RESPIRATORY LOAD COMPENSATION .2. ROLE OF THE CEREBELLUM

Effects of inspiratory tracheal occlusion (TO) on respiratory duration (inspiratory and expiratory duration), ventilation, and the peak inte grated diaphragm electromyographic (integral EMGdi) response were test ed in 16 anesthetized cats before and after decerebellation with and w ithout vagal input. The same protocols were repeated in the decerebrat e preparation. Decerebellation did not significantly affect the baseli ne or the loaded values [tracheal occlusion (TO)] for respiratory dura tion, tidal volume, or magnitude of the integral EMGdi response. Vagal blockade eliminated the load-compensating responses in the intact and the decerebrate preparation. However, vagal blockade in concert with decerebellation resulted in a significant (P < 0.05) reversible inhibi tion of the peak integral EMGdi response during inspiratory TO. This s uggests that removal of vagal and cerebellar influences during loaded breathing unmasked inhibitory inputs to the respiratory pattern genera tor. With vagus intact, decerebellation before or after decerebration abolished the attenuation of the peak integral EMGdi response to TO ob served with decerebration alone. We conclude that the cerebellum does play a role in determining the pattern of the respiratory response to TO. This influence may be direct and/or indirect via interaction with information emanating from suprapontine, vagal, and nonvagal sources.