Expression Pattern of Aquaporin 1 in the Middle Ear of the Guinea Pig with Secretory Otitis Media

OBJECTIVE: To explore the pathological change of water homeostasis in the secretory otitis media (SOM) middle ear, we observed the expression and regulation of aquaporin 1 (AQP1) in the SOM middle ear cavity. METHODS: Reverse transcriptase polymerase chain reaction (RT-PCR), Western blotting and immunohistochemical staining were used to detect AQP1 in the bullae of SOM models and normal animals. The expression patterns of AQP1 in the SOM group were compared with those in the normal animal group. RESULTS: RT-PCR and immunoblot analyses revealed that mRNAs encoding AQP1 were expressed in the middle ear membrane of the guinea pigs of both groups; AQP1 was also detected as 28-kDa proteins in both groups. Immunohistochemical analysis showed that AQP1 was localized on capillary endothelial cells and fibroblasts in the lamina propria mucosae as well as on flat and cubical epithelial cells. Quantitative analysis of RT-PCR and Western blotting revealed that AQP1 expression was higher in the SOM group than in the control group. The cellular expression of AQP1 was somewhat altered in the SOM middle ear. CONCLUSIONS: Our study suggests that AQP1 in the middle ear cavity may play a vital role in the accumulation of the effusion. It might work on the vessel-caused hydrops in the middle ear cavity.