A single pulmonary mechano-sensory unit possesses multiple encoders in rabbits.

Morphological studies have shown that axons of slowly adapting pulmonary stretch receptors (SARs) may supply more than one receptor structure. Thus, a single-unit of SARs may contain multiple encoders. We recorded SAR activities and searched for multiple receptive fields (MRFs) by probing the lung in anesthetized, open-chest and mechanically ventilated rabbits. One-third of SARs had clear MRFs. Selectively blocking fields with lidocaine, we found that each has its own encoder and discharge characteristics. Unit activity of SARs results from encoder interactions and undergoes significant integration before reaching the central nervous system.