Respiratory-related neurons of the fastigial nucleus in response to
chemical and mechanical challenges.
Xu, Fadi, and Donald T. Frazier.
Department of Physiology, University of Kentucky, Lexington,
Kentucky 40536
APStracts 3:0547A, 1996.
Responses of cerebellar respiratory-related neurons (CRRNs) within the
rostral fastigial nucleus (FNr) and the phrenic neurogram (PN) to
activation of respiratory mechano- and chemo-receptors were recorded
in anesthetized, paralyzed and ventilated cats. Respiratory
challenges included: a) cessation of the ventilator for single breath
at end of inspiration (LI) or at functional residual capacity (FRC);
b) cessation of the ventilator for multiple breaths (MB); and c)
exposure to hypercapnia. Nineteen CRRNs having spontaneously activity
during control were characterized as either independent (basic, n=14)
or dependent (pump, n=5) upon the ventilator movement. Thirteen
recruited CRRNs showed no respiratory-related activity until
breathing was stressed. Burst durations of expiratory CRRNs were
prolonged by sustained LI but inhibited when the volume was sustained
at FRC, vice versa for inspiratory CRRNs. MB cessation of the
ventilator and hypercapnia significantly increased the firing rate
and/or burst duration concomitant with changes noted in the PN. We
conclude that CRRNs respond to respiratory inputs from CO2 chemo- and
pulmonary mechano-receptors in the absence of skeletal muscle
contraction.
Received 2 May 1996; accepted in final form 18 November 1996.
APS Manuscript Number A421-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996