Cephalically Situated Respiratory Mechanism in the Brain Stem of the Cat.

Abstract

The origin and course of the reticulospinal tracts in the cat, recently described by Papez 1 suggested the possibility of their being respiratory tracts. It was thought that this problem could best be approached by localizing the respiratory mechanism in this region of the brain stem. The material reported in this paper summarizes the results obtained thus far. The animals were given 1 gm. of urethane per kilo of body weight. Both carotids were tied at the time of cannulation of the trachea. Ether was used during surgical procedure. As the animal came from under ether, hyperpnea usually resulted spontaneously. 2 Hyperpnea was hastened by heating the preparation, or as in most cases, merely by stimulating the central sciatic stump with moderately strong induction shocks. This “rapid respiration mechanism” could be “shot” in the following ways: 1—exposing the corpora quadrigemina; 2—sectioning the brain stem through, or caudal to, the superior colliculi. However, the superior colliculi can be exposed without interfering at all with the mechanism. It was also found that a complete section of the brain stem cephalic to the corpora quadrigemina did not alter the respiratory rate. 3