Abstract
Observations were made on the cutaneo-respiratory reflex in rabbits by pneumograms and electromyograms (EMG).
A single tactile stimulation delivered to the inner side of the earlobe accelerated the depth and rate of respiration. When a relatively intense stimulation was delivered, the pneumogram shifted towards the inspiratory side. EMG changes were observed with stimulation hardly strsong enough to produce any changes in the pneumogram. An increase in the unit discharge frequency and recruitment of both inspiratory and expiratory neuromascular units were observed by a single tactile stimulation. Such stimulation brought out not only a reduction in the length of the discharging phase of both inspiratory and expiratory neurons, but also a reduction in that of the resting phase in the respiratory cycle.
Clasping the earlobe with a clip elicited an augmentative on-effect in the pneumogram and EMG. This effect was of exactly the same nature as that yielded by a single tactile stimulation. This initial on-effect, however, was followed by reduction of the depth and rate of respiration. Corresponding to this depression, decrease in the frequency of unit-discharge and recruitment of both inspiratory and expiratory neurons were observed in the EMG, and prolongation of the resting phase of the discharge was observed in the respiratory cycle. These depressive effect probably are produced by the pressure stimulation which is of spatio-temporally constant intensity delivered by clasping with a clip. By removal of the clip, an augmentative off-effect, which is the same as the on-effect, was seen.
As the pressure stimulation was delivered by cutaneous clipping, pain stimulation which produce the “ first pain ” may have combined to cause the on-and off-effects. On the other hand, the inhibitory response following the on-effect may have been caused not only by the afferent impulses of pressure receptors but also by those which evoke the “ second (slow) pain”.
Both of these augmentative and inhibitory cutaneo-respiratory responses decreased considerably by bilaterally sectioning the lung vagi in the neck. Thus, the cutaneo-respiratory reflex appears to be regulated by the vagal respiratory reflex.
