Mechanism of water transport; Elucidation of brain edema and development of treatment.

本研究采用原代培养的视网膜神经胶质细胞Muller细胞，研究了水通道蛋白4在视网膜神经胶质细胞中的分布。当细胞在聚赖氨酸包被的玻璃上培养时，AQP4定位于细胞质中。结果：在细胞膜上未见AQP4的表达。然而，当Muller细胞种植在层粘连蛋白涂层的玻璃上时，在膜上发现了AQP4。在甲状腺素激酶抑制剂Herbimycin存在下，Muller细胞膜上的AQP4表达消失。细胞外基质通过酪氨酸激酶的功能调节细胞膜上水通道的表达。因此，脑损伤引起细胞外基质功能紊乱可能影响AQP4的表面表达，导致水平衡失调。水的运输伴随着离子的运输。先前的实验表明，K^+通道对于水分运输是重要的。我们研究了ATP敏感性K^+通道（KATP通道），因为当细胞受损时，KATP通道会打开。我们发现KATP通道在神经元中有表达。KATP通道各亚家族在同一神经元中的表达不同。我们发现SUR1亚单位存在于神经炎的胞体中，而SUR2亚单位则位于神经炎的末梢。KATP通道亚基表达的差异可能反映了KATP通道亚基的功能差异。

We have studied the distribution of AQP4 water channel in Muller cells, dominant glial cells of the retina, using primary culture of Muller cells. When the cells were cultured on poly lysine-coated glass, AQP4 located in the cytoplasm. We could not find any expression of AQP4 on the membranes. However, when Muller cells were planted on laminine-coated glass, AQP4 was found on the membranes. Expression of AQP4 on the membranes of Muller cells disappeared in the presence of Herbimycin, a thyrosine kinase inhibitor. Extracellular matrix regulates water channel expression on the membranes through the function of a tyrosine kinase. Thus, brain damage causing functional disorder of extracellular matrix may affect surface expression of AQP4 and induce unbalance of water. transport.Water transport is accompanied with ion transport. Previous experiment showed K^+ channels are important for water transport. We have studied ATP sensitive K^+ channels(KATP channels), because KATP channels open when cells have damage. We found that KATP channels expressed in neurons. Expression of subfamily of KATP channels was different in a neuron. We found that SUR1 subunit existed in the cell body, while SUR2 subunit located in terminals of neuritis. The difference of expression may indicate functional difference of KATP channel subunit.