The long-term goal of this proposal is to better understand the cellular mechanisms, which regulate transepithelial water flux in the vocal fold. We hypothesize that aquaporin water channels, present in the plasma membrane of vocal fold epithelial cells, regulate osmostic transepithelial water fluxes of the vocal fold. If so, aquaporins may provide an intrinsic mechanism for regulation of vocal fold hydration and phonation. We will first demonstrate the presence of two aquaporin water channels in native vocal fold epithelial tissue via Western immunoblot analysis, followed by immunolocalization of the water channel proteins using immunogold labeling and transmission electron microscopy. The role of aquaporins in vocal fold transepithelial water fluxes will then be elucidated by imposition of osmotic gradients to the luminal epithelium. The dependence of aquaporin expression on the osmotic gradient will be demonstrated by Northern Blot analysis of mRNA expression of aquaporins and measuring associated transepithelial water fluxes. Data described here will contribute to knowledge of the flux of water across biological membranes as well as the cell biology of stratified squamous epithelial tissue, and may contribute to advances in clinical treatment of voice disorders.
