Differences in bioelectric responses to hyperosmolarity in epithelium of fresh tracheal segments (FE) and air-liquid interface epithelial cell cultures (CE) from guinea pigs.
Fedan JS; Wu D; Van Scott MR
Pharmacologist, XIV World Cong Pharm, July 7-12, 2002, San Francisco, California. Bethesda, MD: The American Society for Pharmacology and Experimental Therapeutics, 2002 Jul; 44(2)(Suppl 1):A226
In guinea-pig perfused trachea preparations, application of methacholine (MCh) to the serosal surface elicits contraction of the airway smooth' muscle. Increasing the tonicity of the modified Krebs-Henseleit solution (MKHS) bathing the epithelium with D-mannitol (D-M) causes an epithelium-dependent relaxation. In this study, we compared bioelectric responses of FE and CE (30% ciliated cells) to these agents using Ussing chambers. When applied to the serosal surface of FE, MCh (3 10-7 M) elicited a smooth, monotonic increase in short circuit current (Isc). The subsequent addition of D-M (0.27 - 266.8 mosM added) to the mucosal MKHS of FE elicited D-M concentration-dependent decreases in Isc. In contrast to responses of FE, CE responded to the serosal application of MCh with a rapid, transient increase in Isc, which was followed by a sustained plateau. Also in contrast to responses of FE, cumulative increases in osmolarity with D-M (0.27-84.3 mosM) added to the mucosal compartment led to increases in Isc, but further increasing the osmolarity(84.3266.8 mosM) decreased Isc and decreased transepithelial resistance concomitantly. The change in the responses of CE might reflect the absence of released or constitutive substances in the airway wall, or a phenotypic modification occurring under culture conditions.
Bioelectric effects; Cell cultures; Laboratory animals; Animal studies; Animals; Muscles; Airway obstruction; Airway resistance
Jeffrey S. Fedan, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505
The Pharmacologist, The XIVth World Congress of Pharmacology