THE EFFECTS OF DIRECT CHEMICAL AND ELECTRICAL STIMULATION OF THE RESPIRATORY CENTER IN THE CAT

Abstract

The effects of direct chemical and electrical stimulation of the brain stem were compared in a series of 115 cats using a modification of the Horsley Clarke stereotaxic instrument. Injs. of minute amts. (2 cu. mm.) of CO2-bicarbonate mixtures were followed often by immediate hyperpnea, particularly when these were injected into the region of the respiratory center previously outlined by Pitts, Magoun and Ranson. Acids (carbonic, lactic, hydrochloric), injected in the same manner, rarely stimulated respiration and often led to respiratory depression. The significance of these findings in relation to the current concepts of respiratory control is discussed. The response to the inj. of a number of other chemicals (NaHCO3, hypertonic and hypotonic NaCl solns., nicotine, strychnine and acetylcholine) was also tested.