The roles of aquaporin water channels in the regulation of water transport across the plasma membrane of heart muscle cells.

水通道蛋白水通道在调节水穿过心肌细胞质膜运输中的作用。

• 批准号: 13670751
• 负责人: OGURA Toshitsugu
• 金额: $ 1.86万
• 依托单位: KANAZAWA MEDICAL UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13670751/
• 关键词: Aquaporin water channels; Water permeability coefficient; Membrane transport; Cell volume regulation; Osmolality; Heart muscle; Protein kinase A; Protein phosphorylation; 水透過係数; Protein kinase A; イオン・チャネル; ナトリウム・ポンプ

Water is in thermodynamic equilibrium across the plasma membrane of animal cells. When internal or external osmolality is altered, rapid transmembrane water flow occurs and the equilibrium is restored. In this research aimed at investigating (I) osmometric and water-transporting properties of rat and guinea-pig heart cells, (ii) regulation of sarcolemmal water transport by protein phosphorylation and (iii) cell volume-dependent changes in cardiac electrophysiological activities, several lines of new findings were obtained :1. Superfusion with anisosmotic solution (0.5-4 times normal osmolality) caused a rapid and reversible cell swelling or shrinkage. The osmotic water permeability coefficients (P_f) obtained by videomicroscopic analysis of cell surface dimensions (20-30 μm-s^<-1> at 35℃) was 10-20 times smaller than that of specialized water-transporting tissues (e.g., renal tubules, erythrocytes) ; its Arrhenius activation energy, a measure of the energy barrier to water flux, was as … More low as the value for free water diffusion (【approximately equal】4 kcal mol^<-1>).2. Treatment with Hg^<2+>, a sulfhydryl-oxidizing reagent, reduced P_f by 【approximately equal】80%, and the sulfhydryl-reducing reagent dithiothreitol antagonized the inhibitory action of Hg^<2+>. Inhibitors of volume-sensitive ion transports (DIDS, Gd^<3+>, and ouabain) modified the size of osmotic cell swelling but had little effect on P_f.3. Activation of adenylate cyclase with forskolin (FSK) caused a dose-dependent increase in P_f (EC_<50> 0.5 μM), whereas the adenylate cyclase-inactive analogue 1,9-dideoxy-FSK had no significant effect on P_f.4. Stimulatory action of FSK was mimicked by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine and the membrane permeable dibutyryl-cAMP. Treatment with the muscarinic agonist Ach or the PKA inhibitor H-89 antagonized the FSK-induced increase in P_f.5. These data indicate that osmotically-induced water flux across the plasma membrane of mammalian heart cells occurs mainly through aqueous pores and is regulated via a PKA-mediated mechanism that may involve phosphorylation of the water channel aquaporin. Redistribution of water changes cell volume, thereby diluting/concentrating the cytoplasmic constituents, and contributes to modified electrical (membrane potential and ionic currents) and contractile activities. Less

水在动物细胞的质膜上处于热力学平衡。当内部或外部渗透压发生改变时，会发生快速的跨膜水流并恢复平衡。本研究旨在探讨(1)大鼠和豚鼠心脏细胞的渗透和水转运特性，(2)蛋白质磷酸化对肌层水转运的调节，(3)心脏电生理活动中细胞体积依赖性的变化，获得了几条新发现：异渗溶液（0.5-4倍于正常渗透压）的超渗引起细胞迅速和可逆的肿胀或收缩。通过对细胞表面尺寸（35℃时为20 ~ 30 μm-s^<-1>）的视频显微镜分析得到的渗透水渗透系数（P_f）比肾小管、红细胞等特化输水组织小10 ~ 20倍；它的阿伦尼乌斯活化能（衡量水通量的能垒）为…，比水的自由扩散值（【约等于】4千卡mol^<-1>）要低。巯基氧化剂Hg^<2+>可使P_f降低80%，巯基还原剂二硫苏糖醇可拮抗Hg^<2+>的抑制作用。体积敏感离子转运抑制剂（DIDS、Gd^<3+>和乌阿巴因）可以改变渗透细胞肿胀的大小，但对P_f.3影响不大。用福斯克林（FSK）激活腺苷酸环化酶可引起P_f （EC_<50> 0.5 μM）的剂量依赖性增加，而腺苷酸环化酶无活性类似物1,9-二脱氧-FSK对P_f.4无显著影响。磷酸二酯酶抑制剂3-异丁基-1-甲基黄嘌呤和膜透性二丁基- camp模拟了FSK的刺激作用。毒蕈碱激动剂Ach或PKA抑制剂H-89可拮抗fsk诱导的P_f.5升高。这些数据表明，渗透诱导的水通量通过哺乳动物心脏细胞的质膜主要通过水孔发生，并通过pka介导的机制进行调节，该机制可能涉及水通道水通道蛋白的磷酸化。水的重新分配改变了细胞体积，从而稀释/浓缩了细胞质成分，并有助于改变电（膜电位和离子电流）和收缩活动。少

项目成果

T. Ogura et al.: "PKA-mediated regulation of water transport across rat heart cell membranes"Japanese Journal of Physiology. 52(Suppl). S71 (2002)

T. Ogura 等人：“PKA 介导的跨大鼠心脏细胞膜水运输的调节”日本生理学杂志。

小倉, 敏嗣: "高浸透圧灌流下でのモルモット心室筋細胞容積縮小と過分極"心電図. 21・5. 715 (2001)

Ogura，Toshitsugu：“高渗灌注下豚鼠心室肌​​细胞的体积减少和超极化”心电图 21・5（2001）。

T, Ogura: "Sarcolemmal hydraulic conductivity of guinea-pig and rat ventricular myocytes"Cardiovascular Research. 54(3). 590-60 (2002)

T，Ogura：“豚鼠和大鼠心室肌细胞的肌膜水力传导率”心血管研究。

T. Ogura et al.: "Osmotic water permeability across rat heart cell membrane"Japanese Journal of Physiology. 51(Suppl). S131 (2001)

T. Ogura 等人：“大鼠心脏细胞膜的渗透水渗透性”日本生理学杂志。

T, Ogura: "Osmotic water permeability across rat heart cell membrane"Japanese Journal of Physiology. 51(Suppl). S131 (2001)

T，Ogura：“大鼠心脏细胞膜的渗透水渗透性”日本生理学杂志。