Mechanoreceptor‐like nerve terminals in the visceral pleura: neurochemical coding

Information on the sensory innervation of the visceral pleura is sparse and conflicting, and the limited physiological studies have not provided conclusive data. The present investigation was designed to provide a comprehensive neurochemical characterization of the innervation of the visceral pleura. Multiple Immunostaining and confocal microscopy of whole mount preparations of rat visceral pleura revealed laminar receptor‐like nerve endings that regularly occurred in a widespread network of nerve fibers. The receptor end organs were invariably intermingled with elastic connective tissue fibers of the visceral pleura. The ‘pleura receptors’ could specifically be visualized by immunostaining for PGP9.5, vesicular glutamate transporters, calcium‐binding proteins, Na+/K+‐ATPase α3‐ir, and partly for P2X 3 ATP‐receptors. The nerve fibers that give rise to pleura receptors were shown to be myelinated, are non‐vagal and most likely spinal in origin. In conclusion, this study provides an unambiguous identification of well‐defined sensory receptors that are uniquely associated with the visceral pleura and reveal neurochemical features of myelinated mechanoreceptors. Furthermore, the use of whole mount preparations creates a good basis for further physiological studies. Support: Fund for scientific Research Flanders (G.0155.01 to D.A.); NOI‐BOF grant from the University of Antwerp (to D.A.)