Hypoxic respiratory responses attenuated by ablation of the
cerebellum or fastigial nuclei.
Xu, Fadi, James Owen, and Donald T. Frazier.
Department of Physiology, University of Kentucky, Lexington,
Kentucky 40536
APStracts 2:0236A, 1995.
The general contribution of the cerebellum to hypoxic respiratory
responses and the special role of the fastigial nucleus (FN) in the
hypoxic respiratory reflex mediated via peripheral chemoreceptors
were investigated in anesthetized and spontaneously breathing cats.
Seven cats were exposed to isocapnic progressive hypoxia before and
after cerebellectomy by decreasing the fractional concentration of
end tidal O2 (FETo2) from 15+/-0.3% to 7% while maintaining the
pressure of end tidal CO2 (PETco2) at a constant level 30 mmHg. Five
additional cats inhaled 5 breaths of pure nitrogen (transient
hypoxia) and received sodium cyanide (CYN, 50 [mu]g, iv.) before and
after thermal lesions of the bilateral FN. The results showed that
cerebellectomy or FN lesions failed to alter the respiratory
variables (minute ventilation, I; tidal volume, VT; respiratory
frequency, f; and the peak of integrated diaphragm activity, _EMGdi)
during eupneic breathing. However, cerebellectomy, as compared to
control, did significantly attenuate I (FETo2
Received 20 March 1995; accepted in final form 23 May 1995.
APS Manuscript Number A301-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 June 1995.