Expression of ENaC subunits in sensory nerve endings in the rat larynx

We investigated the expression of three subunits of epithelial sodium channel (ENaQ, alpha ENaC, beta ENaC and gamma ENaC, in the nodose ganglion and laryngeal mucosa of rat by RT-PCR analysis and immunohistochemistry. PCR products of predicted size for (alpha ENaC, beta ENaC and gamma ENaC subunits were amplified from extract of nodose ganglion. Immunohistochemically, nodose ganglion neurons of medium to large diameter were immunoreactive for alpha ENaC, beta ENaC and gamma EMC. In the deep region of laryngeal submucosal layer, thick nerve fibers without varicosities were immunoreactive for alpha ENaC, beta ENaC and gamma ENaC. In the laryngeal mucosa, terminal arborizations of the nerve endings, that immunoreacted for alpha ENaC, beta ENaC and gamma ENX were scattered in the lamina propria just beneath the epithelia of epiglottis and laryngeal vestibule. Double immunofluorescence with calretinin revealed that they were laminar nerve endings. Some thick nerve fibers near the laryngeal taste buds were also immunoreactive for beta ENaC and gamma ENaC, but negative for alpha ENaC. In the larynx, ENaC channels may play important roles in mechanotransduction in the laminar endings and in the mechano- and chemotransductions in the taste bud-associated nerve fibers. (c) 2006 Elsevier Ireland Ltd. All rights reserved.