RESPIRATORY EFFECTS FROM THE APPLICATION OF COCAINE, NICOTINE, AND LOBELINE TO THE FLOOR OF THE FOURTH VENTRICLE

Abstract

In anaesthetized dogs, the respiratory effects of application of cocaine to the obex were very similar to effects of cooling that region. If in sufficient conc., apnea and death may result, the apnea being frequently preceded by increasing inspiratory tonus. Apneustic respiration and the various stages leading to it observed in expts. on cooling, frequently result from cocaine, suggesting predominantly expiratory depression. Cocaine also depresses or abolishes the respiratory effects of inflation and deflation of the lungs, of central stimulation of the vagus and saphenous nerves and of CO2 administration. Nicotine causes an instantaneous apnea due apparently to expiratory stimulation. The apnea may be followed by a prolonged acceleration perhaps due to moderate expiratory depression. The effects of lobeline are similar to those of nicotine except that definite augmentation of respiration was never observed.