Chloride and sodium transport across bovine tracheal epithelium: effects of secretagogues and indomethacin.

The regulation of ion transport in bovine tracheal epithelium was studied in vitro. In the absence of exogenous modifiers of ion transport, average values for transepithelial electrical potential difference (psi t), short-circuit-current (Isc) and tissue resistance (Rt) were 35.4 mV (lumen negative), 5.4 muEq X h-1 X cm-2 and 187 omega X cm2 respectively; net Cl secretion (3.2 muEq X h-1 X cm-2) and net Na absorption (1.3 muEq X h-1 X cm2) accounted for 82% of the Isc. Amiloride reduced psi t and Isc, and increased Rt. The values of psi t, Rt and Isc obtained following addition of theophylline, epinephrine or prostaglandin E1 (PGE1) were not different from control values. Theophylline also did not alter Na and Cl fluxes but it increased tissue cAMP content 3-fold. Indomethacin did not affect psi t but it increased Rt and net Na absorption, and decreased Isc and net Cl secretion; it did not significantly reduce tissue cAMP. When added to indomethacin-treated tissues, epinephrine restored Isc, Rt and Na and Cl fluxes to control levels and increased tissue cAMP 3-fold. Similarly, when PGE1 was added to indomethacin-treated tissues, Isc and Rt were restored to control levels.(ABSTRACT TRUNCATED AT 250 WORDS)