2003 Fiscal Year Final Research Report Summary
Research on sodium transport in the endolymphatic sac
| Project/Area Number |
13671783
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Otorhinolaryngology
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| Research Institution | Kagawa University(Faculty of Medicine) |
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Principal Investigator |
MORI Nozomu Kagawa University, Faculty of Medicine, Professor, 医学部, 教授 (90124883)
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| Co-Investigator(Kenkyū-buntansha) |
MIYASHITA Takenori Kagawa University, University Hospital, Assistant, 医学部附属病院, 助手 (60363214)
HOSHIKAWA Hiroshi Kagawa University, University Hospital, Assistant Professor, 医学部附属病院, 講師 (70294767)
FURUTA Hiroshi Kagawa University, Faculty of Medicine, Associate Professor, 医学部, 助教授 (90209180)
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| Project Period (FY) |
2001 – 2003
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| Keywords | endolymphatic sac / epithelial cell / sodium ion transport / patch clamp technique / SFBI / AM fluorescence measurement / intracellular calcium / mitochondria stain |
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| Research Abstract |
(Study on non-selective cation channel in the ES) The properties of a non-selective cation channel in the endolymphatic sac (ES) were investigated using patch clamp technique. The channel currents were measured in freshly isolated epithelial cells from the intermediate portion of the endolymphatic sac (ES) in the guinea pig by the single-channel recording technique. The non-selective cation channel had a conductance of 24.0? 1.3pS (n=8). The relative ionic permeability of the channel was in the order K^+=Na^>Ca^<2+>>Cl^-. ATP (1 mM) activated the channel at intracellular Ca^<2+> concentrations from 0.6 iM to 10iM. The results suggest that the non-selective cation channel in the ES may contribute to the regulation of ionic balance and volume of the ES by absorbing Na^+ under certain pathological situations increasing the intracellular Ca^<2+> concentration.
(Microfluorometrical study on Na+ transport in the ES) The properties of Na+ transport in the ES epithelial cells were investigated using SFBI/AM fluorescence measurement. The intracellular Na concentration was increased by the suppresion of Na^+-K^+ ATPase such as the application with K^+-free solution and ouabain. ES epithelial cells in the intermediate portion were classified into two types, based on the activity of Na^+-K^+ ATPase. Two type cells were almost equally distributed in number. The epithelial cells with a higher activity corresponded to strongly mitochondria-stained cells (type 1cells). The results indicates that type 1cells play important roles in sodium transport of the ES. The simulation of Na transport capacity in the ES epithelial cells on the basis of the present experimental results supports the morphological data in the experimentally induced endolympatic hydrops.
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