Expression of water channel proteins (aquaporins) in the rat Eustachian tube and middle ear mucosa

Sung Ho Kang, Ki Hong Chang, Shuji Ohcho, Haa Yung Lee, Kiweon Cha, Sung Kyun Moon, Ali Andalibi, David J. Lim

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Conclusion. Diverse expression of the different subtypes of aquaporins in different parts of the Eustachian tube and middle ear suggests region-specific functions of the aquaporins in the normal physiology of the tubotympanum and also suggests that they may play roles in the pathophysiology of otitis media. Objectives. The epithelial cells of the middle ear and Eustachian tube must maintain adequate water balance for normal function of the mucociliary system. Since aquaporins (AQPs) are known to play critical roles in water homeostasis, we investigated their expression in the tubotympanum of the rat. Methods. The expression of AQP subtypes 1, 2, 4, 5, and 7 were examined in the rat Eustachian tube and middle ear using RT-PCR, Western blotting, and immunohistochemistry. Results. Transcripts for AQP 1, 4, and 5 were detected in the Eustachian tube and middle ear. Expression of these molecules at the protein level was confirmed by Western blot analysis. Immunohistochemical analysis demonstrated that AQP 4 was localized to the basolateral membranes of ciliated epithelial cells while AQP 5 was localized to the apical surface of serous gland cells, but not goblet cells, in the rat Eustachian tube. AQP 1 was found to be expressed by the subepithelial fibroblasts.

Original languageEnglish (US)
Pages (from-to)687-692
Number of pages6
JournalActa Oto-Laryngologica
Issue number7
StatePublished - 2007


  • Aquaporins
  • Mucociliary system
  • Mucous blanket
  • Tubotympanum
  • Water channels

ASJC Scopus subject areas

  • Otorhinolaryngology


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