Decreased connexin 43 (Cx43) expression as a result of application of lipopolysaccharide (LPS) may limit the diffusion of intercellular signaling molecules that is essential to the coordinated function of neighboring cells. Therefore, it may be related to a ciliary beating defect in nasal epithelial cells and result in accumulation of harmful substances.Gap junction intercellular communication (GJIC) is altered during inflammation in tracheal epithelial cells. Thus, we aimed to investigate whether LPS affects the expression of Cx43, the elementary protein composing the gap junction of nasal epithelial cells, in vitro.LPS (Pseudomonas aeruginosa serotype 10) was applied to epithelial cells obtained from nasal polyp for 24 h in vitro. As an inflammatory indicator, IL-8 secretion was measured using a commercially available ELISA kit. Cx43 protein was detected semi-quantitatively using Western blotting. The nasal epithelial cells constitutively secreted IL-8 at a concentration of 0.45+/-0.03 ng/microg protein. In the presence of 10(-2) mg/ml LPS, the concentration of IL-8 was significantly increased to 0.55+/-0.05 ng/microg protein (n=8). Expression of the Cx43:beta-actin ratio decreased in a time- and dose-dependent fashion (10(-3)-10(-1) mg/ml LPS).