LOCALIZATION OF THE CENTRAL RESPIRATORY MECHANISM AS STUDIED BY LOCAL COOLING OF THE SURFACE OF THE BRAIN STEM

Abstract

In dogs anaesthetized with morphine and urethane, slight or moderate local cooling of the posterior portion of the floor of the 4th ventricle depressed expiration leaving inspiration largely unaffected. Depending on the degree of this expiratory depression, respiratory rate could be increased, decreased or left unchanged. A lowering of the temp. from 37[degree] to 34[degree]C might be sufficient to definitely modify respiration. Marked cooling of this region may depress inspiration also, even causing apnea and death. Cooling more anterior portions of the brain stem produced effects qualitatively similar to the above, their magnitude varying inversely with the distance from the calamus.