ANALYSIS OF CENTRAL CONTROL OF RESPIRATION BY THE USE OF CYANIDE

¹ Department of Pharmacology, University of Utah College of Medicine, Salt Lake City, Utah

The influence of effective doses of cyanide was determined on selected respiratory patterns produced by serial ablation and electrical stimulation of the brain stem in unanesthetized cats after peripheral chemoreceptor denervation. In the midcollicular decerebrate preparation, the respiratory response to cyanide is a mixture of depression and excitation. The depression is attributed to an effect upon supramedullary substrates because apneustic breathing of the midpontine animal is abolished by cyanide; the excitation is attributed to an effect upon medullary substrates because the gasping respiration of the medullary preparation is augmented by cyanide. Results of electrical stimulation of the medullary reticular formation suggest that cyanide stimulates two separate respiratory substrates, one concerned in the final integration of inspiration and the other concerned in the oscillating mechanism of breathing. It is concluded that respiratory rhythmicity originates in the medulla and that normal respiration results from a complex interact ion of the influences of neurounal substrates distributed throughout the lower brain stem.