The transduction properties of diaphragmatic mechanoreceptors

The transduction properties of diaphragmatic mechanoreceptors were studied using an isolated organ preparation. Following localization of their receptive field and receptor characterization, controlled diaphragmatic stretch in 2 mm increments was performed while recording the steady-state firing frequency of these afferents. Of 31 receptors recorded, 14 could be categorized into one of 3 types: (1) muscle spindles, (2) Golgi tendon organs, and (3) pressure-sensitive mechanoreceptors. These receptors were also found to be widely distributed in the diaphragm. Four of the muscle spindles examined were shown to possess a length sensitivity of 4-8 mm with a wide range of maximal discharge. The results of this study suggest that the diaphragm contains mechanoreceptors that transduce muscle length and projects this information regarding respiratory proprioception to the CNS.