Bioelectric responses of guinea-pig tracheal epithelium to hyperosmolar and isosmolar challenges.
Wu-DXY; Johnston-RA; Van Scott-MR; Fedan-JS
Am J Respir Crit Care Med 2002 Apr; 165(8)(Suppl.):A66
In the isolated, perfused guinea pig-trachea preparation mucosal perfusion with hyperosmolar solution causes relaxation of airway smooth muscle mediated by epithelium-derived relaxing factor (EpDRF) and associated with transepithelial depolarization, We investigated bioelectrical responses of epithelium to hyperosmolar and isosmolar solutions in tracheal segments mounted in Ussing Chambers. Hyperosmolar solution consisted of modified Krebs-Henseleit solution (MKHS; 281 momM) + 281 mosM of osmolyte in water. Both types of solutions are known to elicit cell shrinkage. Hyperosmolar D-mannitol (D-M) elicited a rapid decrease in short circuit current (Isc). Substituting gluconate for CI- in the MKHS reduced the change in Isc by 40%. Mucosal exposure to hyperosmolar or isosmolar NMDG-gluconate (NMDG-Glu) also caused a rapid decrease in Isc. To test whether hyperosmolar NMDG-Glu solution could elicit further responses, NMDG-Glu was added to isosmolar NMDG-Glu solution to double its osmolarity (562 mosM). The Isc responses to this challenge varied: an initial decrease followed by and increase, a decrease, or no effect, were seen. Mucosal hyperosmolar NaCl increased Isc whereas isosmolar NaCl decreased Isc. The results indicate that the bioelectric effects of apical isosmolar NMDG-Glu differ from that of NaCl, perhaps because of differences in the gradient driving Na+ absorption. Cl- plays a key role in the bioelectric response of tracheal epithelium to hypertonic challenge.
In-vitro-study; Bioelectric-effects; Cellular-reactions; Cell-cultures
Abstract; Conference/Symposia Proceedings
American Journal of Respiratory and Critical Care Medicine, 2002 International Conference, The American Thoracic Society, Atlanta Georgia, May 17-22, 2002