Functional properties of the Na^+-sensitive Na^+ channel in tanycytes

单细胞中 Na^ 敏感 Na^ 通道的功能特性

• 批准号: 14570042
• 负责人: YOSHIDA Shigeru
• 金额: $ 2.24万
• 依托单位: Kinki University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14570042/
• 关键词: mouse; tanycyte; Na^+-sensitive Na^+channel; Na^+ sensor; osmolality sensor; median eminence; ナトリウムチャネル; 濃度依存性

Methods : Brain slices, sectioned coronally at the level of the median eminence(ME) with 200μm thickness, were obtained from adult mice(C57BL/6J). Slices were loaded with the Na^+-sensitive fluorescent dye SBFI(sodium-binding benzofuran isophthalate), and intracellular Na^+ images were monitored using an image analyzer ARGUS-50(Hamamatsu Photonics, Japan).Resulfls : 1)In all areas studied, the intracellular Na^+ concentration([Na^+]_i) was greatly increased by 1mM ouabain(a Na^+ pump blocker). 2)[Na^+]_i was decreased either by 1-10μM benzamil(a blocker of Na^+/Ca^<2+> exchanger), 100μM amiloride(an inhibitor of epithelial Na^+ channels(ENaCs)) or 1mM phloridzin(a blocker of Na^+/ghicose co-transporter). 3)When [Na^+]_o was raised from a control value of 140mM to 160-200mM, a sustained elevation in [Na^+]_i was observed in ME but only small responses were observed in the other regions. 4)The responses were abolished when Na^+ was substituted with choline or mannitol. 5)Very small changes were seen in [Na^+]_i when [Na^+]_o was decreased from 140mM to 100mM. 6)The transitional area between the lateral wall of third ventricle (3V) and the ME responded inversely, i.e. this area showed a decrease in [Na^+]_i when [Na^+]_o was elevated.Conclusions : The data indicate that (a)the basal level of [Na^+]_i in the brain regions lining 3V and ME is maintained chiefly by Na^+ pumps, Na^+/Ca^<2+> exchangers, ENaCs and Na^+/glucose co-transporters, and (b)a Na^+-level sensor, present in ME where the blood-brain barrier is absent, works when [Na^+]_o Aviates from the maintained [Na^+]_i level.

方法：取成年小鼠(C57BL/6J)正中隆起(ME)水平的脑组织切片，厚200μm。将钠离子敏感的荧光染料SBFI(钠结合的苯并呋喃间苯二甲酸酯)加载到脑片上，用Argus-50图像分析仪监测细胞内Na+图像。结果：1)在所有研究区域，细胞内Na+浓度([Na+]i)显著增加1 mM哇巴因(一种Na+泵阻滞剂)。2)Na~+/Ca~(2+)交换阻断剂1-10μM苯扎米、上皮Na~+通道阻滞剂100μM阿米洛利或Na~+/Ghc共转运体阻断剂1 mM连翘苷均可使[Na~(++)]_i降低。3)当[Na~(++)]_o从对照的140 mm升高到160~200 mm时，ME的[Na~+]_i持续升高，其他区域仅有少量反应。4)用胆碱或甘露醇替代Na~+后，上述反应消失。5)当[Na~+]_o由140 mm降至100 mm时，[Na~+]_i变化很小。6)第三脑室侧壁(3V)与ME之间的过渡区反应相反，即[Na+]_o升高时，该区域[Na~+]_i降低。结论：(1)3V和ME脑区[Na~+]_i的基础水平主要由Na~+泵、Na~+/Ca~(2+)和GT维持；交换器、ENaCs和Na+/葡萄糖共转运体，以及(B)在没有血脑屏障的ME中存在的Na+水平传感器，当[Na^+]_o从维持的[Na^+]_i水平消失时，该传感器起作用。

项目成果

Hiyama, T.Y.(他6名): "Nax channel involved in CNS sodium-level sensing."Nature Neuroscience. 5. 511-512 (2002)

Hiyama, T.Y.（其他 6 人）：“Nax 通道参与中枢神经系统钠水平传感。”《自然神经科学》5. 511-512 (2002)

Ogata N., Yoshida S.: "New perspectives on the structure and function of sodium channel multigene family."Vol.2. 59-81 (2002)

Ogata N.，Yoshida S.：“钠通道多基因家族结构和功能的新视角”。第 2 卷。

Hiyama, T.Y., Watanabe, E., Ono, K., Inenaga, K., Tamkun, M.M., Yoshida S., Noda, M.: "Na_x channel involved in CNS sodium-level sensing."Vol.2. 511-512 (2002)

Hiyama, T.Y.、Watanabe, E.、Ono, K.、Inenaga, K.、Tamkun, M.M.、Yoshida S.、Noda, M.：“Na_x 通道参与中枢神经系统钠水平传感。”第 2 卷。

Ogata, N., Yoshida S.: "New perspectives on the structure and function of sodium channel multigene family."Current Medicinal Chemistry-Central Nervous System Agents. 2. 59-81 (2002)

Ogata, N.，Yoshida S.：“钠通道多基因家族结构和功能的新视角。”当前药物化学-中枢神经系统药物。

Ogata, N., Yoshida, S.: "New perspectives on the structure and function of sodium channel multigene family"Current Medicinal Chemistry -Central Nervous System Agents. 2. 59-81 (2002)

Ogata, N.，Yoshida, S.：“钠通道多基因家族结构和功能的新视角”当前药物化学-中枢神经系统药物。