Upper and Lower Airways’ Receptors in Respiratory Load Perception

Abstract

There is clear evidence on the cortical somato-sensory representation of vagal afferents both from the thoracic and abdominal viscera (possibly including afferents from the lower airways) and the. larynx (Aubert & Guilhen, 1971). There is also evidence of a respiratory-related electrical activity evoked in humans in the region of the somatosensory cortex by inspiratory mechanical loading (Davenport et al., 1986). To what extent afferents from the lower and upper airway contribute to this sensory representation is not yet known. However, we do know that mechanical loading of the respiratory system has a considerable effect on the afferent activity originating from the lower and upper airways. This is already apparent from recording taken from the peripheral cut end of the entire cervical vagus nerve and superior laryngeal nerve (Fig. 1). This experiment shows that the activities of both nerves is markedly modified by an upper airway occlusion. As compared to control breathing, there is a strong augmentation in SLN discharge, but a conspicuous decrease of the vagal burst. Reasons for this discrepant behavior can be found in the transducing properties of laryngeal and tracheo-bronchial receptors and in the different mechanical circumstances that exist in the upper and lower airway.