Effect of stimulation of muscle afferents on ventilation of dogs.

Abstract

Respiratory effects of stimulation of the central end of the lateral gastrocnemius-soleus nerve at multiples of threshold (motor twitch) were determined in dogs anesthetized with Na pentobarbital. The nature of the fiber stimulated was deduced from the strength of the stimulus used. Stimulation at threshold and up to 5 times threshold produced 3.6-13.1% augmentation of ventilation. These impulses probably originate in group I and group II fibers of muscle spindles and tendon organs. Stimulation of the nerve at 10, 20, and 40 times threshold produces increase in ventilation due to the stimulation of group HI afferents which are known to be connected to pressure receptors, and the excitatory effect persists for a while after the stimulus is over. Natural stimulation of these endings by pressure of the order of 1 kg/cm2 to 5 kg/cm2 also produces hyperventilation.