Talbot Neil C, Garrett Wesley M, Caperna Thomas J
Gene Evaluation and Mapping Laboratory, Beltsville Agricultural Research Center, Beltsville, MD 20705, USA.
Cells Tissues Organs. 2003;174(3):117-28. doi: 10.1159/000071152.
Aquaporins (AQPs) are cellular proteins involved with the movement of water across cell membranes and are fundamentally important to the fluid transport in the bile ducts and ductules of the liver. An immunohistochemical analysis of AQP-1 and AQP-9 was undertaken to describe their expression in fetal and adult pig liver, while immunoreagents specific to some other AQPs were screened for their efficacy on pig liver tissues. Anti-AQP-1 antibody reacted with the bile duct of the portal space and the bile ductules at the periphery of the liver lobules. Histological identification of bile ductules was confirmed by positive reactivity with anti-cytokeratin-7 and antilaminin immunostaining. Anti-AQP-1 signals were also pronounced in the endothelium of the portal space blood vessels and peripheral distributing venules. Antibody to AQP-9 reacted strongly with small ductules peripheral to the liver lobules, but only weakly with the bile ducts of the portal space. Anti-AQP-adipose antibody bound to the smooth muscle cells of the arteries in the portal space and sporadically with certain binucleated cells in the liver lobule. Antibodies to AQP-3, AQP-4, AQP-7, and AQP-8 were nonreactive with any of the tissues of the adult pig liver. For comparative purposes, immunohistochemical analysis of rat liver tissue was done with the anti-AQP-1 and AQP-9 antibodies. Anti-AQP-1 reacted weakly with the rat liver's bile ducts, but robustly with the endothelium of the liver's veins and arteries. It also reacted strongly with the central vein of the rat liver lobules, and, because the staining was continuous with hepatic sinusoids, it appeared that the reactivity was specific to the endothelial cells. Anti-AQP-9 antibodies reacted with rat hepatocytes and was not associated with the canaliculi, as judged by concurrent phalloidin staining of actin. The results indicate that specific AQPs are expressed in the tissues of the pig liver and that AQP-9 expression is distinct from its expression in the rat liver.
水通道蛋白（AQPs）是参与水跨细胞膜转运的细胞蛋白，对肝脏胆管和胆小管中的液体运输至关重要。进行了AQP - 1和AQP - 9的免疫组织化学分析，以描述它们在胎儿和成年猪肝中的表达，同时筛选了针对其他一些AQPs的免疫试剂对猪肝组织的有效性。抗AQP - 1抗体与门管区的胆管和肝小叶周边的胆小管发生反应。通过与抗细胞角蛋白 - 7和抗层粘连蛋白免疫染色的阳性反应证实了胆小管的组织学鉴定。抗AQP - 1信号在门管区血管内皮和周边分布的小静脉中也很明显。AQP - 9抗体与肝小叶周边的小胆管强烈反应，但与门管区的胆管反应较弱。抗AQP - 脂肪抗体与门管区动脉的平滑肌细胞结合，并偶尔与肝小叶中的某些双核细胞结合。抗AQP - 3、AQP - 4、AQP - 7和AQP - 8抗体与成年猪肝的任何组织均无反应。为作比较，用抗AQP - 1和AQP - 9抗体对大鼠肝脏组织进行了免疫组织化学分析。抗AQP - 1与大鼠肝脏的胆管反应较弱，但与肝脏静脉和动脉的内皮反应强烈。它也与大鼠肝小叶的中央静脉强烈反应，并且由于染色与肝血窦连续，似乎这种反应性是内皮细胞特有的。抗AQP - 9抗体与大鼠肝细胞反应，并且根据肌动蛋白的同时鬼笔环肽染色判断，与胆小管无关。结果表明，特定的水通道蛋白在猪肝组织中表达，并且AQP - 9的表达与其在大鼠肝脏中的表达不同。
