[Significance of the lung mechanoreceptors in shortening expiration during lung collapse]

In 24 vagotomized cats, changes of impulse activity of 50 stretch receptors were studied in equal extent of lung collapse but under different conditions: in sucking off of air from lungs with obstructed trachea and in pneumothorax. In small lung collapse the sensory inputs during expiration under sucking off of air was by 38-47% greater than under pneumothorax whereas the amount of the receptors with arrested impulse activity as well as the firing rate were lesser than under pneumothorax. In an increased lung collapse the intensities of sensory inputs under these two conditions were only slightly different. As the expiration shortening in pneumothorax is more obvious than under sucking off of air, the data obtained suggest a participation of fast-adapting (irritant) lung receptors in the mechanisms of the expiration shortening in lung collapse.