Effect of ion transport inhibitors on the bioelectric responses of guinea-pig tracheal epithelium to hypertonic sodium chloride solution.
Johnston-RA; Van Scott-MR; Rengasamy-A; Fedan-JS
FASEB J 2001 Mar; 15(5):A861
Previously our laboratory has shown that in the presence of serosally-added methacholine (MCh: 3x10^2 M), the application of hypertonic D-mannitol solution (120 mOsm) to the mucosal surface of guinea-pig tracheal segments mounted in Ussing chambers decreased the transepithelial short-circuit current (Isc). The purpose of this study was to determine if Isc responses to elevated tonicityare independent of the osmolyte used and to elucidate which epithelial ion channels and/or transporters are involved in the epithelial bioelectric response to elevated mucosal tonicity. In the presence of serosally-added MCh (3x10 M), exposure of the mucosal surface to modified Krebs-Henseleit solution made hypertonic with added NaCl (120 mOsm) decreased the Isc. Both amiloride (3x10^5 M; mucosal) and bumetanide (10^5 M; serosal) attenuated the decrease in Isc. Iberiotoxin (10 M: serosal and mucosal) a Ca activated K* channel blocker had no effect on Isc. The Isc increased rather than decreased in the presence of the Cl channel blocker. NPPB (10^-4 M: mucosal). The effect of ouabain (10 M: serosal) a Na-K*-ATPase inhibitor was also examined: however, it caused a progressive reduction in Isc which prevented assessment of the response to NaCl. These results suggest that apical Na channels and the basolateral Na-K-2Cl cotransporter are important in the epithelial bioelectric response to elevated mucosal tonicity while the role of apical Cl channels in this response is unclear.
Ion-transport; Bioelectric-effects; Sodium-compounds; Chlorides; Methacholines; Laboratory-animals; Animals; Animal-studies
Abstract; Conference/Symposia Proceedings
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