Airway mucus is regulated by many inflammatory mediators such as ILs, TNF-alpha, EGF, PGF2 alpha, LT, and so on. Recently, the relationship between membrane ion channel and Mucus production has been under investigation. The present study aimed to examine whether AQP5 was involved in modulation of mucin expression and secretion in airway submucosal gland cells (SPC-Al). A recombinant plasmid (pShAQP5) containing small hairpin RNA expression cassette targeting AQP5 sequence was constructed. In pShAQP5 transiently transfected cells, ELISA showed MUC5AC synthesis and secretion were increased by 57.9% and 85.3%, respectively, on day 5 after pShAQP5 transfection. While in five stably transfected clones (shAQP5-G1, G2, G3, A2, and A5), the upregulated levels of M MAC mRNA were 118%, 165%, 65% 123%, and 38%, respectively. The elevated levels of M MAC synthesis and secretion varied from 59-156% and 33-166%, respectively. This is the first reliable investigation of the regulation of MUC5AC mucin secretion by silencing AQP5. Further study of the regulatory mechanism between AQPs and mucins may provide new strategies for development of novel antihypersecretory drugs in airway diseases. (c) 2006 Elsevier Inc. All rights reserved.