REFLEX RESPIRATORY EFFECTS FROM INTERMITTENT STIMULATION OF THE VAGUS AND SUPERIOR LARYNGEAL NERVES

Abstract

A stimulating circuit, controlled by changes in an animal''s intra-pleural pressure, is descr. Contact is made at the desired stage of inspiration, and broken at the corresponding stage of expiration. In dogs, anesthetized with barbital-Na and with both vagi sectioned, stimulation of the central stump of 1 vagus in the manner descr. causes reduction of the amplitude of inspiration. The rate of breathing is accelerated with the ordinary range of stimulus strength. Very strong shocks cause irregular slowing. The degree of acceleration varies with the stage at which the inspirations are inhibited. The greater the reduction of amplitude, the greater the increase in frequency. These observations seem to indicate that inhibitory fibers may indirectly govern the frequency, in the manner suggested by Head. Under these experimental conditions, stimulation of the vagus cuts short inspiration promptly and completely, while stimulation of the superior laryngeal does not. In the latter case, expiration does not occur until after one or more abortive efforts to complete the interrupted inspiration. In a, number of instances, however, respiration has been accelerated through the superior laryngeal nerve.