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

We investigated the expression of three subunits of epithelial sodium channel (ENaC), αENaC, βENaC and γENaC, in the nodose ganglion and laryngeal mucosa of rat by RT-PCR analysis and immunohistochemistry. PCR products of predicted size for αENaC, βENaC and γENaC subunits were amplified from extract of nodose ganglion. Immunohistochemically, nodose ganglion neurons of medium to large diameter were immunoreactive for αENaC, βENaC and γENaC. In the deep region of laryngeal submucosal layer, thick nerve fibers without varicosities were immunoreactive for αENaC, βENaC and γENaC. In the laryngeal mucosa, terminal arborizations of the nerve endings, that immunoreacted for αENaC, βENaC and γENaC 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 βENaC and γENaC, but negative for αENaC. 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.