Saito T, Ishikawa S E, Sasaki S, Fujita N, Fushimi K, Okada K, Takeuchi K, Sakamoto A, Ookawara S, Kaneko T, Marumo F, Saito T
Department of Medicine, Jichi Medical School, Tochigi, Japan.
Am J Physiol. 1997 Feb;272(2 Pt 2):F183-91. doi: 10.1152/ajprenal.1997.272.2.F183.
Dehydration increased the expression of aquaporin of collecting duct (AQP-2) and translocated AQP-2 to the apical plasma membranes from cytoplasmic vesicles of collecting duct cells. We determined whether the abrupt decrease in circulating arginine vasopressin (AVP) by giving excess water affects the expression of AQP-2 mRNA and subcellular localization of AQP-2 in collecting duct cells of the dehydrated rats. The 72-h water deprivation increased plasma AVP levels to 3.1 pg/ml and the expression of AQP-2 mRNA by 336% in rats, which were concomitantly abolished by the 40 ml/kg oral water load. A 50% inhibition ofAQP-2 mRNA expression was obtained with 20 min after the forced water load. In immunohistochemistry and electron microscopy, the AQP-2 was manifestly present around the apical edge of collecting duct cells in the 72-h dehydrated rats. The AQP-2 was diffusely translocated into the cytoplasm 1 h after the forced water administration. These results indicate that AVP plays the on-off regulation of AQP-2 mRNA expression and that a majority of AQP-2 is regulated by the shuttle recycling in the collecting duct cells.
脱水增加了集合管水通道蛋白（AQP-2）的表达，并使AQP-2从集合管细胞的细胞质囊泡转运至顶端质膜。我们研究了给予过量水分导致循环中精氨酸加压素（AVP）突然减少是否会影响脱水大鼠集合管细胞中AQP-2 mRNA的表达及AQP-2的亚细胞定位。72小时禁水使大鼠血浆AVP水平升至3.1 pg/ml，AQP-2 mRNA表达增加336%，而40 ml/kg口服水负荷可使其同时消除。强制水负荷后20分钟，AQP-2 mRNA表达受到50%的抑制。免疫组织化学和电子显微镜检查显示，72小时脱水大鼠的集合管细胞顶端边缘明显存在AQP-2。强制给予水分1小时后，AQP-2扩散至细胞质中。这些结果表明，AVP对AQP-2 mRNA表达起着开关调节作用，且集合管细胞中大部分AQP-2受穿梭循环调节。
