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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)
  • 22 Downloads

Abstract

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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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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