central nervous control of autonomic cardiovascular function. In: Berne RM (ed) Handbook of physiology, the cardiovascular system I, chapter 20. American Physiological Society, Bethesda, MD, pp 691–739Google Scholar
  7. Korner PI, Oliver JR, Reynoldson JA, Head GA, Carson VJ, Walker MMcD (1978) Cardiovascular and behavioural effects of intracisternal 6-hydroxydopamine in the rabbit. Eur J Pharmacol 53:83–93Google Scholar
  8. Palkovits M, Jacobowitz DM (1974) Topographic atlas of catecholamines and acetylcholinesterase-containing neurons in the rat brain. II. Hindbrain (mesencephalon, rhombencephalon). J Comp Neurol 157:29–42Google Scholar
  9. Snedecor GW, Cochran WG (1967) Statistical methods, ed. 6. State University Press, Ames, Iowa, pp 91–119 and 299–338Google Scholar
  10. Talman WT, Snyder DS, Reis DJ (1980) Chronic lability of arterial pressure produced by destruction of A2 catecholaminergic neurons in rat brainstem. Circ Res 46:842–853Google Scholar
  11. Wallenstein S, Zuckei CL, Fleiss JL (1980) Some statistical methods useful in circulation research. Circ Res 47:1–9Google Scholar
  12. West MJ, Angus JA, Korner PI (1975) Estimation of non-autonomic and autonomic components of iliac bed vascular resistance in renal hypertensive rabbits. Cardiovasc Res 9:697–706Google Scholar
  13. West MJ, Blessing WW, Chalmers JP (1981) Arterial baroreceptor reflex function in the conscious rabbit after brainstem lesions coinciding with the A1 group of catecholamine neurons. Circ Res 49:959–970Google Scholar
  14. White S, McRitchie RJ, Korner PI (1975) Central nervous system control of cardiorespiratory nasopharyngeal reflexes in the rabbit. Am J Physiol 228:404–409Google Scholar

Copyright information

© Springer-Verlag 1983

Authors and Affiliations

  • J. P. Chalmers
    • 1
  • M. J. West
    • 1
  1. 1.Department of Medicine and Centre for NeuroscienceThe Flinders University of South Australia, Flinders Medical CentreAdelaide

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