[Involvement of pharyngeal muscles in compensatory responses of the respiration system to inspiration resistance load].

The present study was undertaken to test the hypothesis that recruitment of upper airway muscles in loaded breathing is a result of integration of peripheral chemoreceptor and pulmonary mechanoreceptor afferents. Experiments were performed in spontaneously breathing tracheostomized anesthetized rabbits. It had been studied the effects of inspiratory resistive loading to EMG activity of genioglossus muscle. In the intact rabbits the peak value and duration of inspiratory activity of genioglossus increased in loading. Imposition of resistive load in vagotomized animals did not evoke alteration in inspiratory activity of genioglossus in the first loaded breath. Hyperoxia decreased the response of genioglossus muscle to inspiratory loading and vagatomy. We conclude that hypoxic stimulation of peripheral chemoreceptors and decrease in volume-related afferent activity from pulmonary stretch receptors are major mechanisms of the upper airway muscle recruiment in inspiratory resistive loading.