内リンパ嚢におけるNa⁺-K⁺-ATPaseの分布

抄録

Regulation of ion composition in the endolymph has been thought to occur mainly at the stria vascularis and the endolyphatic duct (ED) or sac (ES). And, the low level of K⁺ in the ES makes a sharp contrast with the high level in the cochlear duct. This difference may be explained by the ultramorpho-logical observation that the K⁺ of the ES was absorbed by the ED. On the other hand, there is a report showing the localization of Na⁺-K⁺ ATPase in the ES by enzyme-histochemical methods. This fact suggests that active transport takes place in the ES. Probably the ED and ES have several functions to regulate ion composition. Enzyme histochemistry does not seem sensitive enough to know the accurate localization of this enzyme. In this study using an immunohistochemical technique (immunofluorescence or ABC method), we could clearly demonstrate it along the basolateral membrane of the guinea pig ES epithelium. It was absent on the luminal side of the epithelium. These findings indicate that ion regulation in the ES may have a bearing in part on the low level of K⁺ in this organ. Further studies are essential for the clarification of the role of this enzyme in the ES in due consideration of the functions of the ED.