【摘要】 观察水通道蛋白1、4、5(AQP-1,4,5)在正常豚鼠中耳腔粘膜的表达和分布情况,探讨AQP-1,4,5在豚鼠中耳液体转运和水平衡中的作用机制.用逆转录聚合酶链反应(RT-PCR),免疫印迹(Western-blotting)和免疫组织化学的方法观察正常豚鼠中耳腔粘膜AQP1、4、5的表达和分布情况.AQP-1,4,5的mRNA在正常豚鼠中耳腔粘膜内有确定表达,AQP-1,4的蛋白质在正常豚鼠中耳粘膜内有确定表达,AQP-1的细胞定位发现:AQP-1在所有的中耳腔内被覆的扁平上皮,立方上皮,粘膜下层的毛细血管内皮和此层的纤维母细胞的胞浆中均有分布.AQP-1可能通过上述分布,在调节纤周粘液系统的厚度、粘膜下毛细血管与周围组织的水分交换、纤维母细胞层保持渗透压差的活动过程中与离子通道介导的离子流运动一起来积极参与中耳腔的水转运.由于相关基因和蛋白表达的存在,也初步揭示了AQP-4和AQP-5在中耳腔粘膜组织中可能存在.AQP-1,4,5共同参与了中耳腔的液体平衡过程,参与了保持中耳腔正常情况下的无液体积聚状态.更多还原

【Abstract】 Aquaporins (AQPs) are a growing family of small integral membrane proteins. Functional studies have demonstrated that AQPs operate like molecular water valves through regulated cellular expression within specific organs, allowing water to move along the osmotic gradient. AQPs are thought to play a vital role in water balance and be associated with disorders of water regulation in particular organs, such as the heart failure, hypertension, glaucoma, pulmonary edema, renal cyst. Secretory otitis media (SOM) is one of the most common diseases which can lead to the conducted hearing loss in human and animals for the effusion accumulation in the air-filled middle ear cavity, which can disturb the water balance and the cellular environment in middle ear. To explore the expression pattern of AQP-1,4,5 in the normal middle ear in guinea pigs and its roles in maintaining water homeostasis in the middle ear cavity., we observed the AQP1,4,5 expression in normal middle ear cavity of guinea pigs. Reverse transcriptase polymerase chain reaction (RT-PCR), Western blotting and immunohistochemical staining were used to detect AQP1,4,5 in the bullae of the guinea pigs. RT-PCR analyses revealed that mRNAs encoding AQP1,4,5 were expressed in middle ear membrane of the guinea pigs. And immunoblot detection showed that AQP1 and AQP4 were detected as 28-kDa and 33-kDa proteins in the middle ear cavities. Immunohistochemical analysis showed that AQP1 was localized at capillary endothelial cells and fibroblasts in the lamina propria mucosae as well as at flat and cubical epithelial cells. AQP1,4,5 were expressed in the membrane of the middle ear cavities in guinea pigs which implied they might take vital role on the water balance and keep the fluid-free state of the normal middle ear cavity. AQP1 may take part directly in the water transport by absorbing of the fluid in the cavity, regulating the amount and composition of the periciliary fluid layer, altering the permeability of the capillaries in lamina propria mucosae and contributing to the action of fibroblasts layers of keep the difference of osmotic pressure. AQP4 and AQP5 may perform their function in the ciliated epithelium which exists in both of the clearance systems in the middle ear. AQP1 might be responsible more for the formation of effusion. Our study suggests that Aquaporin-1,4,5 are expressed in the normal middle ear cavity of guinea pig and may play a vital role in the water transmission in the middle ear. The mechanism of their contribution to the water balance is presumably similar with that in lungs.更多还原