Distribution of endothelin-1 like activity in the endolymphatic sac of normal guinea pigs

Endothelin-1 (ET-1), originally characterized as a 21-residue vasoconstrictor peptide from endothelial cells, has been reported to act as a local hormonal regulator of pressure, fluid, ions as well as neuropeptides. The present study investigated the distribution of ET-1 in the endolymphatic sac and duct of normal guinea pigs, by immunohistochemistry. ET-1 like activity was identified in the epithelial cells and subepithelial connective tissue of the endolymphatic sac and duct. No significant difference was seen in the intermediate and proximal portions. These findings suggest that ET-1 may play an important role in the regulation of inner ear pressure, fluid volume, and ion balance.