PROPRIOCEPTIVE RESPIRATORY REFLEXES OF THE VAGUS NERVE

Publisher Website
Google Scholar
Abstract
The respiratory functions of the vagus nerve were studied with special reference to the number of proprioceptive reflexes contributing towards the control of the rate of breathing. The procedure employed was to note the effects of selective block (progressive cold and pressure) and of non-selective interruption of vagal conduction (progressive section) on the changes of the rate of breathing reflexly elicited by inflation and deflation of the lungs. Progressive interruption, regardless of the methods employed, reduced the slowing from inflation and the acceleration from deflation and produced an approximately symmetrical convergence of the inflation, deflation and normal respiratory notes. This emphasizes the importance of the number of signals arriving at the central mechanism. Final convergence occurred at about 5[degree]C at about 25 min. of 1000 mm. Hg pressure and at about 3% uncut vagal fibers. After convergence and also after complete double vagotomy inflation of the lungs still accelerated the rate of breathing, thus demonstrating the extra vagal source of the resp. acceleration and of the reversal phenomenon described by Head, and Hammouda and Wilson. These reversal effects varied in degree with the magnitude of lung inflation and were roughly proportional to an accompanying fall in blood pressure. They appeared to arise in the carotid sinus region for they were eliminated by clamping of the carotids. It is suggested that an accessory mechanism, whereby breathing is accelerated by a continuous stimulation of a special group of pulmonary proprioceptive fibers, may not exist. The absence of differential effects during differential vagal block agrees with exclusive or predominant control of breathing by the inspiratory inhibitory fibers but does not positively eliminate the possibility of additional control by the expiratory inhibitory fibers.

This publication has 1 reference indexed in Scilit: