Expression of neuronal nicotinic acetylcholine receptors in rat vagal pulmonary sensory neurons

Abstract

It has been known that cigarette smoke inhalation causes airway irritation and cough, and the effect is primarily caused by a stimulatory effect of nicotine on bronchopulmonary sensory nerves. However, little is known about the expression of nicotinic acetylcholine receptors (nAChRs) in these afferents. In this study, whole‐cell patch‐clamp recording and RT‐PCR were carried out to examine the expression and function of nAChRs in isolated rat vagal pulmonary sensory neurons that were identified by retrograde labeling with a fluorescent tracer. Patch‐clamp recordings demonstrated that application of acetylcholine concentration‐dependently evoked an inward current in a subset of pulmonary sensory neurons, which was inhibited by hexamethonium. Application of nicotine or 1,1‐dimethyl‐4‐phenylpiperazinium (DMPP) also activated these neurons, evoking an inward current in voltage‐clamp configuration and causing depolarization and action potential in current‐clamp recordings. RT‐PCR analysis further demonstrated the expression of mRNA encoding for the nAChR subunits α4, α5, α6, α7, β2, β3 and β4, but not α2 and α3 in these neurons. In conclusion, our data have demonstrated the expression of neuronal nAChRs in rat vagal pulmonary sensory neurons. Supported by NIH HL067379 and Parker B. Francis Fellowship in Pulmonary Research.