Research on regulatory mechanism of ion transport in the endolymphatic sac and its distubance
Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
Date (from‐to) : 2004 -2006
Author : MORI Nozomu; MIYASHITA Takenori
(Microfluorometrical study on ion channel in the ES)
The dynamic properties of sodium transport in the endolymphatic sac (ES) were investigated using SFBI/AM fluorescence measurement. The intracellular Na^+ concentration was measured in freshly dissected ES sheet from the intermediate portion of the ES of the guinea pig. The results showed the strong relationship between Na^+, K^+ATPase activity and mitochondrial staining, suggesting that mitochondria-rich ES epithelial cells (Type 1 cells, ca. 30% of ES cells) endowed with high Na+ permeability and Na^+, K^+-ATPase activity potentially contribute to sodium transport of the ES.
(Molecular biological study of ion channels and ion transporters)
The presence of Na-K-2Clcotransporter(NKCC) and P_<2Y> receptor and their subtypes in the ES of the rat was examined by molecular biological techniques. RT-PCR showed the presence of two subtypes of NKCC (NKCC1 and NKCC2) and four subtypes of P<2Y> receptor (P_2Y_1,P_2Y_2,P_2Y_4,P_2Y_6). The presence of NKCC2 (peculiar to the kidney) in the ES strongly suggests the absorptive function of the ES. RT-PCR confirmed the presence of P2Y receptors suggested by our previous electrophysiological study. We are now examining the localization of NKCC and P_<2Y> receptor in the ES.